Date:   Tue, 15 Aug 2023 12:20:26 +0100
From:   Dave Stevenson <dave.stevenson@...pberrypi.com>
To:     Maxime Ripard <mripard@...nel.org>
Cc:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, Emma Anholt <emma@...olt.net>,
        Hans Verkuil <hverkuil@...all.nl>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH RFC 10/13] drm/connector: hdmi: Add Infoframes generation

Hi Maxime

On Mon, 14 Aug 2023 at 14:56, Maxime Ripard <mripard@...nel.org> wrote:
>
> Infoframes in KMS is usually handled by a bunch of low-level helpers
> that require quite some boilerplate for drivers. This leads to
> discrepancies with how drivers generate them, and which are actually
> sent.
>
> Now that we have everything needed to generate them in the HDMI
> connector state, we can generate them in our common logic so that
> drivers can simply reuse what we precomputed.
>
> Signed-off-by: Maxime Ripard <mripard@...nel.org>
> ---
>  drivers/gpu/drm/drm_hdmi_connector.c | 287 +++++++++++++++++++++++++++++++++++
>  include/drm/drm_connector.h          | 100 ++++++++++++
>  2 files changed, 387 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_hdmi_connector.c b/drivers/gpu/drm/drm_hdmi_connector.c
> index 22c49906dfb5..46cafb17def7 100644
> --- a/drivers/gpu/drm/drm_hdmi_connector.c
> +++ b/drivers/gpu/drm/drm_hdmi_connector.c
> @@ -5,8 +5,10 @@
>  #include <drm/drm_connector.h>
>  #include <drm/drm_crtc.h>
>  #include <drm/drm_edid.h>
> +#include <drm/drm_managed.h>
>  #include <drm/drm_mode.h>
>  #include <drm/drm_print.h>
> +#include <drm/display/drm_hdmi_helper.h>
>
>  #include <linux/export.h>
>
> @@ -499,6 +501,131 @@ drm_hdmi_connector_compute_config(const struct drm_hdmi_connector *hdmi_connecto
>         return -EINVAL;
>  }
>
> +static int
> +drm_hdmi_connector_generate_avi_infoframe(const struct drm_hdmi_connector *hdmi_connector,
> +                                         struct drm_hdmi_connector_state *hdmi_state)
> +{
> +       const struct drm_connector *connector = &hdmi_connector->base;
> +       const struct drm_connector_state *state = &hdmi_state->base;
> +       const struct drm_display_mode *mode =
> +               connector_state_get_adjusted_mode(state);
> +       struct hdmi_avi_infoframe *frame = &hdmi_state->infoframes.avi;
> +       bool is_lim_range =
> +               drm_atomic_helper_hdmi_connector_is_full_range(hdmi_connector,
> +                                                              hdmi_state);
> +       enum hdmi_quantization_range rgb_quant_range =
> +               is_lim_range ? HDMI_QUANTIZATION_RANGE_FULL : HDMI_QUANTIZATION_RANGE_LIMITED;
> +       int ret;
> +
> +       ret = drm_hdmi_avi_infoframe_from_display_mode(frame, connector, mode);
> +       if (ret)
> +               return ret;
> +
> +       frame->colorspace = hdmi_state->output_format;
> +
> +       drm_hdmi_avi_infoframe_quant_range(frame, connector, mode, rgb_quant_range);
> +       drm_hdmi_avi_infoframe_colorimetry(frame, state);
> +       drm_hdmi_avi_infoframe_bars(frame, state);
> +
> +       return 0;
> +}
> +
> +static int
> +drm_hdmi_connector_generate_spd_infoframe(const struct drm_hdmi_connector *hdmi_connector,
> +                                         struct drm_hdmi_connector_state *hdmi_state)
> +{
> +       struct hdmi_spd_infoframe *frame = &hdmi_state->infoframes.spd;
> +       int ret;
> +
> +       ret = hdmi_spd_infoframe_init(frame,
> +                                     hdmi_connector->vendor,
> +                                     hdmi_connector->product);
> +       if (ret)
> +               return ret;
> +
> +       frame->sdi = HDMI_SPD_SDI_PC;
> +
> +       return 0;
> +}
> +
> +static int
> +drm_hdmi_connector_generate_hdr_infoframe(const struct drm_hdmi_connector *hdmi_connector,
> +                                         struct drm_hdmi_connector_state *hdmi_state)
> +{
> +       const struct drm_connector_state *state = &hdmi_state->base;
> +       struct hdmi_drm_infoframe *frame = &hdmi_state->infoframes.drm;
> +       int ret;
> +
> +       if (hdmi_connector->max_bpc < 10)
> +               return 0;
> +
> +       if (!state->hdr_output_metadata)
> +               return 0;

Minor issue here I think.

