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Date:   Thu, 19 Jan 2023 14:54:19 +0200
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Subject: Re: [PATCH v6 04/10] drm/hdcp: Expand HDCP helper library for
 enable/disable/check
Content-Language: en-GB
To:     Mark Yacoub <markyacoub@chromium.org>, quic_khsieh@quicinc.com,
        linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org,
        freedreno@lists.freedesktop.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org
Cc:     robdclark@gmail.com, quic_abhinavk@quicinc.com, sean@poorly.run,
        airlied@gmail.com, daniel@ffwll.ch, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, agross@kernel.org,
        andersson@kernel.org, konrad.dybcio@somainline.org,
        jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com,
        rodrigo.vivi@intel.com, tvrtko.ursulin@linux.intel.com,
        tzimmermann@suse.de, ville.syrjala@linux.intel.com,
        stanislav.lisovskiy@intel.com, matthew.d.roper@intel.com,
        imre.deak@intel.com, lucas.demarchi@intel.com,
        manasi.d.navare@intel.com, swati2.sharma@intel.com,
        bhanuprakash.modem@intel.com, javierm@redhat.com,
        jose.souza@intel.com, lyude@redhat.com, hbh25y@gmail.com,
        arun.r.murthy@intel.com, ashutosh.dixit@intel.com,
        ankit.k.nautiyal@intel.com, maxime@cerno.tech, swboyd@chromium.org,
        christophe.jaillet@wanadoo.fr, quic_sbillaka@quicinc.com,
        johan+linaro@kernel.org, dianders@chromium.org, marex@denx.de,
        quic_jesszhan@quicinc.com, bjorn.andersson@linaro.org,
        abhinavk@codeaurora.org, seanpaul@chromium.org,
        Jani Nikula <jani.nikula@intel.com>
References: <20230118193015.911074-1-markyacoub@google.com>
 <20230118193015.911074-5-markyacoub@google.com>
From:   Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
In-Reply-To: <20230118193015.911074-5-markyacoub@google.com>
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Precedence: bulk

On 18/01/2023 21:30, Mark Yacoub wrote:
> From: Sean Paul <seanpaul@chromium.org>
> 
> This patch expands upon the HDCP helper library to manage HDCP
> enable, disable, and check.
> 
> Previous to this patch, the majority of the state management and sink
> interaction is tucked inside the Intel driver with the understanding
> that once a new platform supported HDCP we could make good decisions
> about what should be centralized. With the addition of HDCP support
> for Qualcomm, it's time to migrate the protocol-specific bits of HDCP
> authentication, key exchange, and link checks to the HDCP helper.
> 
> In terms of functionality, this migration is 1:1 with the Intel driver,
> however things are laid out a bit differently than with intel_hdcp.c,
> which is why this is a separate patch from the i915 transition to the
> helper. On i915, the shim vtable is used to account for HDMI vs. DP
> vs. DP-MST differences whereas the helper library uses a LUT to
> account for the register offsets and a remote read function to route
> the messages. On i915, storing the sink information in the source is
> done inline whereas now we use the new drm_hdcp_helper_funcs vtable
> to store and fetch information to/from source hw. Finally, instead of
> calling enable/disable directly from the driver, we'll leave that
> decision to the helper and by calling drm_hdcp_helper_atomic_commit()
> from the driver. All told, this will centralize the protocol and state
> handling in the helper, ensuring we collect all of our bugs^Wlogic
> in one place.
> 
> Cc: Abhinav Kumar <abhinavk@codeaurora.org>
> Acked-by: Jani Nikula <jani.nikula@intel.com>
> Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
> Signed-off-by: Sean Paul <seanpaul@chromium.org>
> Signed-off-by: Mark Yacoub <markyacoub@chromium.org>
> Link: https://patchwork.freedesktop.org/patch/msgid/20210913175747.47456-5-sean@poorly.run #v1
> Link: https://patchwork.freedesktop.org/patch/msgid/20210915203834.1439-5-sean@poorly.run #v2
> Link: https://patchwork.freedesktop.org/patch/msgid/20211001151145.55916-5-sean@poorly.run #v3
> Link: https://patchwork.freedesktop.org/patch/msgid/20211105030434.2828845-5-sean@poorly.run #v4
> Link: https://patchwork.freedesktop.org/patch/msgid/20220411204741.1074308-5-sean@poorly.run #v5
> 
> Changes in v2:
> -Fixed set-but-unused variable identified by 0-day
> Changes in v3:
> -Fixed uninitialized variable warning identified by 0-day
> Changes in v4:
> -None
> Changes in v5:
> -None
> Changes in v6:
> -Fixed typo in function descriptions
> -Rebased: Moved the new code between drm_hdcp.h and drm_hdcp_helper.c/h
> -Add missing headers. Reported-by: kernel test robot <lkp@intel.com>
> 
> ---
>   drivers/gpu/drm/display/drm_hdcp_helper.c | 1109 +++++++++++++++++++++
>   include/drm/display/drm_hdcp.h            |  168 +++-
>   include/drm/display/drm_hdcp_helper.h     |   30 +-
>   3 files changed, 1305 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/display/drm_hdcp_helper.c b/drivers/gpu/drm/display/drm_hdcp_helper.c
> index ce92f1cac251..de8c006b9cda 100644
> --- a/drivers/gpu/drm/display/drm_hdcp_helper.c
> +++ b/drivers/gpu/drm/display/drm_hdcp_helper.c
> @@ -6,13 +6,18 @@
>    * Ramalingam C <ramalingam.c@intel.com>
>    */
>   
> +#include <linux/delay.h>
>   #include <linux/device.h>
>   #include <linux/err.h>
>   #include <linux/gfp.h>
> +#include <linux/i2c.h>
> +#include <linux/iopoll.h>
>   #include <linux/export.h>
>   #include <linux/slab.h>
>   #include <linux/firmware.h>
> +#include <linux/workqueue.h>
>   
> +#include <drm/display/drm_dp_helper.h>
>   #include <drm/display/drm_hdcp_helper.h>
>   #include <drm/drm_sysfs.h>
>   #include <drm/drm_print.h>
> @@ -512,3 +517,1107 @@ bool drm_hdcp_atomic_check(struct drm_connector *connector,
>   	return old_hdcp != new_hdcp;
>   }
>   EXPORT_SYMBOL(drm_hdcp_atomic_check);
> +
> +struct drm_hdcp_helper_data {
> +	struct mutex mutex;
> +	struct mutex *driver_mutex;
> +
> +	struct drm_connector *connector;
> +	const struct drm_hdcp_helper_funcs *funcs;
> +
> +	u64 value;
> +	unsigned int enabled_type;
> +
> +	struct delayed_work check_work;
> +	struct work_struct prop_work;
> +
> +	struct drm_dp_aux *aux;
> +	const struct drm_hdcp_hdcp1_receiver_reg_lut *hdcp1_lut;
> +};
> +
> +struct drm_hdcp_hdcp1_receiver_reg_lut {
> +	unsigned int bksv;
> +	unsigned int ri;
> +	unsigned int aksv;
> +	unsigned int an;
> +	unsigned int ainfo;
> +	unsigned int v[5];
> +	unsigned int bcaps;
> +	unsigned int bcaps_mask_repeater_present;
> +	unsigned int bstatus;
> +};
> +
> +static const struct drm_hdcp_hdcp1_receiver_reg_lut drm_hdcp_hdcp1_ddc_lut = {
> +	.bksv = DRM_HDCP_DDC_BKSV,
> +	.ri = DRM_HDCP_DDC_RI_PRIME,
> +	.aksv = DRM_HDCP_DDC_AKSV,
> +	.an = DRM_HDCP_DDC_AN,
> +	.ainfo = DRM_HDCP_DDC_AINFO,
> +	.v = { DRM_HDCP_DDC_V_PRIME(0), DRM_HDCP_DDC_V_PRIME(1),
> +	       DRM_HDCP_DDC_V_PRIME(2), DRM_HDCP_DDC_V_PRIME(3),
> +	       DRM_HDCP_DDC_V_PRIME(4) },
> +	.bcaps = DRM_HDCP_DDC_BCAPS,
> +	.bcaps_mask_repeater_present = DRM_HDCP_DDC_BCAPS_REPEATER_PRESENT,
> +	.bstatus = DRM_HDCP_DDC_BSTATUS,
> +};
> +
> +static const struct drm_hdcp_hdcp1_receiver_reg_lut drm_hdcp_hdcp1_dpcd_lut = {
> +	.bksv = DP_AUX_HDCP_BKSV,
> +	.ri = DP_AUX_HDCP_RI_PRIME,
> +	.aksv = DP_AUX_HDCP_AKSV,
> +	.an = DP_AUX_HDCP_AN,
> +	.ainfo = DP_AUX_HDCP_AINFO,
> +	.v = { DP_AUX_HDCP_V_PRIME(0), DP_AUX_HDCP_V_PRIME(1),
> +	       DP_AUX_HDCP_V_PRIME(2), DP_AUX_HDCP_V_PRIME(3),
> +	       DP_AUX_HDCP_V_PRIME(4) },
> +	.bcaps = DP_AUX_HDCP_BCAPS,
> +	.bcaps_mask_repeater_present = DP_BCAPS_REPEATER_PRESENT,
> +
> +	/*
> +	 * For some reason the HDMI and DP HDCP specs call this register
> +	 * definition by different names. In the HDMI spec, it's called BSTATUS,
> +	 * but in DP it's called BINFO.
> +	 */
> +	.bstatus = DP_AUX_HDCP_BINFO,
> +};
> +
> +static int drm_hdcp_remote_ddc_read(struct i2c_adapter *i2c,
> +				    unsigned int offset, u8 *value, size_t len)
> +{
> +	int ret;
> +	u8 start = offset & 0xff;
> +	struct i2c_msg msgs[] = { {
> +					  .addr = DRM_HDCP_DDC_ADDR,
> +					  .flags = 0,
> +					  .len = 1,
> +					  .buf = &start,
> +				  },
> +				  { .addr = DRM_HDCP_DDC_ADDR,
> +				    .flags = I2C_M_RD,
> +				    .len = len,
> +				    .buf = value } };

