by Jernej Škrabec

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Subject: Re: [PATCH RFC v2 07/37] drm/connector: hdmi: Add HDMI compute clock helper

Hi Maxime!

Dne sreda, 20. september 2023 ob 16:35:22 CEST je Maxime Ripard napisal(a):
> A lot of HDMI drivers have some variation of the formula to calculate
> the TMDS character rate from a mode, but few of them actually take all
> parameters into account.
>
> Let's create a helper to provide that rate taking all parameters into
> account.
>
> Signed-off-by: Maxime Ripard <[email protected]>
> ---
> drivers/gpu/drm/drm_connector.c | 31 +++++++++++++++++++++++++++++++
> include/drm/drm_connector.h | 5 +++++
> 2 files changed, 36 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index b01cb4783ea6..4c1af97971bb 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -2944,6 +2944,37 @@ void drm_connector_update_privacy_screen(const struct drm_connector_state *conne
> }
> EXPORT_SYMBOL(drm_connector_update_privacy_screen);
>
> +/**
> + * drm_connector_hdmi_compute_mode_clock() - Computes the TMDS Character Rate
> + * @mode: Display mode to compute the clock for
> + * @bpc: Bits per character
> + * @fmt: Output Pixel Format used
> + *
> + * Returns the TMDS Character Rate for a given mode, bpc count and output format.
> + *
> + * RETURNS:
> + * The TMDS Character Rate, in Hertz
> + */
> +unsigned long long
> +drm_connector_hdmi_compute_mode_clock(const struct drm_display_mode *mode,
> + unsigned int bpc,
> + enum hdmi_colorspace fmt)
> +{
> + unsigned long long clock = mode->clock * 1000ULL;
> +
> + if (mode->flags & DRM_MODE_FLAG_DBLCLK)
> + clock = clock * 2;
> +
> + if (fmt == HDMI_COLORSPACE_YUV422)
> + bpc = 8;

I think you're missing YUV420 handling, which needs half of clock speed. But
this is a thing of HDMI2.

Best regards,
Jernej

> +
> + clock = clock * bpc;
> + do_div(clock, 8);
> +
> + return clock;
> +}
> +EXPORT_SYMBOL(drm_connector_hdmi_compute_mode_clock);
> +
> int drm_connector_set_obj_prop(struct drm_mode_object *obj,
> struct drm_property *property,
> uint64_t value)
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index a66cb4e35d7b..d74e9c64ee88 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -38,6 +38,7 @@ struct drm_connector_helper_funcs;
> struct drm_modeset_acquire_ctx;
> struct drm_device;
> struct drm_crtc;
> +struct drm_display_mode;
> struct drm_encoder;
> struct drm_panel;
> struct drm_property;
> @@ -2115,6 +2116,10 @@ void drm_connector_attach_privacy_screen_properties(struct drm_connector *conn);
> void drm_connector_attach_privacy_screen_provider(
> struct drm_connector *connector, struct drm_privacy_screen *priv);
> void drm_connector_update_privacy_screen(const struct drm_connector_state *connector_state);
> +unsigned long long
> +drm_connector_hdmi_compute_mode_clock(const struct drm_display_mode *mode,
> + unsigned int bpc,
> + enum hdmi_colorspace fmt);
>
> /**
> * struct drm_tile_group - Tile group metadata
>
>

