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References: <20220111112701.1064458-1-hsinyi@chromium.org> <20220111112701.1064458-2-hsinyi@chromium.org>
 <20220113034008.GC2478030@anxtwsw-Precision-3640-Tower>
In-Reply-To: <20220113034008.GC2478030@anxtwsw-Precision-3640-Tower>
From:   Hsin-Yi Wang <hsinyi@chromium.org>
Date:   Thu, 13 Jan 2022 15:36:27 +0800
Message-ID: <CAJMQK-gt5_L24VWerc6rGK-GVijyaeo0w-xDg8L2mE5eFSPvEA@mail.gmail.com>
Subject: Re: [PATCH 2/3] drm/bridge: anx7625: Support reading edid through aux channel
To:     Xin Ji <xji@analogixsemi.com>
Cc:     Robert Foss <robert.foss@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, Andrzej Hajda <a.hajda@samsung.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Sam Ravnborg <sam@ravnborg.org>,
        Maxime Ripard <maxime@cerno.tech>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Thu, Jan 13, 2022 at 11:40 AM Xin Ji <xji@analogixsemi.com> wrote:
>
> Hi Hsin-Yi, thanks for the patch! Please fix the follow comment, then
> add my id.
> Reviewed-by: Xin Ji <xji@analogixsemi.com>
>
> On Tue, Jan 11, 2022 at 07:27:00PM +0800, Hsin-Yi Wang wrote:
> > Support reading edid through aux channel if panel is connected to aux
> > bus. Extend anx7625_aux_dpcd_trans() to implement aux transfer function:
> >
> > 1. panel is populated in devm_of_dp_aux_populate_ep_devices(), so move
> >    anx7625_parse_dt() after.
> > 2. Use pm runtime autosuspend since aux transfer function is called
> >    multiple times when reading edid.
> > 3. No-op if aux transfer length is 0.
> >
> > Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> > ---
> > This patch is based on drm-misc-next and depends on
> > https://patchwork.freedesktop.org/patch/469081/
> > ---
> >  drivers/gpu/drm/bridge/analogix/anx7625.c | 123 ++++++++++++++++++----
> >  drivers/gpu/drm/bridge/analogix/anx7625.h |   4 +
> >  2 files changed, 109 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> > index dbe708eb3bcf11..d60cfc058fbe7d 100644
> > --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> > @@ -24,6 +24,7 @@
> >  #include <drm/drm_atomic_helper.h>
> >  #include <drm/drm_bridge.h>
> >  #include <drm/drm_crtc_helper.h>
> > +#include <drm/drm_dp_aux_bus.h>
> >  #include <drm/drm_dp_helper.h>
> >  #include <drm/drm_edid.h>
> >  #include <drm/drm_hdcp.h>
> > @@ -231,19 +232,22 @@ static int wait_aux_op_finish(struct anx7625_data *ctx)
> >       return 0;
> >  }
> >
> > -static int anx7625_aux_dpcd_trans(struct anx7625_data *ctx, u8 op,
> > -                               u32 address, u8 len, u8 *buf)
> > +static int anx7625_aux_trans(struct anx7625_data *ctx, u8 op, u32 address,
> > +                          u8 len, u8 *buf)
> >  {
> >       struct device *dev = &ctx->client->dev;
> >       int ret;
> >       u8 addrh, addrm, addrl;
> >       u8 cmd;
> >
> > -     if (len > MAX_DPCD_BUFFER_SIZE) {
> > +     if (len > DP_AUX_MAX_PAYLOAD_BYTES) {
> >               dev_err(dev, "exceed aux buffer len.\n");
> >               return -EINVAL;
>
> The native write command is 0x08, I2C Over aux write command is 0x04.
> The native read command is 0x09, I2C Over aux read command is 0x05.
Thanks for the review, the command for native read/write is updated.

v2 is sent.