Very strange indentation, I'd say.

> +	ret = i2c_transfer(i2c, msgs, ARRAY_SIZE(msgs));
> +	if (ret == ARRAY_SIZE(msgs))
> +		return 0;
> +	return ret >= 0 ? -EIO : ret;
> +}
> +
> +static int drm_hdcp_remote_dpcd_read(struct drm_dp_aux *aux,
> +				     unsigned int offset, u8 *value, size_t len)
> +{
> +	ssize_t ret;
> +
> +	ret = drm_dp_dpcd_read(aux, offset, value, len);
> +	if (ret != len) {
> +		if (ret >= 0)
> +			return -EIO;
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int drm_hdcp_remote_read(struct drm_hdcp_helper_data *data,
> +				unsigned int offset, u8 *value, u8 len)
> +{
> +	if (data->aux)
> +		return drm_hdcp_remote_dpcd_read(data->aux, offset, value, len);
> +	else
> +		return drm_hdcp_remote_ddc_read(data->connector->ddc, offset,
> +						value, len);
> +}
> +
> +static int drm_hdcp_remote_ddc_write(struct i2c_adapter *i2c,
> +				     unsigned int offset, u8 *buffer,
> +				     size_t size)
> +{
> +	int ret;
> +	u8 *write_buf;
> +	struct i2c_msg msg;
> +
> +	write_buf = kzalloc(size + 1, GFP_KERNEL);
> +	if (!write_buf)
> +		return -ENOMEM;
> +
> +	write_buf[0] = offset & 0xff;
> +	memcpy(&write_buf[1], buffer, size);
> +
> +	msg.addr = DRM_HDCP_DDC_ADDR;
> +	msg.flags = 0, msg.len = size + 1, msg.buf = write_buf;
> +
> +	ret = i2c_transfer(i2c, &msg, 1);
> +	if (ret == 1)
> +		ret = 0;
> +	else if (ret >= 0)
> +		ret = -EIO;
> +
> +	kfree(write_buf);
> +	return ret;
> +}
> +
> +static int drm_hdcp_remote_dpcd_write(struct drm_dp_aux *aux,
> +				      unsigned int offset, u8 *value,
> +				      size_t len)
> +{
> +	ssize_t ret;
> +
> +	ret = drm_dp_dpcd_write(aux, offset, value, len);
> +	if (ret != len) {
> +		if (ret >= 0)
> +			return -EIO;
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int drm_hdcp_remote_write(struct drm_hdcp_helper_data *data,
> +				 unsigned int offset, u8 *value, u8 len)
> +{
> +	if (data->aux)
> +		return drm_hdcp_remote_dpcd_write(data->aux, offset, value,
> +						  len);
> +	else
> +		return drm_hdcp_remote_ddc_write(data->connector->ddc, offset,
> +						 value, len);
> +}
> +
> +static bool drm_hdcp_is_ksv_valid(struct drm_hdcp_ksv *ksv)
> +{
> +	/* Valid Ksv has 20 0's and 20 1's */
> +	return hweight32(ksv->words[0]) + hweight32(ksv->words[1]) == 20;
> +}
> +
> +static int drm_hdcp_read_valid_bksv(struct drm_hdcp_helper_data *data,
> +				    struct drm_hdcp_ksv *bksv)
> +{
> +	int ret, i, tries = 2;
> +
> +	/* HDCP spec states that we must retry the bksv if it is invalid */
> +	for (i = 0; i < tries; i++) {
> +		ret = drm_hdcp_remote_read(data, data->hdcp1_lut->bksv,
> +					   bksv->bytes, DRM_HDCP_KSV_LEN);
> +		if (ret)
> +			return ret;
> +
> +		if (drm_hdcp_is_ksv_valid(bksv))
> +			break;
> +	}
> +	if (i == tries) {
> +		drm_dbg_kms(data->connector->dev, "Bksv is invalid %*ph\n",
> +			    DRM_HDCP_KSV_LEN, bksv->bytes);
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * drm_hdcp_helper_hdcp1_capable - Checks if the sink is capable of HDCP 1.x.
> + *
> + * @data: pointer to the HDCP helper data.
> + * @capable: pointer to a bool which will contain true if the sink is capable.
> + *
> + * Returns:
> + * -errno if the transacation between source and sink fails.
> + */
> +int drm_hdcp_helper_hdcp1_capable(struct drm_hdcp_helper_data *data,
> +				  bool *capable)
> +{
> +	/*
> +	 * DisplayPort has a dedicated bit for this in DPCD whereas HDMI spec
> +	 * states that transmitters should use bksv to determine capability.
> +	 */
> +	if (data->aux) {
> +		int ret;
> +		u8 bcaps;
> +
> +		ret = drm_hdcp_remote_read(data, data->hdcp1_lut->bcaps, &bcaps,
> +					   1);
> +		*capable = !ret && (bcaps & DP_BCAPS_HDCP_CAPABLE);
> +	} else {
> +		struct drm_hdcp_ksv bksv;
> +
> +		*capable = drm_hdcp_read_valid_bksv(data, &bksv) == 0;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(drm_hdcp_helper_hdcp1_capable);

I'd say that all previous code begs to add corresponding callbacks to 
the hdcp_helper_data and then just call them instead of manually 
multiplexing the code basing on data->aux.