If bpc < 10 or hdr_output_metadata isn't defined then the infoframe
will be left at all 0's due to the state's kzalloc. However we will
still call update_infoframe and therefore write_infoframe asking for
the infoframe to be sent, but frame->any.type = 0. It is true that
frame type 0 isn't defined, but what is the driver expected to make of
that?

If frame->any.type is initialised appropriately (or type is passed
directly), then a length of 0 could be reasonably used to signal that
the infoframe should not be sent. Otherwise I don't think we have a
path which can stop sending the HDR infoframe if it has ever been
sent.

On vc4 I think it's also going to trip up as it has a buffer slot per
type, and slot 0 is used for the GCP.

Thanks
  Dave

> +
> +       ret = drm_hdmi_infoframe_set_hdr_metadata(frame, state);
> +       if (ret)
> +               return ret;
> +
> +       return 0;
> +}
> +
> +static int
> +drm_hdmi_connector_generate_vendor_infoframe(const struct drm_hdmi_connector *hdmi_connector,
> +                                            struct drm_hdmi_connector_state *hdmi_state)
> +{
> +       const struct drm_connector *connector = &hdmi_connector->base;
> +       const struct drm_connector_state *state = &hdmi_state->base;
> +       const struct drm_display_mode *mode =
> +               connector_state_get_adjusted_mode(state);
> +       struct hdmi_vendor_infoframe *frame = &hdmi_state->infoframes.vendor;
> +       int ret;
> +
> +       ret = drm_hdmi_vendor_infoframe_from_display_mode(frame, connector, mode);
> +       if (ret == -EINVAL)
> +               return 0;
> +       else
> +               return ret;
> +
> +       return 0;
> +}
> +
> +static int
> +drm_hdmi_connector_generate_infoframes(const struct drm_hdmi_connector *hdmi_connector,
> +                                      struct drm_hdmi_connector_state *hdmi_state)
> +{
> +       const struct drm_connector *connector = &hdmi_connector->base;
> +       const struct drm_display_info *info = &connector->display_info;
> +       int ret;
> +
> +       if (!info->is_hdmi)
> +               return 0;
> +
> +       if (!info->has_hdmi_infoframe)
> +               return 0;
> +
> +       ret = drm_hdmi_connector_generate_avi_infoframe(hdmi_connector, hdmi_state);
> +       if (ret)
> +               return ret;
> +
> +       ret = drm_hdmi_connector_generate_spd_infoframe(hdmi_connector, hdmi_state);
> +       if (ret)
> +               return ret;
> +
> +       /*
> +        * Audio Infoframes will be generated by ALSA.
> +        */
> +
> +       ret = drm_hdmi_connector_generate_hdr_infoframe(hdmi_connector, hdmi_state);
> +       if (ret)
> +               return ret;
> +
> +       ret = drm_hdmi_connector_generate_vendor_infoframe(hdmi_connector, hdmi_state);
> +       if (ret)
> +               return ret;
> +
> +       return 0;
> +}
> +
>  /**
>   * drm_atomic_helper_hdmi_connector_atomic_check() - Helper to check HDMI connector atomic state
>   * @connector: the parent connector this state refers to
> @@ -536,6 +663,10 @@ int drm_atomic_helper_hdmi_connector_atomic_check(struct drm_connector *connecto
>         if (ret)
>                 return ret;
>
> +       ret = drm_hdmi_connector_generate_infoframes(hdmi_connector, new_hdmi_state);
> +       if (ret)
> +               return ret;
> +
>         if (old_hdmi_state->broadcast_rgb != new_hdmi_state->broadcast_rgb ||
>             old_hdmi_state->output_format != new_hdmi_state->output_format ||
>             old_hdmi_state->output_bpc != new_hdmi_state->output_bpc) {
> @@ -553,6 +684,152 @@ int drm_atomic_helper_hdmi_connector_atomic_check(struct drm_connector *connecto
>  }
>  EXPORT_SYMBOL(drm_atomic_helper_hdmi_connector_atomic_check);
>
> +#define HDMI_MAX_INFOFRAME_SIZE                29
> +
> +static int write_infoframe(struct drm_hdmi_connector *hdmi_connector,
> +                          union hdmi_infoframe *frame)
> +{
> +       const struct drm_hdmi_connector_funcs *funcs = hdmi_connector->funcs;
> +       u8 buffer[HDMI_MAX_INFOFRAME_SIZE];
