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From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date: Wed, 14 Feb 2024 10:15:27 +0200
Message-ID: <CAA8EJpo0yeLyCkVvLFX7wUEV4+i+ORbaCB2qxN0izaWLdFqCrA@mail.gmail.com>
Subject: Re: [PATCH] drm/dp: move intel_dp_vsc_sdp_pack() to generic helper
To: Abhinav Kumar <quic_abhinavk@quicinc.com>
Cc: dri-devel@lists.freedesktop.org, 
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, Maxime Ripard <mripard@kernel.org>, 
	Thomas Zimmermann <tzimmermann@suse.de>, David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>, 
	Jani Nikula <jani.nikula@linux.intel.com>, Rodrigo Vivi <rodrigo.vivi@intel.com>, 
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>, 
	Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>, robdclark@gmail.com, 
	freedreno@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, 
	ville.syrjala@linux.intel.com, quic_jesszhan@quicinc.com, 
	linux-kernel@vger.kernel.org, intel-xe@lists.freedesktop.org
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On Wed, 14 Feb 2024 at 01:45, Abhinav Kumar <quic_abhinavk@quicinc.com> wrote:
>
> intel_dp_vsc_sdp_pack() can be re-used by other DRM drivers as well.
> Lets move this to drm_dp_helper to achieve this.
>
> Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>

My preference would be to have packing functions in
drivers/video/hdmi.c, as we already have
hdmi_audio_infoframe_pack_for_dp() there.

> ---
>  drivers/gpu/drm/display/drm_dp_helper.c | 78 +++++++++++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_dp.c | 73 +----------------------
>  include/drm/display/drm_dp_helper.h     |  3 +
>  3 files changed, 84 insertions(+), 70 deletions(-)
>
> diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
> index b1ca3a1100da..066cfbbf7a91 100644
> --- a/drivers/gpu/drm/display/drm_dp_helper.c
> +++ b/drivers/gpu/drm/display/drm_dp_helper.c
> @@ -2916,6 +2916,84 @@ void drm_dp_vsc_sdp_log(const char *level, struct device *dev,
>  }
>  EXPORT_SYMBOL(drm_dp_vsc_sdp_log);
>
> +/**
> + * drm_dp_vsc_sdp_pack() - pack a given vsc sdp into generic dp_sdp
> + * @vsc: vsc sdp initialized according to its purpose as defined in
> + *       table 2-118 - table 2-120 in DP 1.4a specification
> + * @sdp: valid handle to the generic dp_sdp which will be packed
> + * @size: valid size of the passed sdp handle
> + *
> + * Returns length of sdp on success and error code on failure
> + */
> +ssize_t drm_dp_vsc_sdp_pack(const struct drm_dp_vsc_sdp *vsc,
> +                           struct dp_sdp *sdp, size_t size)

I know that you are just moving the function. Maybe there can be
patch#2, which drops the size argument? The struct dp_sdp already has
a defined size. The i915 driver just passes sizeof(sdp), which is more
or less useless.