> +
> +static void drm_hdcp_update_value(struct drm_hdcp_helper_data *data, u64 value,
> +				  bool update_property)
> +{
> +	WARN_ON(!mutex_is_locked(&data->mutex));
> +
> +	data->value = value;
> +	if (update_property) {
> +		drm_connector_get(data->connector);
> +		schedule_work(&data->prop_work);
> +	}
> +}
> +
> +static int
> +drm_hdcp_helper_hdcp1_ksv_fifo_ready(struct drm_hdcp_helper_data *data)
> +{
> +	int ret;
> +	u8 val, mask;
> +
> +	/* KSV FIFO ready bit is stored in different locations on DP v. HDMI */
> +	if (data->aux) {
> +		ret = drm_hdcp_remote_dpcd_read(data->aux, DP_AUX_HDCP_BSTATUS,
> +						&val, 1);
> +		mask = DP_BSTATUS_READY;
> +	} else {
> +		ret = drm_hdcp_remote_ddc_read(data->connector->ddc,
> +					       DRM_HDCP_DDC_BCAPS, &val, 1);
> +		mask = DRM_HDCP_DDC_BCAPS_KSV_FIFO_READY;
> +	}
> +	if (ret)
> +		return ret;
> +	if (val & mask)
> +		return 0;
> +
> +	return -EAGAIN;
> +}

Again, this can go to hdcp-kind ops.

> +
> +static int
> +drm_hdcp_helper_hdcp1_read_ksv_fifo(struct drm_hdcp_helper_data *data, u8 *fifo,
> +				    u8 num_downstream)
> +{
> +	struct drm_device *dev = data->connector->dev;
> +	int ret, i;
> +
> +	/* Over HDMI, read the whole thing at once */
> +	if (data->connector->ddc) {

And here for some reason one choose data->connector->ddc instead of 
data->aux, so grepping for data->aux would not return this function.

> +		ret = drm_hdcp_remote_ddc_read(
> +			data->connector->ddc, DRM_HDCP_DDC_KSV_FIFO, fifo,
> +			num_downstream * DRM_HDCP_KSV_LEN);
> +		if (ret)
> +			drm_err(dev, "DDC ksv fifo read failed (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	/* Over DP, read via 15 byte window (3 entries @ 5 bytes each) */
> +	for (i = 0; i < num_downstream; i += 3) {
> +		size_t len = min(num_downstream - i, 3) * DRM_HDCP_KSV_LEN;
> +		ret = drm_hdcp_remote_dpcd_read(data->aux, DP_AUX_HDCP_KSV_FIFO,
> +						fifo + i * DRM_HDCP_KSV_LEN,
> +						len);
> +		if (ret) {
> +			drm_err(dev, "Read ksv[%d] from DP/AUX failed (%d)\n",
> +				i, ret);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int drm_hdcp_helper_hdcp1_read_v_prime(struct drm_hdcp_helper_data *data,
> +					      u32 *v_prime)
> +{
> +	struct drm_device *dev = data->connector->dev;
> +	int ret, i;
> +
> +	for (i = 0; i < DRM_HDCP_V_PRIME_NUM_PARTS; i++) {
> +		ret = drm_hdcp_remote_read(data, data->hdcp1_lut->v[i],
> +					   (u8 *)&v_prime[i],
> +					   DRM_HDCP_V_PRIME_PART_LEN);
> +		if (ret) {
> +			drm_dbg_kms(dev, "Read v'[%d] from failed (%d)\n", i,
> +				    ret);
> +			return ret >= 0 ? -EIO : ret;
> +		}
> +	}
> +	return 0;
> +}
> +
> +static int
> +drm_hdcp_helper_hdcp1_authenticate_downstream(struct drm_hdcp_helper_data *data)
> +{
> +	struct drm_connector *connector = data->connector;
> +	struct drm_device *dev = connector->dev;
> +	u32 v_prime[DRM_HDCP_V_PRIME_NUM_PARTS];
> +	u8 bstatus[DRM_HDCP_BSTATUS_LEN];
> +	u8 num_downstream, *ksv_fifo;
> +	int ret, i, tries = 3;
> +
> +	ret = read_poll_timeout(drm_hdcp_helper_hdcp1_ksv_fifo_ready, ret, !ret,
> +				10 * 1000, 5 * 1000 * 1000, false, data);
> +	if (ret) {
> +		drm_err(dev, "Failed to poll ksv ready, %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = drm_hdcp_remote_read(data, data->hdcp1_lut->bstatus, bstatus,
> +				   DRM_HDCP_BSTATUS_LEN);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * When repeater reports 0 device count, HDCP1.4 spec allows disabling
> +	 * the HDCP encryption. That implies that repeater can't have its own
> +	 * display. As there is no consumption of encrypted content in the
> +	 * repeater with 0 downstream devices, we are failing the
> +	 * authentication.
> +	 */
> +	num_downstream = DRM_HDCP_NUM_DOWNSTREAM(bstatus[0]);
> +	if (num_downstream == 0) {
> +		drm_err(dev, "Repeater with zero downstream devices, %*ph\n",
> +			DRM_HDCP_BSTATUS_LEN, bstatus);
> +		return -EINVAL;
> +	}
> +
> +	ksv_fifo = kcalloc(DRM_HDCP_KSV_LEN, num_downstream, GFP_KERNEL);
> +	if (!ksv_fifo)
> +		return -ENOMEM;
> +
> +	ret = drm_hdcp_helper_hdcp1_read_ksv_fifo(data, ksv_fifo,
> +						  num_downstream);

I'd have moved kcalloc into read_ksv_fifo.