2023-09-21 21:49:29

Hi Hans,

On Thu, Sep 21, 2023 at 06:29:29PM +0200, Hans Verkuil wrote:
> On 20/09/2023 16:35, Maxime Ripard wrote:
> > Hi,
> >
> > Here's a series that creates a subclass of drm_connector specifically
> > targeted at HDMI controllers.
> >
> > The idea behind this series came from a recent discussion on IRC during
> > which we discussed infoframes generation of i915 vs everything else.
> >
> > Infoframes generation code still requires some decent boilerplate, with
> > each driver doing some variation of it.
> >
> > In parallel, while working on vc4, we ended up converting a lot of i915
> > logic (mostly around format / bpc selection, and scrambler setup) to
> > apply on top of a driver that relies only on helpers.
> >
> > While currently sitting in the vc4 driver, none of that logic actually
> > relies on any driver or hardware-specific behaviour.
> >
> > The only missing piece to make it shareable are a bunch of extra
> > variables stored in a state (current bpc, format, RGB range selection,
> > etc.).
> >
> > The initial implementation was relying on some generic subclass of
> > drm_connector to address HDMI connectors, with a bunch of helpers that
> > will take care of all the "HDMI Spec" related code. Scrambler setup is
> > missing at the moment but can easily be plugged in.
> >
> > The feedback was that creating a connector subclass like was done for
> > writeback would prevent the adoption of those helpers since it couldn't
> > be used in all situations (like when the connector driver can implement
> > multiple output) and required more churn to cast between the
> > drm_connector and its subclass. The decision was thus to provide a set
> > of helper and to store the required variables in drm_connector and
> > drm_connector_state. This what has been implemented now.
> >
> > Hans Verkuil also expressed interest in implementing a mechanism in v4l2
> > to retrieve infoframes from HDMI receiver and implementing an
> > infoframe-decode tool.
>
> I'd love to get started on that, but...
>
> >
> > This series thus leverages the infoframe generation code to expose it
> > through debugfs.
> >
> > This entire series is only build-tested at the moment. Let me know what
> > you think,
>
> ...trying this series on my RPi4 gives me this during boot:
>
> [ 2.361239] vc4-drm gpu: bound fe400000.hvs (ops 0xffff800080cac6f8)
> [ 2.367834] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000090
> [ 2.376748] Mem abort info:
> [ 2.379570] ESR = 0x0000000096000044
> [ 2.383367] EC = 0x25: DABT (current EL), IL = 32 bits
> [ 2.388748] SET = 0, FnV = 0
> [ 2.391835] EA = 0, S1PTW = 0
> [ 2.395011] FSC = 0x04: level 0 translation fault
> [ 2.399951] Data abort info:
> [ 2.402864] ISV = 0, ISS = 0x00000044, ISS2 = 0x00000000
> [ 2.408420] CM = 0, WnR = 1, TnD = 0, TagAccess = 0
> [ 2.413536] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
> [ 2.418916] [0000000000000090] user address but active_mm is swapper
> [ 2.425353] Internal error: Oops: 0000000096000044 [#1] PREEMPT SMP
> [ 2.431700] Modules linked in:
> [ 2.434791] CPU: 2 PID: 55 Comm: kworker/u8:3 Not tainted 6.6.0-rc1-hdmi-dbg #245
> [ 2.442372] Hardware name: Raspberry Pi 4 Model B Rev 1.4 (DT)
> [ 2.448278] Workqueue: events_unbound deferred_probe_work_func
> [ 2.454193] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 2.461245] pc : drm_connector_attach_max_bpc_property+0x48/0x90
> [ 2.467332] lr : drm_connector_attach_max_bpc_property+0x3c/0x90
> [ 2.473415] sp : ffff800081d038b0
> [ 2.476766] x29: ffff800081d038b0 x28: 0000000000000000 x27: ffff0001041968c0
> [ 2.483999] x26: 0000000000000000 x25: ffff00010339d558 x24: ffff000103399000
> [ 2.491231] x23: ffff800080caa3e8 x22: ffff800080e96a20 x21: 000000000000000c
> [ 2.498463] x20: 000000000000000c x19: ffff00010339d558 x18: ffffffffffffffff
> [ 2.505694] x17: ffff0001008e7650 x16: ffff800080d55500 x15: ffffffffffffffff
> [ 2.512926] x14: ffff000105dda209 x13: 0000000000000006 x12: 0000000000000001
> [ 2.520158] x11: 0101010101010101 x10: ffff00027effe219 x9 : 0000000000000001
> [ 2.527389] x8 : ffff000105db8ad4 x7 : 00000000c0c0c0c0 x6 : 00000000c0c0c0c0
> [ 2.534620] x5 : 0000000000000000 x4 : ffff00010339d728 x3 : ffff00010339d728
> [ 2.541852] x2 : 000000000000000c x1 : 0000000000000000 x0 : 0000000000000000
> [ 2.549083] Call trace:
> [ 2.551554] drm_connector_attach_max_bpc_property+0x48/0x90
> [ 2.557285] drmm_connector_hdmi_init+0x114/0x14c
> [ 2.562048] vc4_hdmi_bind+0x320/0xa40
> [ 2.565842] component_bind_all+0x114/0x23c
> [ 2.570077] vc4_drm_bind+0x148/0x2c0
> [ 2.573784] try_to_bring_up_aggregate_device+0x168/0x1d4
> [ 2.579253] __component_add+0xa4/0x16c
> [ 2.583136] component_add+0x14/0x20
> [ 2.586754] vc4_hdmi_dev_probe+0x1c/0x28
> [ 2.590815] platform_probe+0x68/0xc4
> [ 2.594522] really_probe+0x148/0x2b0
> [ 2.598228] __driver_probe_device+0x78/0x12c
> [ 2.602638] driver_probe_device+0xd8/0x15c
> [ 2.606873] __device_attach_driver+0xb8/0x134
> [ 2.611372] bus_for_each_drv+0x80/0xdc
> [ 2.615254] __device_attach+0x9c/0x188
> [ 2.619136] device_initial_probe+0x14/0x20
> [ 2.623371] bus_probe_device+0xac/0xb0
> [ 2.627253] deferred_probe_work_func+0x88/0xc0
> [ 2.631839] process_one_work+0x138/0x244
> [ 2.635899] worker_thread+0x320/0x438
> [ 2.639692] kthread+0x10c/0x110
> [ 2.642957] ret_from_fork+0x10/0x20
> [ 2.646576] Code: 94005f8d 12001e94 f9427e61 52800000 (39024034)
> [ 2.652745] ---[ end trace 0000000000000000 ]---