>
> >       }
> >
> > +     if (!len)
> > +             return len;
> > +
> >       addrl = address & 0xFF;
> >       addrm = (address >> 8) & 0xFF;
> >       addrh = (address >> 16) & 0xFF;
> > @@ -262,7 +266,7 @@ static int anx7625_aux_dpcd_trans(struct anx7625_data *ctx, u8 op,
> >       ret |= anx7625_reg_write(ctx, ctx->i2c.rx_p0_client,
> >                                AP_AUX_ADDR_19_16, addrh);
> >
> > -     if (op == DPCD_WRITE)
> > +     if (op == DPCD_WRITE || op == AP_AUX_WRITE)
> >               ret |= anx7625_reg_block_write(ctx, ctx->i2c.rx_p0_client,
> >                                              AP_AUX_BUFF_START, len, buf);
> >       /* Enable aux access */
> > @@ -275,14 +279,14 @@ static int anx7625_aux_dpcd_trans(struct anx7625_data *ctx, u8 op,
> >       }
> >
> >       ret = wait_aux_op_finish(ctx);
> > -     if (ret) {
> > +     if (ret < 0) {
> >               dev_err(dev, "aux IO error: wait aux op finish.\n");
> >               return ret;
> >       }
> >
> >       /* Write done */
> > -     if (op == DPCD_WRITE)
> > -             return 0;
> > +     if (op == DPCD_WRITE || op == AP_AUX_WRITE)
> > +             return len;
> >
> >       /* Read done, read out dpcd data */
> >       ret = anx7625_reg_block_read(ctx, ctx->i2c.rx_p0_client,
> > @@ -292,7 +296,7 @@ static int anx7625_aux_dpcd_trans(struct anx7625_data *ctx, u8 op,
> >               return -EIO;
> >       }
> >
> > -     return 0;
> > +     return len;
> >  }
> >
> >  static int anx7625_video_mute_control(struct anx7625_data *ctx,
> > @@ -867,7 +871,7 @@ static int anx7625_hdcp_enable(struct anx7625_data *ctx)
> >       }
> >
> >       /* Read downstream capability */
> > -     anx7625_aux_dpcd_trans(ctx, DPCD_READ, 0x68028, 1, &bcap);
> > +     anx7625_aux_trans(ctx, DPCD_READ, 0x68028, 1, &bcap);
> >       if (!(bcap & 0x01)) {
> >               pr_warn("downstream not support HDCP 1.4, cap(%x).\n", bcap);
> >               return 0;
> > @@ -956,7 +960,7 @@ static void anx7625_dp_stop(struct anx7625_data *ctx)
> >       dev_dbg(dev, "notify downstream enter into standby\n");
> >       /* Downstream monitor enter into standby mode */
> >       data = 2;
> > -     ret |= anx7625_aux_dpcd_trans(ctx, DPCD_WRITE, 0x000600, 1, &data);
> > +     ret |= anx7625_aux_trans(ctx, DPCD_WRITE, 0x000600, 1, &data);
> >       if (ret < 0)
> >               DRM_DEV_ERROR(dev, "IO error : mute video fail\n");
> >
> > @@ -1655,11 +1659,60 @@ static int anx7625_parse_dt(struct device *dev,
> >       return 0;
> >  }
> >
> > +static bool anx7625_of_panel_on_aux_bus(struct device *dev)
> > +{
> > +     struct device_node *bus, *panel;
> > +
> > +     bus = of_get_child_by_name(dev->of_node, "aux-bus");
> > +     if (!bus)
> > +             return false;
> > +
> > +     panel = of_get_child_by_name(bus, "panel");
> > +     of_node_put(bus);
> > +     if (!panel)
> > +             return false;
> > +     of_node_put(panel);
> > +
> > +     return true;
> > +}
> > +
> >  static inline struct anx7625_data *bridge_to_anx7625(struct drm_bridge *bridge)
> >  {
> >       return container_of(bridge, struct anx7625_data, bridge);
> >  }
> >
> > +static ssize_t anx7625_aux_transfer(struct drm_dp_aux *aux,
> > +                                    struct drm_dp_aux_msg *msg)
> > +{
> > +     struct anx7625_data *ctx = container_of(aux, struct anx7625_data, aux);
> > +     struct device *dev = &ctx->client->dev;
> > +     u8 request = msg->request & ~DP_AUX_I2C_MOT, op;
> > +     int ret = 0;
> > +
> > +     pm_runtime_get_sync(dev);
> > +     msg->reply = 0;
> > +     switch (request) {
> > +     case DP_AUX_NATIVE_WRITE:
> > +     case DP_AUX_I2C_WRITE:
> > +             op = AP_AUX_WRITE;
>
> The DPCD native write is different with I2C over aux write.