> +	if (ret) {
> +		drm_err(dev, "Failed to read ksv fifo, %d/%d\n", num_downstream,
> +			ret);
> +		goto out;
> +	}
> +
> +	if (drm_hdcp_check_ksvs_revoked(dev, ksv_fifo, num_downstream)) {
> +		drm_err(dev, "Revoked Ksv(s) in ksv_fifo\n");
> +		ret = -EPERM;
> +		goto out;
> +	}
> +
> +	/*
> +	 * When V prime mismatches, DP Spec mandates re-read of
> +	 * V prime at least twice.
> +	 */
> +	for (i = 0; i < tries; i++) {
> +		ret = drm_hdcp_helper_hdcp1_read_v_prime(data, v_prime);
> +		if (ret)
> +			continue;
> +
> +		ret = data->funcs->hdcp1_store_ksv_fifo(
> +			connector, ksv_fifo, num_downstream, bstatus, v_prime);
> +		if (!ret)
> +			break;
> +	}
> +	if (ret)
> +		drm_err(dev, "Could not validate KSV FIFO with V' %d\n", ret);
> +
> +out:
> +	if (!ret)
> +		drm_dbg_kms(dev, "HDCP is enabled (%d downstream devices)\n",
> +			    num_downstream);
> +
> +	kfree(ksv_fifo);
> +	return ret;
> +}
> +
> +static int drm_hdcp_helper_hdcp1_validate_ri(struct drm_hdcp_helper_data *data)
> +{
> +	union {
> +		u32 word;
> +		u8 bytes[DRM_HDCP_RI_LEN];
> +	} ri_prime = { .word = 0 };
> +	struct drm_connector *connector = data->connector;
> +	struct drm_device *dev = connector->dev;
> +	int ret;
> +
> +	ret = drm_hdcp_remote_read(data, data->hdcp1_lut->ri, ri_prime.bytes,
> +				   DRM_HDCP_RI_LEN);
> +	if (ret) {
> +		drm_err(dev, "Failed to read R0' %d\n", ret);
> +		return ret;
> +	}
> +
> +	return data->funcs->hdcp1_match_ri(connector, ri_prime.word);
> +}
> +
> +static int drm_hdcp_helper_hdcp1_authenticate(struct drm_hdcp_helper_data *data)
> +{
> +	union {
> +		u32 word;
> +		u8 bytes[DRM_HDCP_BSTATUS_LEN];
> +	} bstatus;
> +	const struct drm_hdcp_helper_funcs *funcs = data->funcs;
> +	struct drm_connector *connector = data->connector;
> +	struct drm_device *dev = connector->dev;
> +	unsigned long r0_prime_timeout, r0_prime_remaining_us = 0, tmp_jiffies;
> +	struct drm_hdcp_ksv aksv;
> +	struct drm_hdcp_ksv bksv;
> +	struct drm_hdcp_an an;
> +	bool repeater_present;
> +	int ret, i, tries = 3;
> +	u8 bcaps;
> +
> +	if (funcs->hdcp1_read_an_aksv) {
> +		ret = funcs->hdcp1_read_an_aksv(connector, an.words,
> +						aksv.words);
> +		if (ret) {
> +			drm_err(dev, "Failed to read An/Aksv values, %d\n",
> +				ret);
> +			return ret;
> +		}
> +
> +		ret = drm_hdcp_remote_write(data, data->hdcp1_lut->an, an.bytes,
> +					    DRM_HDCP_AN_LEN);
> +		if (ret) {
> +			drm_err(dev, "Failed to write An to receiver, %d\n",
> +				ret);
> +			return ret;
> +		}
> +
> +		ret = drm_hdcp_remote_write(data, data->hdcp1_lut->aksv,
> +					    aksv.bytes, DRM_HDCP_KSV_LEN);
> +		if (ret) {
> +			drm_err(dev, "Failed to write Aksv to receiver, %d\n",
> +				ret);
> +			return ret;
> +		}
> +	} else {
> +		ret = funcs->hdcp1_send_an_aksv(connector);
> +		if (ret) {
> +			drm_err(dev, "Failed to read An/Aksv values, %d\n",
> +				ret);
> +			return ret;
> +		}
> +	}
> +
> +	/*
> +	 * Timeout for R0' to become available. The spec says 100ms from Aksv,
> +	 * but some monitors can take longer than this. We'll set the timeout at
> +	 * 300ms just to be sure.
> +	 */
> +	r0_prime_timeout = jiffies + msecs_to_jiffies(300);
> +
> +	memset(&bksv, 0, sizeof(bksv));
> +
> +	ret = drm_hdcp_read_valid_bksv(data, &bksv);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (drm_hdcp_check_ksvs_revoked(dev, bksv.bytes, 1)) {
> +		drm_err(dev, "BKSV is revoked\n");
> +		return -EPERM;
> +	}
> +
> +	ret = drm_hdcp_remote_read(data, data->hdcp1_lut->bcaps, &bcaps, 1);
> +	if (ret)
> +		return ret;
> +
> +	memset(&bstatus, 0, sizeof(bstatus));
> +
> +	ret = drm_hdcp_remote_read(data, data->hdcp1_lut->bstatus,
> +				   bstatus.bytes, DRM_HDCP_BSTATUS_LEN);
> +	if (ret)
> +		return ret;
> +
> +	if (DRM_HDCP_MAX_DEVICE_EXCEEDED(bstatus.bytes[0]) ||
> +	    DRM_HDCP_MAX_CASCADE_EXCEEDED(bstatus.bytes[1])) {
> +		drm_err(dev, "Max Topology Limit Exceeded, bstatus=%*ph\n",
> +			DRM_HDCP_BSTATUS_LEN, bstatus.bytes);
> +		return -EPERM;
> +	}
> +
> +	repeater_present = bcaps & data->hdcp1_lut->bcaps_mask_repeater_present;
> +
> +	ret = funcs->hdcp1_store_receiver_info(
> +		connector, bksv.words, bstatus.word, bcaps, repeater_present);
> +	if (ret) {
> +		drm_err(dev, "Failed to store bksv, %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = funcs->hdcp1_enable_encryption(connector);
> +	if (ret)
> +		return ret;
> +
> +	ret = funcs->hdcp1_wait_for_r0(connector);
> +	if (ret)
> +		return ret;
> +
> +	tmp_jiffies = jiffies;
> +	if (time_before(tmp_jiffies, r0_prime_timeout))
> +		r0_prime_remaining_us =
> +			jiffies_to_usecs(r0_prime_timeout - tmp_jiffies);
> +
> +	/*
> +	 * Wait for R0' to become available.
> +	 *
> +	 * On DP, there's an R0_READY bit available but no such bit
> +	 * exists on HDMI. So poll the ready bit for DP and just wait the
> +	 * remainder of the 300 ms timeout for HDMI.
> +	 */
> +	if (data->aux) {
> +		u8 val;
> +		ret = read_poll_timeout(
> +			drm_hdcp_remote_dpcd_read, ret,
> +			!ret && (val & DP_BSTATUS_R0_PRIME_READY), 1000,
> +			r0_prime_remaining_us, false, data->aux,
> +			DP_AUX_HDCP_BSTATUS, &val, 1);
> +		if (ret) {
> +			drm_err(dev, "R0' did not become ready %d\n", ret);
> +			return ret;
> +		}
> +	} else {
> +		usleep_range(r0_prime_remaining_us,
> +			     r0_prime_remaining_us + 1000);
> +	}

Another hdcp backend function.