Well, I guess I'll have to start testing what I'm doing then :)

Maxime

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2023-09-22 02:30:37

by Pekka Paalanen

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Subject: Re: [PATCH RFC v2 03/37] drm/connector: hdmi: Add Broadcast RGB property

On Wed, 20 Sep 2023 16:35:18 +0200
Maxime Ripard <[email protected]> wrote:

> The i915 driver has a property to force the RGB range of an HDMI output.
> The vc4 driver then implemented the same property with the same
> semantics. KWin has support for it, and a PR for mutter is also there to
> support it.
>
> Both drivers implementing the same property with the same semantics,
> plus the userspace having support for it, is proof enough that it's
> pretty much a de-facto standard now and we can provide helpers for it.
>
> Let's plumb it into the newly created HDMI connector.
>
> Signed-off-by: Maxime Ripard <[email protected]>
> ---
> Documentation/gpu/kms-properties.csv | 1 -
> drivers/gpu/drm/drm_atomic.c | 5 +++
> drivers/gpu/drm/drm_atomic_state_helper.c | 17 +++++++
> drivers/gpu/drm/drm_atomic_uapi.c | 4 ++
> drivers/gpu/drm/drm_connector.c | 74 +++++++++++++++++++++++++++++++
> include/drm/drm_connector.h | 39 ++++++++++++++++
> 6 files changed, 139 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/gpu/kms-properties.csv b/Documentation/gpu/kms-properties.csv
> index 0f9590834829..caef14c532d4 100644
> --- a/Documentation/gpu/kms-properties.csv
> +++ b/Documentation/gpu/kms-properties.csv
> @@ -17,7 +17,6 @@ Owner Module/Drivers,Group,Property Name,Type,Property Values,Object attached,De
> ,Virtual GPU,“suggested X”,RANGE,"Min=0, Max=0xffffffff",Connector,property to suggest an X offset for a connector
> ,,“suggested Y”,RANGE,"Min=0, Max=0xffffffff",Connector,property to suggest an Y offset for a connector
> ,Optional,"""aspect ratio""",ENUM,"{ ""None"", ""4:3"", ""16:9"" }",Connector,TDB
> -i915,Generic,"""Broadcast RGB""",ENUM,"{ ""Automatic"", ""Full"", ""Limited 16:235"" }",Connector,"When this property is set to Limited 16:235 and CTM is set, the hardware will be programmed with the result of the multiplication of CTM by the limited range matrix to ensure the pixels normally in the range 0..1.0 are remapped to the range 16/255..235/255."

Hi,

have a look at this old doc for the property, and...

> ,,“audio”,ENUM,"{ ""force-dvi"", ""off"", ""auto"", ""on"" }",Connector,TBD
> ,SDVO-TV,“mode”,ENUM,"{ ""NTSC_M"", ""NTSC_J"", ""NTSC_443"", ""PAL_B"" } etc.",Connector,TBD
> ,,"""left_margin""",RANGE,"Min=0, Max= SDVO dependent",Connector,TBD

...

> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index d9a7e101e4e5..b45471d540ac 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -1174,6 +1174,29 @@ static const u32 dp_colorspaces =
> BIT(DRM_MODE_COLORIMETRY_BT2020_CYCC) |
> BIT(DRM_MODE_COLORIMETRY_BT2020_YCC);
>
> +static const struct drm_prop_enum_list broadcast_rgb_names[] = {
> + { DRM_HDMI_BROADCAST_RGB_AUTO, "Automatic" },
> + { DRM_HDMI_BROADCAST_RGB_FULL, "Full" },
> + { DRM_HDMI_BROADCAST_RGB_LIMITED, "Limited 16:235" },
> +};
> +
> +/*
> + * drm_hdmi_connector_get_broadcast_rgb_name - Return a string for HDMI connector RGB broadcast selection
> + * @broadcast_rgb: Broadcast RGB selection to compute name of
> + *
> + * Returns: the name of the Broadcast RGB selection, or NULL if the type
> + * is not valid.
> + */
> +const char *
> +drm_hdmi_connector_get_broadcast_rgb_name(enum drm_hdmi_broadcast_rgb broadcast_rgb)
> +{
> + if (broadcast_rgb > DRM_HDMI_BROADCAST_RGB_LIMITED)
> + return NULL;
> +
> + return broadcast_rgb_names[broadcast_rgb].name;
> +}
> +EXPORT_SYMBOL(drm_hdmi_connector_get_broadcast_rgb_name);
> +
> /**
> * DOC: standard connector properties
> *
> @@ -1640,6 +1663,24 @@ EXPORT_SYMBOL(drm_connector_attach_dp_subconnector_property);
> /**
> * DOC: HDMI connector properties
> *
> + * Broadcast RGB (HDMI Specific):
> + * Indicates the RGB Range (Full vs Limited) used.
> + *
> + * The value of this property can be one of the following:
> + *
> + * Automatic:
> + * RGB Range is selected automatically based on the mode
> + * according to the HDMI specifications.
> + *
> + * Full:
> + * Full RGB Range is forced.
> + *
> + * Limited 16:235:
> + * Limited RGB Range is forced.
> + *
> + * Drivers can set up this property by calling
> + * drm_connector_attach_broadcast_rgb_property().

...compare it to this. There is one crucial detail lost: setting this
property does two or three things: it clips conversion input values to
[0.0, 1.0] range, programs a conversion matrix to convert full-range
RGB to destination RGB, and sends infoframes to indicate the chosen
destination RGB.

The distinction is important, because use cases like PLUGE calibration
(Rec. ITU-R BT.814-4) rely on indicating limited range while pixel
values are still able to carry sub-black values. Other procedures might
also want to use super-whites. This is impossible with the existing
"Broadcast RGB" property, but that is a different matter.

The old doc didn't exactly say it sets the infoframe fields either, but
I presume it does.

I feel the documentation needs to be much more explicit here.

> + *
> * content type (HDMI specific):
> * Indicates content type setting to be used in HDMI infoframes to indicate
> * content type for the external device, so that it adjusts its display
> @@ -2500,6 +2541,39 @@ int drm_connector_attach_hdr_output_metadata_property(struct drm_connector *conn
> }
> EXPORT_SYMBOL(drm_connector_attach_hdr_output_metadata_property);
>
> +/**
> + * drm_connector_attach_broadcast_rgb_property - attach "Broadcast RGB" property
> + * @connector: connector to attach max bpc property on.

"max bpc" pasta.

> + *
> + * This is used to add support for forcing the RGB range on a connector
> + *
> + * Returns:
> + * Zero on success, negative errno on failure.
> + */
> +int drm_connector_attach_broadcast_rgb_property(struct drm_connector *connector)
> +{
> + struct drm_device *dev = connector->dev;
> + struct drm_property *prop;
> +
> + prop = connector->broadcast_rgb_property;
> + if (!prop) {
> + prop = drm_property_create_enum(dev, DRM_MODE_PROP_ENUM,
> + "Broadcast RGB",
> + broadcast_rgb_names,
> + ARRAY_SIZE(broadcast_rgb_names));
> + if (!prop)
> + return -EINVAL;
> +
> + connector->broadcast_rgb_property = prop;
> + }
> +
> + drm_object_attach_property(&connector->base, prop,
> + DRM_HDMI_BROADCAST_RGB_AUTO);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_connector_attach_broadcast_rgb_property);
> +
> /**
> * drm_connector_attach_colorspace_property - attach "Colorspace" property
> * @connector: connector to attach the property on.
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 5961f2ad48b1..fdcf64ab91a9 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -368,6 +368,33 @@ enum drm_panel_orientation {
> DRM_MODE_PANEL_ORIENTATION_RIGHT_UP,
> };
>
> +/**
> + * enum drm_hdmi_broadcast_rgb - Broadcast RGB Selection for a @drm_hdmi_connector
> + *
> + * This enum is used to track broadcast RGB selection. There are no
> + * separate #defines for the uapi!