> +       int len;
> +
> +       if (!funcs || !funcs->write_infoframe)
> +               return -ENOSYS;
> +
> +       len = hdmi_infoframe_pack(frame, buffer, sizeof(buffer));
> +       if (len < 0)
> +               return len;
> +
> +       return funcs->write_infoframe(hdmi_connector, frame->any.type, buffer, len);
> +}
> +
> +static int update_infoframe(struct drm_hdmi_connector *hdmi_connector,
> +                           union hdmi_infoframe *frame)
> +{
> +       int ret;
> +
> +       ret = write_infoframe(hdmi_connector, frame);
> +       if (ret)
> +               return ret;
> +
> +       switch (frame->any.type) {
> +       case HDMI_INFOFRAME_TYPE_AVI:
> +               memcpy(&hdmi_connector->infoframes.avi, &frame->avi,
> +                      sizeof(hdmi_connector->infoframes.avi));
> +               break;
> +       case HDMI_INFOFRAME_TYPE_DRM:
> +               memcpy(&hdmi_connector->infoframes.drm, &frame->drm,
> +                      sizeof(hdmi_connector->infoframes.drm));
> +               break;
> +       case HDMI_INFOFRAME_TYPE_SPD:
> +               memcpy(&hdmi_connector->infoframes.spd, &frame->spd,
> +                      sizeof(hdmi_connector->infoframes.spd));
> +               break;
> +       case HDMI_INFOFRAME_TYPE_VENDOR:
> +               memcpy(&hdmi_connector->infoframes.vendor, &frame->vendor,
> +                      sizeof(hdmi_connector->infoframes.vendor));
> +               break;
> +       default:
> +               return -EINVAL;
> +       }
> +
> +       return 0;
> +}
> +
> +#define UPDATE_INFOFRAME(c, i)                                 \
> +       update_infoframe(c, (union hdmi_infoframe *)&(c)->infoframes.i)
> +
> +/**
> + * drm_atomic_helper_hdmi_connector_update_infoframes - Update the Infoframes
> + * @hdmi_connector: A pointer to the HDMI connector
> + * @hdmi_state: The HDMI connector state to generate the infoframe from
> + *
> + * This function is meant for HDMI connector drivers to write their
> + * infoframes. It will typically be used in a
> + * @drm_connector_helper_funcs.atomic_enable implementation.
> + *
> + * Returns:
> + * Zero on success, error code on failure.
> + */
> +int drm_atomic_helper_hdmi_connector_update_infoframes(struct drm_hdmi_connector *hdmi_connector,
> +                                                      struct drm_hdmi_connector_state *hdmi_state)
> +{
> +       struct drm_connector *connector = &hdmi_connector->base;
> +       struct drm_display_info *info = &connector->display_info;
> +       int ret;
> +
> +       if (!info->is_hdmi)
> +               return 0;
> +
> +       if (!info->has_hdmi_infoframe)
> +               return 0;
> +
> +       mutex_lock(&hdmi_connector->infoframes.lock);
> +
> +       ret = UPDATE_INFOFRAME(hdmi_connector, avi);
> +       if (ret)
> +               goto out;
> +
> +       ret = UPDATE_INFOFRAME(hdmi_connector, audio);
> +       if (ret)
> +               goto out;
> +
> +       ret = UPDATE_INFOFRAME(hdmi_connector, drm);
> +       if (ret)
> +               goto out;
> +
> +       ret = UPDATE_INFOFRAME(hdmi_connector, spd);
> +       if (ret)
> +               goto out;
> +
> +       ret = UPDATE_INFOFRAME(hdmi_connector, vendor);
> +       if (ret)
> +               goto out;
> +
> +out:
> +       mutex_unlock(&hdmi_connector->infoframes.lock);
> +       return ret;
> +}
> +EXPORT_SYMBOL(drm_atomic_helper_hdmi_connector_update_infoframes);
> +
> +#undef UPDATE_INFOFRAME
> +
> +/**
> + * drm_atomic_helper_hdmi_connector_update_audio_infoframe - Update the Audio Infoframe
> + * @hdmi_connector: A pointer to the HDMI connector
> + * @frame: A pointer to the audio infoframe to write
> + *
> + * This function is meant for HDMI connector drivers to update their
> + * audio infoframe. It will typically be used in one of the ALSA hooks
> + * (most likely prepare).
> + *
> + * Returns:
> + * Zero on success, error code on failure.
> + */
> +int
> +drm_atomic_helper_hdmi_connector_update_audio_infoframe(struct drm_hdmi_connector *hdmi_connector,