>
> > +             break;
> > +     case DP_AUX_NATIVE_READ:
> > +     case DP_AUX_I2C_READ:
> > +             op = AP_AUX_READ;
> The DPCD native read is different with I2C over aux read.
> > +             break;
> > +     default:
> > +             ret = -EINVAL;
> > +     }
> > +     if (!ret) {
> > +             ret = anx7625_aux_trans(ctx, op, msg->address, msg->size,
> > +                                     msg->buffer);
> > +     }
> > +     pm_runtime_mark_last_busy(dev);
> > +     pm_runtime_put_autosuspend(dev);
> > +
> > +     return ret;
> > +}
> > +
> >  static struct edid *anx7625_get_edid(struct anx7625_data *ctx)
> >  {
> >       struct device *dev = &ctx->client->dev;
> > @@ -2066,6 +2119,13 @@ static int anx7625_bridge_attach(struct drm_bridge *bridge,
> >               return -ENODEV;
> >       }
> >
> > +     ctx->aux.drm_dev = bridge->dev;
> > +     err = drm_dp_aux_register(&ctx->aux);
> > +     if (err) {
> > +             dev_err(dev, "failed to register aux channel: %d\n", err);
> > +             return err;
> > +     }
> > +
> >       if (ctx->pdata.panel_bridge) {
> >               err = drm_bridge_attach(bridge->encoder,
> >                                       ctx->pdata.panel_bridge,
> > @@ -2079,6 +2139,13 @@ static int anx7625_bridge_attach(struct drm_bridge *bridge,
> >       return 0;
> >  }
> >
> > +static void anx7625_bridge_detach(struct drm_bridge *bridge)
> > +{
> > +     struct anx7625_data *ctx = bridge_to_anx7625(bridge);
> > +
> > +     drm_dp_aux_unregister(&ctx->aux);
> > +}
> > +
> >  static enum drm_mode_status
> >  anx7625_bridge_mode_valid(struct drm_bridge *bridge,
> >                         const struct drm_display_info *info,
> > @@ -2344,6 +2411,7 @@ static struct edid *anx7625_bridge_get_edid(struct drm_bridge *bridge,
> >
> >  static const struct drm_bridge_funcs anx7625_bridge_funcs = {
> >       .attach = anx7625_bridge_attach,
> > +     .detach = anx7625_bridge_detach,
> >       .mode_valid = anx7625_bridge_mode_valid,
> >       .mode_set = anx7625_bridge_mode_set,
> >       .atomic_check = anx7625_bridge_atomic_check,
> > @@ -2501,6 +2569,12 @@ static const struct dev_pm_ops anx7625_pm_ops = {
> >                          anx7625_runtime_pm_resume, NULL)
> >  };
> >
> > +static void anx7625_runtime_disable(void *data)
> > +{
> > +     pm_runtime_dont_use_autosuspend(data);
> > +     pm_runtime_disable(data);
> > +}
> > +
> >  static int anx7625_i2c_probe(struct i2c_client *client,
> >                            const struct i2c_device_id *id)
> >  {
> > @@ -2523,13 +2597,6 @@ static int anx7625_i2c_probe(struct i2c_client *client,
> >
> >       pdata = &platform->pdata;
> >
> > -     ret = anx7625_parse_dt(dev, pdata);
> > -     if (ret) {
> > -             if (ret != -EPROBE_DEFER)
> > -                     DRM_DEV_ERROR(dev, "fail to parse DT : %d\n", ret);