> +
> +	/*
> +	 * DP HDCP Spec mandates the two more reattempt to read R0, in case
> +	 * of R0 mismatch.
> +	 */
> +	for (i = 0; i < tries; i++) {
> +		ret = drm_hdcp_helper_hdcp1_validate_ri(data);
> +		if (!ret)
> +			break;
> +	}
> +	if (ret) {
> +		drm_err(dev, "Failed to match R0/R0', aborting HDCP %d\n", ret);
> +		return ret;
> +	}
> +
> +	if (repeater_present)
> +		return drm_hdcp_helper_hdcp1_authenticate_downstream(data);
> +
> +	drm_dbg_kms(dev, "HDCP is enabled (no repeater present)\n");
> +	return 0;
> +}
> +
> +static int drm_hdcp_helper_hdcp1_enable(struct drm_hdcp_helper_data *data)
> +{
> +	struct drm_connector *connector = data->connector;
> +	struct drm_device *dev = connector->dev;
> +	int i, ret, tries = 3;
> +
> +	drm_dbg_kms(dev, "[%s:%d] HDCP is being enabled...\n", connector->name,
> +		    connector->base.id);
> +
> +	/* In case of authentication failures, HDCP spec expects reauth. */
> +	for (i = 0; i < tries; i++) {
> +		ret = drm_hdcp_helper_hdcp1_authenticate(data);
> +		if (!ret)
> +			return 0;
> +
> +		drm_dbg_kms(dev, "HDCP Auth failure (%d)\n", ret);
> +
> +		/* Ensuring HDCP encryption and signalling are stopped. */
> +		data->funcs->hdcp1_disable(data->connector);
> +	}
> +
> +	drm_err(dev, "HDCP authentication failed (%d tries/%d)\n", tries, ret);
> +	return ret;
> +}
> +
> +static inline void
> +drm_hdcp_helper_driver_lock(struct drm_hdcp_helper_data *data)
> +{
> +	if (data->driver_mutex)
> +		mutex_lock(data->driver_mutex);
> +}
> +
> +static inline void
> +drm_hdcp_helper_driver_unlock(struct drm_hdcp_helper_data *data)
> +{
> +	if (data->driver_mutex)
> +		mutex_unlock(data->driver_mutex);
> +}
> +
> +static int drm_hdcp_helper_enable_hdcp(struct drm_hdcp_helper_data *data,
> +				       struct drm_atomic_state *state,
> +				       struct mutex *driver_mutex)
> +{
> +	struct drm_connector *connector = data->connector;
> +	struct drm_connector_state *conn_state;
> +	struct drm_device *dev = connector->dev;
> +	unsigned long check_link_interval = DRM_HDCP2_CHECK_PERIOD_MS;
> +	bool capable;
> +	int ret = 0;
> +
> +	conn_state = drm_atomic_get_new_connector_state(state, connector);
> +
> +	mutex_lock(&data->mutex);
> +
> +	if (data->value == DRM_MODE_CONTENT_PROTECTION_ENABLED) {
> +		drm_hdcp_update_value(data, DRM_MODE_CONTENT_PROTECTION_ENABLED,
> +				      true);
> +		goto out_data_mutex;
> +	}
> +
> +	drm_WARN_ON(dev, data->driver_mutex != NULL);
> +	data->driver_mutex = driver_mutex;
> +
> +	drm_hdcp_helper_driver_lock(data);
> +
> +	if (data->funcs->setup) {
> +		ret = data->funcs->setup(connector, state);
> +		if (ret) {
> +			drm_err(dev, "Failed to setup HDCP %d\n", ret);
> +			goto out;
> +		}
> +	}
> +
> +	if (!data->funcs->are_keys_valid ||
> +	    !data->funcs->are_keys_valid(connector)) {
> +		if (data->funcs->load_keys) {
> +			ret = data->funcs->load_keys(connector);
> +			if (ret) {
> +				drm_err(dev, "Failed to load HDCP keys %d\n",
> +					ret);
> +				goto out;
> +			}
> +		}
> +	}
> +
> +	/*
> +	 * Considering that HDCP2.2 is more secure than HDCP1.4, If the setup
> +	 * is capable of HDCP2.2, it is preferred to use HDCP2.2.
> +	 */
> +	ret = data->funcs->hdcp2_capable(connector, &capable);
> +	if (ret) {
> +		drm_err(dev, "HDCP 2.x capability check failed %d\n", ret);
> +		goto out;
> +	}
> +	if (capable) {
> +		data->enabled_type = DRM_MODE_HDCP_CONTENT_TYPE1;
> +		ret = data->funcs->hdcp2_enable(connector);
> +		if (!ret) {
> +			check_link_interval = DRM_HDCP2_CHECK_PERIOD_MS;
> +			goto out;
> +		}
> +	}
> +
> +	/*
> +	 * When HDCP2.2 fails and Content Type is not Type1, HDCP1.4 will
> +	 * be attempted.
> +	 */
> +	ret = drm_hdcp_helper_hdcp1_capable(data, &capable);
> +	if (ret) {
> +		drm_err(dev, "HDCP 1.x capability check failed %d\n", ret);
> +		goto out;
> +	}
> +	if (capable &&
> +	    conn_state->content_type != DRM_MODE_HDCP_CONTENT_TYPE1) {
> +		data->enabled_type = DRM_MODE_HDCP_CONTENT_TYPE0;
> +		ret = drm_hdcp_helper_hdcp1_enable(data);
> +		if (!ret)
> +			check_link_interval = DRM_HDCP_CHECK_PERIOD_MS;
> +	}
> +
> +out:
> +	if (!ret) {
> +		schedule_delayed_work(&data->check_work, check_link_interval);
> +		drm_hdcp_update_value(data, DRM_MODE_CONTENT_PROTECTION_ENABLED,
> +				      true);
> +	}
> +
> +	drm_hdcp_helper_driver_unlock(data);
> +	if (ret)
> +		data->driver_mutex = NULL;
> +
> +out_data_mutex:
> +	mutex_unlock(&data->mutex);
> +	return ret;
> +}
> +
> +static int drm_hdcp_helper_disable_hdcp(struct drm_hdcp_helper_data *data)
> +{
> +	int ret = 0;
> +
> +	mutex_lock(&data->mutex);
> +	drm_hdcp_helper_driver_lock(data);
> +
> +	if (data->value == DRM_MODE_CONTENT_PROTECTION_UNDESIRED)
> +		goto out;
> +
> +	drm_dbg_kms(data->connector->dev, "[%s:%d] HDCP is being disabled...\n",
> +		    data->connector->name, data->connector->base.id);
> +
> +	drm_hdcp_update_value(data, DRM_MODE_CONTENT_PROTECTION_UNDESIRED,
> +			      true);
> +
> +	if (data->enabled_type == DRM_MODE_HDCP_CONTENT_TYPE1)
> +		ret = data->funcs->hdcp2_disable(data->connector);
> +	else
> +		ret = data->funcs->hdcp1_disable(data->connector);
> +
> +	drm_dbg_kms(data->connector->dev, "HDCP is disabled\n");
> +
> +out:
> +	drm_hdcp_helper_driver_unlock(data);
> +	data->driver_mutex = NULL;
> +	mutex_unlock(&data->mutex);
> +	cancel_delayed_work_sync(&data->check_work);
> +	return ret;
> +}
> +
> +/**
> + * drm_hdcp_helper_atomic_commit - Helper for drivers to call during commit to
> + * enable/disable HDCP
> + *
> + * @data: pointer to the @drm_hdcp_helper_data for the connector
> + * @state: pointer to the atomic state being committed
> + * @driver_mutex: driver-provided lock to be used while interacting with the driver
> + *
> + * This function can be used by display drivers to determine when HDCP should be
> + * enabled or disabled based on the connector state. It should be called during
> + * steady-state commits as well as connector enable/disable. The function will
> + * handle the HDCP authentication/encryption logic, calling back into the driver
> + * when source operations are necessary.
> + *
> + * @driver_mutex will be retained and used for the duration of the HDCP session
> + * since it will be needed for link checks and retries. This mutex is useful if
> + * the driver has shared resources across connectors which must be serialized.
> + * For example, driver_mutex can be used for MST connectors sharing a common