> +                                                       struct hdmi_audio_infoframe *frame)
> +{
> +       struct drm_connector *connector = &hdmi_connector->base;
> +       struct drm_display_info *info = &connector->display_info;
> +       int ret;
> +
> +       if (!info->is_hdmi)
> +               return 0;
> +
> +       if (!info->has_hdmi_infoframe)
> +               return 0;
> +
> +       mutex_lock(&hdmi_connector->infoframes.lock);
> +
> +       ret = update_infoframe(hdmi_connector, (union hdmi_infoframe *)frame);
> +
> +       mutex_unlock(&hdmi_connector->infoframes.lock);
> +
> +       return ret;
> +}
> +EXPORT_SYMBOL(drm_atomic_helper_hdmi_connector_update_audio_infoframe);
> +
>  /**
>   * drm_atomic_helper_hdmi_connector_is_full_range() - Checks whether a state uses Full-Range RGB
>   * @hdmi_connector: the HDMI connector this state refers to
> @@ -634,6 +911,8 @@ EXPORT_SYMBOL(drm_atomic_helper_hdmi_connector_print_state);
>   * drmm_hdmi_connector_init - Init a preallocated HDMI connector
>   * @dev: DRM device
>   * @hdmi_connector: A pointer to the HDMI connector to init
> + * @vendor: HDMI Controller Vendor name
> + * @product: HDMI Controller Product name
>   * @funcs: callbacks for this connector
>   * @connector_type: user visible type of the connector
>   * @ddc: optional pointer to the associated ddc adapter
> @@ -652,6 +931,7 @@ EXPORT_SYMBOL(drm_atomic_helper_hdmi_connector_print_state);
>   */
>  int drmm_hdmi_connector_init(struct drm_device *dev,
>                              struct drm_hdmi_connector *hdmi_connector,
> +                            const char *vendor, const char *product,
>                              const struct drm_connector_funcs *funcs,
>                              const struct drm_hdmi_connector_funcs *hdmi_funcs,
>                              int connector_type,
> @@ -670,6 +950,13 @@ int drmm_hdmi_connector_init(struct drm_device *dev,
>         if (ret)
>                 return ret;
>
> +       strscpy(hdmi_connector->vendor, vendor, sizeof(hdmi_connector->vendor));
> +       strscpy(hdmi_connector->product, product, sizeof(hdmi_connector->product));
> +
> +       ret = drmm_mutex_init(dev, &hdmi_connector->infoframes.lock);
> +       if (ret)
> +               return ret;
> +
>         prop = hdmi_connector->broadcast_rgb_property;
>         if (!prop) {
>                 prop = drm_property_create_enum(dev, DRM_MODE_PROP_ENUM,
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 6e25a16420e4..21da6f428101 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -2096,6 +2096,32 @@ struct drm_hdmi_connector_state {
>          * selection value.
>          */
>         enum drm_hdmi_broadcast_rgb broadcast_rgb;
> +
> +       /**
> +        * @infoframes: HDMI Infoframes matching that state
> +        */
> +       struct {
> +               /**
> +                * @avi: AVI Infoframes structure matching our state.
> +                */
> +               struct hdmi_avi_infoframe avi;
> +
> +               /**
> +                * @drm: DRM Infoframes structure matching our state.
> +                */
> +               struct hdmi_drm_infoframe drm;
> +
> +               /**
> +                * @spd: SPD Infoframes structure matching our state.
> +                */
> +               struct hdmi_spd_infoframe spd;
> +
> +               /**
> +                * @vendor: Vendor Infoframes structure matching our
> +                * state.
> +                */
> +               struct hdmi_vendor_infoframe vendor;
> +       } infoframes;
>  };
>
>  #define connector_state_to_hdmi_connector_state(state) \
> @@ -2127,6 +2153,11 @@ int drm_atomic_helper_hdmi_connector_atomic_check(struct drm_connector *connecto
>  void drm_atomic_helper_hdmi_connector_print_state(struct drm_printer *p,
>                                                   const struct drm_connector_state *state);
>
> +int drm_atomic_helper_hdmi_connector_update_infoframes(struct drm_hdmi_connector *hdmi_connector,
> +                                                      struct drm_hdmi_connector_state *hdmi_state);