> > -             return ret;
> > -     }
> > -
> >       platform->client = client;
> >       i2c_set_clientdata(client, platform);
> >
> > @@ -2577,6 +2644,19 @@ static int anx7625_i2c_probe(struct i2c_client *client,
> >               }
> >       }
> >
> > +     platform->aux.name = "anx7625-aux";
> > +     platform->aux.dev = dev;
> > +     platform->aux.transfer = anx7625_aux_transfer;
> > +     drm_dp_aux_init(&platform->aux);
> > +     devm_of_dp_aux_populate_ep_devices(&platform->aux);
> > +
> > +     ret = anx7625_parse_dt(dev, pdata);
> > +     if (ret) {
> > +             if (ret != -EPROBE_DEFER)
> > +                     DRM_DEV_ERROR(dev, "fail to parse DT : %d\n", ret);
> > +             return ret;
> > +     }
> > +
> >       if (anx7625_register_i2c_dummy_clients(platform, client) != 0) {
> >               ret = -ENOMEM;
> >               DRM_DEV_ERROR(dev, "fail to reserve I2C bus.\n");
> > @@ -2584,6 +2664,12 @@ static int anx7625_i2c_probe(struct i2c_client *client,
> >       }
> >
> >       pm_runtime_enable(dev);
> > +     pm_runtime_set_autosuspend_delay(dev, 1000);
> > +     pm_runtime_use_autosuspend(dev);
> > +     pm_suspend_ignore_children(dev, true);
> > +     ret = devm_add_action_or_reset(dev, anx7625_runtime_disable, dev);
> > +     if (ret)
> > +             return ret;
> >
> >       if (!platform->pdata.low_power_mode) {
> >               anx7625_disable_pd_protocol(platform);
> > @@ -2596,7 +2682,8 @@ static int anx7625_i2c_probe(struct i2c_client *client,
> >
> >       platform->bridge.funcs = &anx7625_bridge_funcs;
> >       platform->bridge.of_node = client->dev.of_node;
> > -     platform->bridge.ops = DRM_BRIDGE_OP_EDID;
> > +     if (!anx7625_of_panel_on_aux_bus(&client->dev))
> > +             platform->bridge.ops |= DRM_BRIDGE_OP_EDID;
> >       if (!platform->pdata.panel_bridge)
> >               platform->bridge.ops |= DRM_BRIDGE_OP_HPD |
> >                                       DRM_BRIDGE_OP_DETECT;
> > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.h b/drivers/gpu/drm/bridge/analogix/anx7625.h
> > index 56165f5b254c14..cab19735c22e21 100644
> > --- a/drivers/gpu/drm/bridge/analogix/anx7625.h
> > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.h
> > @@ -231,6 +231,9 @@
> >  #define AP_AUX_ADDR_15_8  0x12
> >  #define AP_AUX_ADDR_19_16 0x13
> >
> > +#define AP_AUX_READ 0x1
> > +#define AP_AUX_WRITE 0x4
> > +
> >  /* Bit[0:3] AUX status, bit 4 op_en, bit 5 address only */
> >  #define AP_AUX_CTRL_STATUS 0x14
> >  #define AP_AUX_CTRL_OP_EN 0x10
> > @@ -474,6 +477,7 @@ struct anx7625_data {
> >       u8 bridge_attached;
> >       struct drm_connector *connector;
> >       struct mipi_dsi_device *dsi;
> > +     struct drm_dp_aux aux;
> >  };
> >
> >  #endif  /* __ANX7625_H__ */
> > --
> > 2.34.1.575.g55b058a8bb-goog