> +{
> +       size_t length = sizeof(struct dp_sdp);
> +
> +       if (size < length)
> +               return -ENOSPC;
> +
> +       memset(sdp, 0, size);
> +
> +       /*
> +        * Prepare VSC Header for SU as per DP 1.4a spec, Table 2-119
> +        * VSC SDP Header Bytes
> +        */
> +       sdp->sdp_header.HB0 = 0; /* Secondary-Data Packet ID = 0 */
> +       sdp->sdp_header.HB1 = vsc->sdp_type; /* Secondary-data Packet Type */
> +       sdp->sdp_header.HB2 = vsc->revision; /* Revision Number */
> +       sdp->sdp_header.HB3 = vsc->length; /* Number of Valid Data Bytes */
> +
> +       if (vsc->revision == 0x6) {
> +               sdp->db[0] = 1;
> +               sdp->db[3] = 1;
> +       }
> +
> +       /*
> +        * Revision 0x5 and revision 0x7 supports Pixel Encoding/Colorimetry
> +        * Format as per DP 1.4a spec and DP 2.0 respectively.
> +        */
> +       if (!(vsc->revision == 0x5 || vsc->revision == 0x7))
> +               goto out;
> +
> +       /* VSC SDP Payload for DB16 through DB18 */
> +       /* Pixel Encoding and Colorimetry Formats  */
> +       sdp->db[16] = (vsc->pixelformat & 0xf) << 4; /* DB16[7:4] */
> +       sdp->db[16] |= vsc->colorimetry & 0xf; /* DB16[3:0] */
> +
> +       switch (vsc->bpc) {
> +       case 6:
> +               /* 6bpc: 0x0 */
> +               break;
> +       case 8:
> +               sdp->db[17] = 0x1; /* DB17[3:0] */
> +               break;
> +       case 10:
> +               sdp->db[17] = 0x2;
> +               break;
> +       case 12:
> +               sdp->db[17] = 0x3;
> +               break;
> +       case 16:
> +               sdp->db[17] = 0x4;
> +               break;
> +       default:
> +               WARN(1, "Missing case %d\n", vsc->bpc);
> +               return -EINVAL;
> +       }
> +
> +       /* Dynamic Range and Component Bit Depth */
> +       if (vsc->dynamic_range == DP_DYNAMIC_RANGE_CTA)
> +               sdp->db[17] |= 0x80;  /* DB17[7] */
> +
> +       /* Content Type */
> +       sdp->db[18] = vsc->content_type & 0x7;
> +
> +out:
> +       return length;
> +}
> +EXPORT_SYMBOL(drm_dp_vsc_sdp_pack);
> +
>  /**
>   * drm_dp_get_pcon_max_frl_bw() - maximum frl supported by PCON
>   * @dpcd: DisplayPort configuration data
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index f5ef95da5534..e94db51aeeb7 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -4110,73 +4110,6 @@ intel_dp_needs_vsc_sdp(const struct intel_crtc_state *crtc_state,
>         return false;
>  }
>
> -static ssize_t intel_dp_vsc_sdp_pack(const struct drm_dp_vsc_sdp *vsc,
> -                                    struct dp_sdp *sdp, size_t size)
> -{
> -       size_t length = sizeof(struct dp_sdp);
> -
> -       if (size < length)
> -               return -ENOSPC;
> -
> -       memset(sdp, 0, size);
> -
> -       /*
> -        * Prepare VSC Header for SU as per DP 1.4a spec, Table 2-119
> -        * VSC SDP Header Bytes
> -        */
> -       sdp->sdp_header.HB0 = 0; /* Secondary-Data Packet ID = 0 */
> -       sdp->sdp_header.HB1 = vsc->sdp_type; /* Secondary-data Packet Type */
> -       sdp->sdp_header.HB2 = vsc->revision; /* Revision Number */
> -       sdp->sdp_header.HB3 = vsc->length; /* Number of Valid Data Bytes */
> -
> -       if (vsc->revision == 0x6) {
> -               sdp->db[0] = 1;
> -               sdp->db[3] = 1;
> -       }
> -
> -       /*
> -        * Revision 0x5 and revision 0x7 supports Pixel Encoding/Colorimetry
> -        * Format as per DP 1.4a spec and DP 2.0 respectively.
> -        */
> -       if (!(vsc->revision == 0x5 || vsc->revision == 0x7))
> -               goto out;
> -
> -       /* VSC SDP Payload for DB16 through DB18 */
> -       /* Pixel Encoding and Colorimetry Formats  */
> -       sdp->db[16] = (vsc->pixelformat & 0xf) << 4; /* DB16[7:4] */
> -       sdp->db[16] |= vsc->colorimetry & 0xf; /* DB16[3:0] */
> -
> -       switch (vsc->bpc) {
> -       case 6:
> -               /* 6bpc: 0x0 */
> -               break;
> -       case 8:
> -               sdp->db[17] = 0x1; /* DB17[3:0] */
> -               break;
> -       case 10:
> -               sdp->db[17] = 0x2;
> -               break;
> -       case 12:
> -               sdp->db[17] = 0x3;
> -               break;
> -       case 16:
> -               sdp->db[17] = 0x4;
> -               break;
> -       default:
> -               MISSING_CASE(vsc->bpc);
> -               break;
> -       }
> -       /* Dynamic Range and Component Bit Depth */
> -       if (vsc->dynamic_range == DP_DYNAMIC_RANGE_CTA)
> -               sdp->db[17] |= 0x80;  /* DB17[7] */
> -
> -       /* Content Type */
> -       sdp->db[18] = vsc->content_type & 0x7;
> -
> -out:
> -       return length;
> -}
> -
>  static ssize_t
>  intel_dp_hdr_metadata_infoframe_sdp_pack(struct drm_i915_private *i915,
>                                          const struct hdmi_drm_infoframe *drm_infoframe,
> @@ -4269,8 +4202,8 @@ static void intel_write_dp_sdp(struct intel_encoder *encoder,
>
>         switch (type) {
>         case DP_SDP_VSC:
> -               len = intel_dp_vsc_sdp_pack(&crtc_state->infoframes.vsc, &sdp,
> -                                           sizeof(sdp));
> +               len = drm_dp_vsc_sdp_pack(&crtc_state->infoframes.vsc, &sdp,
> +                                         sizeof(sdp));
>                 break;
>         case HDMI_PACKET_TYPE_GAMUT_METADATA:
>                 len = intel_dp_hdr_metadata_infoframe_sdp_pack(dev_priv,
> @@ -4297,7 +4230,7 @@ void intel_write_dp_vsc_sdp(struct intel_encoder *encoder,
>         struct dp_sdp sdp = {};
>         ssize_t len;
>
> -       len = intel_dp_vsc_sdp_pack(vsc, &sdp, sizeof(sdp));
> +       len = drm_dp_vsc_sdp_pack(vsc, &sdp, sizeof(sdp));
>
>         if (drm_WARN_ON(&dev_priv->drm, len < 0))
>                 return;
> diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
> index 863b2e7add29..f8db34a2f7a5 100644
> --- a/include/drm/display/drm_dp_helper.h
> +++ b/include/drm/display/drm_dp_helper.h
> @@ -813,4 +813,7 @@ int drm_dp_bw_overhead(int lane_count, int hactive,
>                        int bpp_x16, unsigned long flags);
>  int drm_dp_bw_channel_coding_efficiency(bool is_uhbr);
>
> +ssize_t drm_dp_vsc_sdp_pack(const struct drm_dp_vsc_sdp *vsc,
> +                           struct dp_sdp *sdp, size_t size);
> +
>  #endif /* _DRM_DP_HELPER_H_ */
> --
> 2.34.1
>


-- 
With best wishes
Dmitry