> +int drm_atomic_helper_hdmi_connector_update_audio_infoframe(struct drm_hdmi_connector *hdmi_connector,
> +                                                           struct hdmi_audio_infoframe *frame);
> +
>  bool
>  drm_atomic_helper_hdmi_connector_is_full_range(const struct drm_hdmi_connector *hdmi_connector,
>                                                const struct drm_hdmi_connector_state *hdmi_state);
> @@ -2153,6 +2184,23 @@ struct drm_hdmi_connector_funcs {
>         (*tmds_char_rate_valid)(const struct drm_hdmi_connector *connector,
>                                 const struct drm_display_mode *mode,
>                                 unsigned long long tmds_rate);
> +
> +       /**
> +        * @write_infoframe:
> +        *
> +        * This callback is invoked through
> +        * @drm_atomic_helper_hdmi_connector_update_infoframes during a
> +        * commit to program the infoframes into the hardware. It will
> +        * be called multiple times, once for every infoframe type.
> +        *
> +        * The @write_infoframe callback is mandatory.
> +        *
> +        * Returns:
> +        * 0 on success, a negative error code otherwise
> +        */
> +       int (*write_infoframe)(struct drm_hdmi_connector *connector,
> +                              enum hdmi_infoframe_type type,
> +                              const u8 *buffer, size_t len);
>  };
>
>  struct drm_hdmi_connector {
> @@ -2161,6 +2209,16 @@ struct drm_hdmi_connector {
>          */
>         struct drm_connector base;
>
> +       /**
> +        * @vendor: HDMI Controller Vendor Name
> +        */
> +       char vendor[8];
> +
> +       /**
> +        * @product: HDMI Controller Product Name
> +        */
> +       char product[16];
> +
>         /**
>          * @funcs: HDMI connector Control Functions
>          */
> @@ -2176,6 +2234,47 @@ struct drm_hdmi_connector {
>          * Broadcast RGB selection to output with.
>          */
>         struct drm_property *broadcast_rgb_property;
> +
> +       /**
> +        * @infoframes: Current Infoframes output by the connector
> +        */
> +       struct {
> +               /**
> +                * @lock: Mutex protecting against concurrent access to
> +                * the infoframes, most notably between KMS and ALSA.
> +                */
> +               struct mutex lock;
> +
> +               /**
> +                * @audio: Current Audio Infoframes structure. Protected
> +                * by @lock.
> +                */
> +               struct hdmi_audio_infoframe audio;
> +
> +               /**
> +                * @avi: Current AVI Infoframes structure. Protected by
> +                * @lock.
> +                */
> +               struct hdmi_avi_infoframe avi;
> +
> +               /**
> +                * @drm: Current DRM Infoframes structure. Protected by
> +                * @lock.
> +                */
> +               struct hdmi_drm_infoframe drm;
> +
> +               /**
> +                * @spd: Current SPD Infoframes structure. Protected by
> +                * @lock.
> +                */
> +               struct hdmi_spd_infoframe spd;
> +
> +               /**
> +                * @vendor: Current Vendor Infoframes structure.
> +                * Protected by @lock.
> +                */
> +               struct hdmi_vendor_infoframe vendor;
> +       } infoframes;
>  };
>
>  #define connector_to_hdmi_connector(connector) \
> @@ -2188,6 +2287,7 @@ drm_hdmi_connector_compute_mode_clock(const struct drm_display_mode *mode,
>
>  int drmm_hdmi_connector_init(struct drm_device *dev,
>                              struct drm_hdmi_connector *hdmi_connector,
> +                            const char *vendor, const char *product,
>                              const struct drm_connector_funcs *funcs,
>                              const struct drm_hdmi_connector_funcs *hdmi_funcs,
>                              int connector_type,
>
> --
> 2.41.0
>

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