> + * encoder which should not be accessed/changed concurrently. When the
> + * connector's session is torn down, the mutex will be forgotten by the helper
> + * for this connector until the next session.
> + */
> +void drm_hdcp_helper_atomic_commit(struct drm_hdcp_helper_data *data,
> +				   struct drm_atomic_state *state,
> +				   struct mutex *driver_mutex)
> +{
> +	struct drm_connector *connector = data->connector;
> +	struct drm_connector_state *conn_state;
> +	bool type_changed;
> +
> +	conn_state = drm_atomic_get_new_connector_state(state, connector);
> +
> +	type_changed = conn_state->hdcp_content_type != data->enabled_type;
> +
> +	if (conn_state->content_protection ==
> +	    DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
> +		drm_hdcp_helper_disable_hdcp(data);
> +		return;
> +	}
> +
> +	if (!conn_state->crtc) {
> +		drm_hdcp_helper_disable_hdcp(data);
> +
> +		/* Restore property to DESIRED so it's retried later */
> +		if (conn_state->content_protection ==
> +		    DRM_MODE_CONTENT_PROTECTION_ENABLED) {
> +			mutex_lock(&data->mutex);
> +			drm_hdcp_update_value(
> +				data, DRM_MODE_CONTENT_PROTECTION_DESIRED,
> +				true);
> +			mutex_unlock(&data->mutex);
> +		}
> +		return;
> +	}
> +
> +	/* Already enabled */
> +	if (conn_state->content_protection ==
> +	    DRM_MODE_CONTENT_PROTECTION_ENABLED)
> +		return;
> +
> +	/* Disable and re-enable HDCP on content type change */
> +	if (type_changed)
> +		drm_hdcp_helper_disable_hdcp(data);
> +
> +	drm_hdcp_helper_enable_hdcp(data, state, driver_mutex);
> +}
> +EXPORT_SYMBOL(drm_hdcp_helper_atomic_commit);
> +
> +static void drm_hdcp_helper_prop_work(struct work_struct *work)
> +{
> +	struct drm_hdcp_helper_data *data =
> +		container_of(work, struct drm_hdcp_helper_data, prop_work);
> +	struct drm_connector *connector = data->connector;
> +	struct drm_device *dev = connector->dev;
> +
> +	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> +	mutex_lock(&data->mutex);
> +
> +	/*
> +	 * This worker is only used to flip between ENABLED/DESIRED. Either of
> +	 * those to UNDESIRED is handled by core. If value == UNDESIRED,
> +	 * we're running just after hdcp has been disabled, so just exit
> +	 */
> +	if (data->value != DRM_MODE_CONTENT_PROTECTION_UNDESIRED)
> +		drm_hdcp_update_content_protection(connector, data->value);
> +
> +	mutex_unlock(&data->mutex);
> +	drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +}
> +
> +static int drm_hdcp_hdcp1_check_link(struct drm_hdcp_helper_data *data)
> +{
> +	struct drm_connector *connector = data->connector;
> +	struct drm_device *dev = connector->dev;
> +	int ret;
> +
> +	if (data->funcs->hdcp1_check_link) {
> +		ret = data->funcs->hdcp1_check_link(connector);
> +		if (ret)
> +			goto retry;
> +	}
> +
> +	/* The link is checked differently for DP and HDMI */
> +	if (data->aux) {
> +		u8 bstatus;
> +		ret = drm_hdcp_remote_dpcd_read(data->aux, DP_AUX_HDCP_BSTATUS,
> +						&bstatus, 1);
> +		if (ret) {
> +			drm_err(dev, "Failed to read dpcd bstatus, %d\n", ret);
> +			return ret;
> +		}
> +		if (bstatus & (DP_BSTATUS_LINK_FAILURE | DP_BSTATUS_REAUTH_REQ))
> +			ret = -EINVAL;
> +	} else {
> +		ret = drm_hdcp_helper_hdcp1_validate_ri(data);
> +		if (ret)
> +			drm_err(dev, "Ri' mismatch, check failed (%d)\n", ret);
> +	}
> +	if (!ret)
> +		return 0;
> +
> +retry:
> +	drm_err(dev, "[%s:%d] HDCP link failed, retrying authentication\n",
> +		connector->name, connector->base.id);
> +
> +	ret = data->funcs->hdcp1_disable(connector);
> +	if (ret) {
> +		drm_err(dev, "Failed to disable hdcp (%d)\n", ret);
> +		drm_hdcp_update_value(data, DRM_MODE_CONTENT_PROTECTION_DESIRED,
> +				      true);
> +		return ret;
> +	}
> +
> +	ret = drm_hdcp_helper_hdcp1_enable(data);
> +	if (ret) {
> +		drm_err(dev, "Failed to enable hdcp (%d)\n", ret);
> +		drm_hdcp_update_value(data, DRM_MODE_CONTENT_PROTECTION_DESIRED,
> +				      true);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int drm_hdcp_hdcp2_check_link(struct drm_hdcp_helper_data *data)
> +{
> +	struct drm_connector *connector = data->connector;
> +	struct drm_device *dev = connector->dev;
> +	int ret;
> +
> +	ret = data->funcs->hdcp2_check_link(connector);
> +	if (!ret)
> +		return 0;
> +
> +	drm_err(dev, "[%s:%d] HDCP2 link failed, retrying authentication\n",
> +		connector->name, connector->base.id);
> +
> +	ret = data->funcs->hdcp2_disable(connector);
> +	if (ret) {
> +		drm_err(dev, "Failed to disable hdcp2 (%d)\n", ret);
> +		drm_hdcp_update_value(data, DRM_MODE_CONTENT_PROTECTION_DESIRED,
> +				      true);
> +		return ret;
> +	}
> +
> +	ret = data->funcs->hdcp2_enable(connector);
> +	if (ret) {
> +		drm_err(dev, "Failed to enable hdcp2 (%d)\n", ret);
> +		drm_hdcp_update_value(data, DRM_MODE_CONTENT_PROTECTION_DESIRED,
> +				      true);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void drm_hdcp_helper_check_work(struct work_struct *work)
> +{
> +	struct drm_hdcp_helper_data *data = container_of(
> +		to_delayed_work(work), struct drm_hdcp_helper_data, check_work);
> +	unsigned long check_link_interval;
> +
> +	mutex_lock(&data->mutex);
> +	if (data->value != DRM_MODE_CONTENT_PROTECTION_ENABLED)
> +		goto out_data_mutex;
> +
> +	drm_hdcp_helper_driver_lock(data);
> +
> +	if (data->enabled_type == DRM_MODE_HDCP_CONTENT_TYPE1) {
> +		if (drm_hdcp_hdcp2_check_link(data))
> +			goto out;
> +		check_link_interval = DRM_HDCP2_CHECK_PERIOD_MS;
> +	} else {
> +		if (drm_hdcp_hdcp1_check_link(data))
> +			goto out;
> +		check_link_interval = DRM_HDCP_CHECK_PERIOD_MS;
> +	}
> +	schedule_delayed_work(&data->check_work, check_link_interval);
> +
> +out:
> +	drm_hdcp_helper_driver_unlock(data);
> +out_data_mutex:
> +	mutex_unlock(&data->mutex);
> +}
> +
> +/**
> + * drm_hdcp_helper_schedule_hdcp_check - Schedule a check link cycle.
> + *
> + * @data: Pointer to the HDCP helper data.
> + *
> + * This function will kick off a check link cycle on behalf of the caller. This
> + * can be used by DP short hpd interrupt handlers, where the driver must poke
> + * the helper to check the link is still valid.
> + */
> +void drm_hdcp_helper_schedule_hdcp_check(struct drm_hdcp_helper_data *data)
> +{
> +	schedule_delayed_work(&data->check_work, 0);
> +}
> +EXPORT_SYMBOL(drm_hdcp_helper_schedule_hdcp_check);
> +
> +static struct drm_hdcp_helper_data *
> +drm_hdcp_helper_initialize(struct drm_connector *connector,
> +			   const struct drm_hdcp_helper_funcs *funcs,
> +			   bool attach_content_type_property)