Why the "no separate defines" comment? That's the norm.

The KMS property UAPI works by string names for enum values. Some enum
properties might expose C enums for the values, but that is an
exception that cannot be fixed due to stable UAPI.

Thanks,
pq

> + */
> +enum drm_hdmi_broadcast_rgb {
> + /**
> + * @DRM_HDMI_BROADCAST_RGB_AUTO: The RGB range is selected
> + * automatically based on the mode.
> + */
> + DRM_HDMI_BROADCAST_RGB_AUTO,
> +
> + /**
> + * @DRM_HDMI_BROADCAST_RGB_FULL: Full range RGB is forced.
> + */
> + DRM_HDMI_BROADCAST_RGB_FULL,
> +
> + /**
> + * @DRM_HDMI_BROADCAST_RGB_LIMITED: Limited range RGB is forced.
> + */
> + DRM_HDMI_BROADCAST_RGB_LIMITED,
> +};

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2023-09-22 02:54:59

by Jani Nikula

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Subject: Re: [PATCH RFC v2 05/37] drm/connector: hdmi: Add output BPC to the connector state

On Thu, 21 Sep 2023, Pekka Paalanen <[email protected]> wrote:
> On Wed, 20 Sep 2023 16:35:20 +0200
> Maxime Ripard <[email protected]> wrote:
>
>> We'll add automatic selection of the output BPC in a following patch,
>> but let's add it to the HDMI connector state already.
>>
>> Signed-off-by: Maxime Ripard <[email protected]>
>> ---
>> drivers/gpu/drm/drm_atomic.c | 4 +++-
>> drivers/gpu/drm/drm_atomic_state_helper.c | 6 +++++-
>> drivers/gpu/drm/drm_connector.c | 13 ++++++++++++-
>> include/drm/drm_connector.h | 13 ++++++++++++-
>> 4 files changed, 32 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
>> index b1b56dcaa76b..8dce0a2f2ac3 100644
>> --- a/drivers/gpu/drm/drm_atomic.c
>> +++ b/drivers/gpu/drm/drm_atomic.c
>> @@ -1143,9 +1143,11 @@ static void drm_atomic_connector_print_state(struct drm_printer *p,
>> drm_printf(p, "\tcolorspace=%s\n", drm_get_colorspace_name(state->colorspace));
>>
>> if (connector->connector_type == DRM_MODE_CONNECTOR_HDMIA ||
>> - connector->connector_type == DRM_MODE_CONNECTOR_HDMIB)
>> + connector->connector_type == DRM_MODE_CONNECTOR_HDMIB) {
>> drm_printf(p, "\tbroadcast_rgb=%s\n",
>> drm_hdmi_connector_get_broadcast_rgb_name(state->hdmi.broadcast_rgb));
>> + drm_printf(p, "\toutput_bpc=%u\n", state->hdmi.output_bpc);
>> + }
>>
>> if (connector->connector_type == DRM_MODE_CONNECTOR_WRITEBACK)
>> if (state->writeback_job && state->writeback_job->fb)
>> diff --git a/drivers/gpu/drm/drm_atomic_state_helper.c b/drivers/gpu/drm/drm_atomic_state_helper.c
>> index 0f7e5ba555b8..2c9b52ae1b56 100644
>> --- a/drivers/gpu/drm/drm_atomic_state_helper.c
>> +++ b/drivers/gpu/drm/drm_atomic_state_helper.c
>> @@ -569,6 +569,9 @@ EXPORT_SYMBOL(drm_atomic_helper_connector_tv_reset);
>> void __drm_atomic_helper_connector_hdmi_reset(struct drm_connector *connector,
>> struct drm_connector_state *new_state)
>> {
>> + new_state->max_bpc = 8;
>> + new_state->max_requested_bpc = 8;
>> + new_state->hdmi.output_bpc = 8;
>
> Hi,
>
> will this be forcing all drivers using these helpers to default to max bpc = 8?
>
> I believe at least amdgpu would disagree. The defaults were changed in
> the recent years, IIRC to avoid extra modesets during boot-up when
> desktops prefer highest possible bpc for a mode.
>
> The 'max bpc' property itself is a manual workaround for faulty
> hardware that does not correctly indicate the max bpc it can handle. It
> should not default to be a limiting factor.
>