The argument is misnamed. The called function 
drm_connector_attach_content_protection_property() uses different name, 
better use it instead. Also why would anyone (drm/msm?) not want the 
Conent Type propery?

> +{
> +	struct drm_hdcp_helper_data *out;
> +	int ret;
> +
> +	out = kzalloc(sizeof(*out), GFP_KERNEL);
> +	if (!out)
> +		return ERR_PTR(-ENOMEM);
> +
> +	out->connector = connector;
> +	out->funcs = funcs;
> +
> +	mutex_init(&out->mutex);
> +	out->value = DRM_MODE_CONTENT_PROTECTION_UNDESIRED;
> +
> +	INIT_DELAYED_WORK(&out->check_work, drm_hdcp_helper_check_work);
> +	INIT_WORK(&out->prop_work, drm_hdcp_helper_prop_work);
> +
> +	ret = drm_connector_attach_content_protection_property(
> +		connector, attach_content_type_property);
> +	if (ret) {
> +		drm_hdcp_helper_destroy(out);
> +		return ERR_PTR(ret);
> +	}
> +
> +	return out;
> +}
> +
> +/**
> + * drm_hdcp_helper_initialize_dp - Initializes the HDCP helpers for a
> + * DisplayPort connector
> + *
> + * @connector: pointer to the DisplayPort connector.
> + * @funcs: pointer to the vtable of HDCP helper funcs for this connector.
> + * @attach_content_type_property: True if the content_type property should be
> + * attached.
> + *
> + * This function initializes the HDCP helper for the given DisplayPort connector.
> + * This involves creating the Content Protection property as well as the Content
> + * Type property (if desired). Upon success, it will return a pointer to the
> + * HDCP helper data. Ownership of the underlying memory is ttransferredto the
> + * caller and should be freed using drm_hdcp_helper_destroy().
> + *
> + * Returns:
> + * Pointer to newly created HDCP helper data. PTR_ERR on failure.
> + */
> +struct drm_hdcp_helper_data *
> +drm_hdcp_helper_initialize_dp(struct drm_connector *connector,
> +			      struct drm_dp_aux *aux,
> +			      const struct drm_hdcp_helper_funcs *funcs,
> +			      bool attach_content_type_property)
> +{
> +	struct drm_hdcp_helper_data *out;
> +
> +	out = drm_hdcp_helper_initialize(connector, funcs,
> +					 attach_content_type_property);
> +	if (IS_ERR(out))
> +		return out;
> +
> +	out->aux = aux;
> +	out->hdcp1_lut = &drm_hdcp_hdcp1_dpcd_lut;
> +
> +	return out;
> +}
> +EXPORT_SYMBOL(drm_hdcp_helper_initialize_dp);
> +
> +/**
> + * drm_hdcp_helper_initialize_hdmi - Initializes the HDCP helpers for an HDMI
> + * connector
> + *
> + * @connector: pointer to the HDMI connector.
> + * @funcs: pointer to the vtable of HDCP helper funcs for this connector.
> + * @attach_content_type_property: True if the content_type property should be
> + * attached.
> + *
> + * This function initializes the HDCP helper for the given HDMI connector. This
> + * involves creating the Content Protection property as well as the Content Type
> + * property (if desired). Upon success, it will return a pointer to the HDCP
> + * helper data. Ownership of the underlying memory is transferred to the caller
> + * and should be freed using drm_hdcp_helper_destroy().
> + *
> + * Returns:
> + * Pointer to newly created HDCP helper data. PTR_ERR on failure.
> + */
> +struct drm_hdcp_helper_data *
> +drm_hdcp_helper_initialize_hdmi(struct drm_connector *connector,
> +				const struct drm_hdcp_helper_funcs *funcs,
> +				bool attach_content_type_property)
> +{
> +	struct drm_hdcp_helper_data *out;
> +
> +	out = drm_hdcp_helper_initialize(connector, funcs,
> +					 attach_content_type_property);
> +	if (IS_ERR(out))
> +		return out;
> +
> +	out->hdcp1_lut = &drm_hdcp_hdcp1_ddc_lut;
> +
> +	return out;
> +}
> +EXPORT_SYMBOL(drm_hdcp_helper_initialize_hdmi);
> +
> +/**
> + * drm_hdcp_helper_destroy - Destroys the given HDCP helper data.
> + *
> + * @data: Pointer to the HDCP helper data.
> + *
> + * This function cleans up and destroys the HDCP helper data created by
> + * drm_hdcp_helper_initialize_dp() or drm_hdcp_helper_initialize_hdmi().
> + */
> +void drm_hdcp_helper_destroy(struct drm_hdcp_helper_data *data)
> +{
> +	struct drm_connector *connector;
> +
> +	if (!data)
> +		return;
> +
> +	connector = data->connector;
> +
> +	/*
> +	 * If the connector is registered, it's possible userspace could kick
> +	 * off another HDCP enable, which would re-spawn the workers.
> +	 */
> +	drm_WARN_ON(connector->dev,
> +		    connector->registration_state == DRM_CONNECTOR_REGISTERED);
> +
> +	/*
> +	 * Now that the connector is not registered, check_work won't be run,
> +	 * but cancel any outstanding instances of it
> +	 */
> +	cancel_delayed_work_sync(&data->check_work);
> +
> +	/*
> +	 * We don't cancel prop_work in the same way as check_work since it
> +	 * requires connection_mutex which could be held while calling this
> +	 * function. Instead, we rely on the connector references grabbed before
> +	 * scheduling prop_work to ensure the connector is alive when prop_work
> +	 * is run. So if we're in the destroy path (which is where this
> +	 * function should be called), we're "guaranteed" that prop_work is not
> +	 * active (tl;dr This Should Never Happen).
> +	 */
> +	drm_WARN_ON(connector->dev, work_pending(&data->prop_work));
> +
> +	kfree(data);
> +}
> +EXPORT_SYMBOL(drm_hdcp_helper_destroy);
> diff --git a/include/drm/display/drm_hdcp.h b/include/drm/display/drm_hdcp.h
> index 96a99b1377c0..75694baf72d4 100644
> --- a/include/drm/display/drm_hdcp.h
> +++ b/include/drm/display/drm_hdcp.h
> @@ -36,6 +36,7 @@
>   #define DRM_HDCP_DDC_BKSV			0x00
>   #define DRM_HDCP_DDC_RI_PRIME			0x08
>   #define DRM_HDCP_DDC_AKSV			0x10
> +#define DRM_HDCP_DDC_AINFO			0x15
>   #define DRM_HDCP_DDC_AN				0x18
>   #define DRM_HDCP_DDC_V_PRIME(h)			(0x20 + h * 4)
>   #define DRM_HDCP_DDC_BCAPS			0x40
> @@ -123,6 +124,19 @@
>   #define HDCP_2_2_DEV_COUNT_HI(x)		((x) & BIT(0))
>   #define HDCP_2_2_DEPTH(x)			(((x) & (0x7 << 1)) >> 1)
>   
> +struct drm_hdcp_ksv {
> +	union {
> +		u32 words[2];
> +		u8 bytes[DRM_HDCP_KSV_LEN];
> +	};
> +};
> +struct drm_hdcp_an {
> +	union {
> +		u32 words[2];
> +		u8 bytes[DRM_HDCP_AN_LEN];
> +	};
> +};
> +
>   struct hdcp2_cert_rx {
>   	u8	receiver_id[HDCP_2_2_RECEIVER_ID_LEN];
>   	u8	kpub_rx[HDCP_2_2_K_PUB_RX_LEN];
> @@ -295,4 +309,156 @@ struct hdcp_srm_header {
>   #define DRM_MODE_HDCP_CONTENT_TYPE0		0
>   #define DRM_MODE_HDCP_CONTENT_TYPE1		1
>   
> -#endif
> +struct drm_connector;
> +struct drm_atomic_state;
> +
> +/**
> + * struct drm_hdcp_helper_funcs - A vtable of function hooks for the hdcp helper
> + *
> + * These hooks are used by the hdcp helper to call into the driver/connector
> + * code to read/write to hw.
> + */
> +struct drm_hdcp_helper_funcs {
> +	/**
> +	 * @setup - Performs driver-specific setup before hdcp is enabled
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*setup)(struct drm_connector *connector,
> +		     struct drm_atomic_state *state);

I think all the troubles of the drm/msm code trying to get dp_display 
from drm_connector could have been avoided if this API allowed one to 
pass private data. This is not the case for Intel, but in drm/msm case 
we have a chain of bridges, so establishing a link from connector to the 
driver's private data is not an obvious thing.

> +
> +	/**
> +	 * @are_keys_valid - Checks if the HDCP transmitter keys are valid
> +	 *
> +	 * Returns: true if the display controller has valid keys loaded
> +	 */
> +	bool (*are_keys_valid)(struct drm_connector *connector);
> +
> +	/**
> +	 * @load_keys - Instructs the driver to load its HDCP transmitter keys
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*load_keys)(struct drm_connector *connector);
> +
> +	/**
> +	 * @hdcp2_capable - Checks if both source and sink support HDCP 2.x
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp2_capable)(struct drm_connector *connector, bool *capable);
> +
> +	/**
> +	 * @hdcp2_enable - Enables HDCP 2.x on the specified connector
> +	 *
> +	 * Since we don't have multiple examples of HDCP 2.x enablement, we
> +	 * provide the bare minimum support for HDCP 2.x help. Once we have
> +	 * more examples, perhaps we can be more helpful.
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp2_enable)(struct drm_connector *connector);
> +
> +	/**
> +	 * @hdcp2_check_link - Checks the HDCP 2.x link on a specified connector
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp2_check_link)(struct drm_connector *connector);
> +
> +	/**
> +	 * @hdcp2_disable - Disables HDCP 2.x on the specified connector
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp2_disable)(struct drm_connector *connector);
> +
> +	/**
> +	 * @hdcp1_read_an_aksv - Reads transmitter's An & Aksv from hardware
> +	 *
> +	 * Use this function if hardware allows reading the transmitter's An and
> +	 * Aksv values from the kernel. If your hardware will not allow this,
> +	 * use hdcp1_send_an_aksv() and implement the transmission in the
> +	 * driver.
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp1_read_an_aksv)(struct drm_connector *connector, u32 *an,
> +				  u32 *aksv);
> +
> +	/**
> +	 * @hdcp1_send_an_aksv - Sends transmitter's An & Aksv to the receiver
> +	 *
> +	 * Only implement this on hardware where An or Aksv are not accessible
> +	 * from the kernel. If these values can be read, use
> +	 * hdcp1_read_an_aksv() instead.
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp1_send_an_aksv)(struct drm_connector *connector);
> +
> +	/**
> +	 * @hdcp1_store_receiver_info - Stores the receiver's info in the transmitter
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp1_store_receiver_info)(struct drm_connector *connector,
> +					 u32 *ksv, u32 status, u8 caps,
> +					 bool repeater_present);
> +
> +	/**
> +	 * @hdcp1_enable_encryption - Enables encryption of the outgoing signal
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp1_enable_encryption)(struct drm_connector *connector);
> +
> +	/**
> +	 * @hdcp1_wait_for_r0 - Wait for transmitter to calculate R0
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp1_wait_for_r0)(struct drm_connector *connector);
> +
> +	/**
> +	 * @hdcp1_match_ri - Matches the given Ri from the receiver with Ri in
> +	 * the transmitter
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp1_match_ri)(struct drm_connector *connector, u32 ri_prime);
> +
> +	/**
> +	 * @hdcp1_post_encryption - Allows the driver to confirm encryption and
> +	 * perform any post-processing
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp1_post_encryption)(struct drm_connector *connector);
> +
> +	/**
> +	 * @hdcp1_store_ksv_fifo - Write the receiver's KSV list to transmitter
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp1_store_ksv_fifo)(struct drm_connector *connector,
> +				    u8 *ksv_fifo, u8 num_downstream,
> +				    u8 *bstatus, u32 *vprime);
> +
> +	/**
> +	 * @hdcp1_check_link - Allows the driver to check the HDCP 1.x status
> +	 * on a specified connector
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp1_check_link)(struct drm_connector *connector);
> +
> +	/**
> +	 * @hdcp1_disable - Disables HDCP 1.x on the specified connector
> +	 *
> +	 * Returns: 0 on success, -errno on failure
> +	 */
> +	int (*hdcp1_disable)(struct drm_connector *connector);
> +};
> +
> +#endif  // INCLUDE_DRM_DISPLAY_DRM_HDCP_H_
> diff --git a/include/drm/display/drm_hdcp_helper.h b/include/drm/display/drm_hdcp_helper.h
> index cb2cc5002f65..dbbaced148f2 100644
> --- a/include/drm/display/drm_hdcp_helper.h
> +++ b/include/drm/display/drm_hdcp_helper.h
> @@ -15,11 +15,39 @@ struct drm_atomic_state;
>   struct drm_device;
>   struct drm_connector;
>   
> +struct drm_hdcp_helper_data;
> +struct drm_dp_aux;
> +struct i2c_adapter;
> +struct mutex;
> +
>   int drm_hdcp_check_ksvs_revoked(struct drm_device *dev, u8 *ksvs, u32 ksv_count);
>   int drm_connector_attach_content_protection_property(struct drm_connector *connector,
>   						     bool hdcp_content_type);
>   void drm_hdcp_update_content_protection(struct drm_connector *connector, u64 val);
>   bool drm_hdcp_atomic_check(struct drm_connector *connector,
>   			   struct drm_atomic_state *state);
> +void drm_hdcp_atomic_commit(struct drm_atomic_state *state,
> +			    struct drm_connector *connector);
> +
> +struct drm_hdcp_helper_data *
> +drm_hdcp_helper_initialize_dp(struct drm_connector *connector,
> +			      struct drm_dp_aux *aux,
> +			      const struct drm_hdcp_helper_funcs *funcs,
> +			      bool attach_content_type_property);
> +
> +struct drm_hdcp_helper_data *
> +drm_hdcp_helper_initialize_hdmi(struct drm_connector *connector,
> +				const struct drm_hdcp_helper_funcs *funcs,
> +				bool attach_content_type_property);
> +
> +void drm_hdcp_helper_destroy(struct drm_hdcp_helper_data *data);
> +
> +int drm_hdcp_helper_hdcp1_capable(struct drm_hdcp_helper_data *data,
> +				  bool *capable);
> +void drm_hdcp_helper_atomic_commit(struct drm_hdcp_helper_data *data,
> +				   struct drm_atomic_state *state,
> +				   struct mutex *driver_mutex);
> +
> +void drm_hdcp_helper_schedule_hdcp_check(struct drm_hdcp_helper_data *data);
>   
> -#endif
> +#endif  // INCLUDE_DRM_DISPLAY_DRM_HDCP_HELPER_H_"

Not related.

-- 
With best wishes
Dmitry