>> new_state->hdmi.broadcast_rgb = DRM_HDMI_BROADCAST_RGB_AUTO;
>> }
>> EXPORT_SYMBOL(__drm_atomic_helper_connector_hdmi_reset);
>> @@ -651,7 +654,8 @@ int drm_atomic_helper_connector_hdmi_check(struct drm_connector *connector,
>> struct drm_connector_state *new_state =
>> drm_atomic_get_new_connector_state(state, connector);
>>
>> - if (old_state->hdmi.broadcast_rgb != new_state->hdmi.broadcast_rgb) {
>> + if (old_state->hdmi.broadcast_rgb != new_state->hdmi.broadcast_rgb ||
>> + old_state->hdmi.output_bpc != new_state->hdmi.output_bpc) {
>> struct drm_crtc *crtc = new_state->crtc;
>> struct drm_crtc_state *crtc_state;
>>
>> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
>> index b45471d540ac..f55f5918411c 100644
>> --- a/drivers/gpu/drm/drm_connector.c
>> +++ b/drivers/gpu/drm/drm_connector.c
>> @@ -459,6 +459,7 @@ EXPORT_SYMBOL(drmm_connector_init);
>> * @funcs: callbacks for this connector
>> * @connector_type: user visible type of the connector
>> * @ddc: optional pointer to the associated ddc adapter
>> + * @max_bpc: Maximum bits per char the HDMI connector supports
>> *
>> * Initialises a preallocated HDMI connector. Connectors can be
>> * subclassed as part of driver connector objects.
>> @@ -475,7 +476,8 @@ int drmm_connector_hdmi_init(struct drm_device *dev,
>> struct drm_connector *connector,
>> const struct drm_connector_funcs *funcs,
>> int connector_type,
>> - struct i2c_adapter *ddc)
>> + struct i2c_adapter *ddc,
>> + unsigned int max_bpc)
>> {
>> int ret;
>>
>> @@ -487,6 +489,15 @@ int drmm_connector_hdmi_init(struct drm_device *dev,
>> if (ret)
>> return ret;
>>
>> + if (max_bpc) {
>> + if (!(max_bpc == 8 || max_bpc == 10 || max_bpc == 12))
>> + return -EINVAL;
>> +
>> + drm_connector_attach_hdr_output_metadata_property(connector);
>> + drm_connector_attach_max_bpc_property(connector, 8, max_bpc);
>> + connector->max_bpc = max_bpc;
>> + }
>> +
>> return 0;
>> }
>> EXPORT_SYMBOL(drmm_connector_hdmi_init);
>> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
>> index fdcf64ab91a9..d0bcb835c857 100644
>> --- a/include/drm/drm_connector.h
>> +++ b/include/drm/drm_connector.h
>> @@ -1056,6 +1056,11 @@ struct drm_connector_state {
>> * Broadcast RGB selection value.
>> */
>> enum drm_hdmi_broadcast_rgb broadcast_rgb;
>> +
>> + /**
>> + * @output_bpc: Bits per character to output.
>
> Is it not bits per channel?

Or component. Or color. Or color channel. ;)

But character I've never heard.

BR,
Jani.

>
>> + */
>> + unsigned int output_bpc;
>> } hdmi;
>> };
>>
>> @@ -1700,6 +1705,11 @@ struct drm_connector {
>> */
>> struct drm_property_blob *path_blob_ptr;
>>
>> + /**
>> + * @max_bpc: Maximum bits per character the connector supports.
>
> channel?
>
>> + */
>> + unsigned int max_bpc;
>> +
>> /**
>> * @max_bpc_property: Default connector property for the max bpc to be
>> * driven out of the connector.
>> @@ -1939,7 +1949,8 @@ int drmm_connector_hdmi_init(struct drm_device *dev,
>> struct drm_connector *connector,
>> const struct drm_connector_funcs *funcs,
>> int connector_type,
>> - struct i2c_adapter *ddc);
>> + struct i2c_adapter *ddc,
>> + unsigned int max_bpc);
>> void drm_connector_attach_edid_property(struct drm_connector *connector);
>> int drm_connector_register(struct drm_connector *connector);
>> void drm_connector_unregister(struct drm_connector *connector);
>>
>
> Thanks,
> pq

--
Jani Nikula, Intel