Re: [PATCH v2 2/2] drm: parse hf-vsdb

Jose Abreu
2016-12-20T14:35:57Z

Hi Shashank,

On 20-12-2016 13:47, Shashank Sharma wrote:
> HDMI 2.0 / CEA-861-F specs define a new CEA extension data block,
> called hdmi-forum vendor specific data block (HF-VSDB). This block
> contains information about sink's support for HDMI 2.0 compliant
> features. These features are:
> - Deep color YUV 420 support and BPC
> - 3D flags for
> - OSD Displarity
> - Dual view signaling
> - independent view signaling
> - SCDC support
> - Max TMDS char rate
> - Scrambling support
>
> This patch adds a parser function for this block, and add flags to
> indicate support for new features, in drm_display_info structure
>
> V2:
> - Addressed review comments from Thierry
> - remove len > 31 check
> - remove version check
> - fix duplicate values for macros of 36 and 30-bit depths
> - Added a sub-class for HDMI related information within drm_display_info
> (Thierry, Daniel) and populated it with HF-VSDB specific info.
>
> Cc: Thierry Reding <treding@nvidia.com>
> Cc: Daniel Vetter <daniel.vetter@intel.com>
> Cc: Jose Abreu <joabreu@synopsys.com>
> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
> ---
> drivers/gpu/drm/drm_edid.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++
> include/drm/drm_edid.h | 5 ++++
> include/linux/hdmi.h | 1 +
> 3 files changed, 76 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index b552197..59e04fb 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -3224,6 +3224,23 @@ static int add_3d_struct_modes(struct drm_connector *connector, u16 structure,
> return 0;
> }
>
> +static bool cea_db_is_hf_vsdb(const u8 *db)
> +{
> + u8 len;
> + int hfvsdb_id;
> +
> + if (cea_db_tag(db) != VENDOR_BLOCK)
> + return false;
> +
> + len = cea_db_payload_len(db);
> + if (len < 7)
> + return false;
> +
> + hfvsdb_id = db[1] | (db[2] << 8) | (db[3] << 16);
> +
> + return hfvsdb_id == HDMI_IEEE_OUI_HFVSDB;
> +}
> +
> static bool cea_db_is_hdmi_vsdb(const u8 *db)
> {
> int hdmi_id;
> @@ -3768,6 +3785,57 @@ bool drm_rgb_quant_range_selectable(struct edid *edid)
> }
> EXPORT_SYMBOL(drm_rgb_quant_range_selectable);
>
> +static void drm_parse_yuv420_deep_color_info(struct drm_connector *connector,
> + const u8 *db)
> +{
> + struct drm_hdmi_info *info = &connector->display_info.hdmi_info;
> +
> + if (db[7] & DRM_EDID_YUV420_DC_48)
> + info->edid_yuv420_dc_modes |= DRM_EDID_YUV420_DC_48;
> + if (db[7] & DRM_EDID_YUV420_DC_36)
> + info->edid_yuv420_dc_modes |= DRM_EDID_YUV420_DC_36;
> + if (db[7] & DRM_EDID_YUV420_DC_30)
> + info->edid_yuv420_dc_modes |= DRM_EDID_YUV420_DC_30;
> +
> + if (!info->edid_yuv420_dc_modes) {
> + DRM_DEBUG("%s: No YUV 420 deep color support in sink.\n",
> + connector->name);
> + return;
> + }
> +}
> +
> +static void
> +drm_parse_hf_vsdb(struct drm_connector *connector, const u8 *db)
> +{
> + struct drm_display_info *info = &connector->display_info;
> + struct drm_hdmi_info *hdmi_info = &info->hdmi_info;
> +
> + if (db[5]) {
> + /*
> + * If the sink supplies max tmds char rate in db,
> + * the actual max tmds rate = db[5] * 5Mhz.
> + */
> + info->max_tmds_clock = db[5] * 5000;
> + DRM_DEBUG_KMS("HF-VSDB: max TMDS clock %d kHz\n",
> + info->max_tmds_clock);
> + }
> +
> + if (db[6] & DRM_HFVSDB_SCDC_SUPPORT)
> + hdmi_info->scdc_supported = true;
> + if (db[6] & DRM_HFVSDB_SCDC_RR_CAP)
> + hdmi_info->scdc_rr_cap = true;
> + if (db[6] & DRM_HFVSDB_SCRAMBLING)
> + hdmi_info->scrambling = true;

According to spec you should also check if scdc is supported in
order to support scrambling.

> + if (db[6] & DRM_HFVSDB_INDEPENDENT_VIEW)
> + hdmi_info->independent_view_3d = true;
> + if (db[6] & DRM_HFVSDB_DUAL_VIEW)
> + hdmi_info->dual_view_3d = true;
> + if (db[6] & DRM_HFVSDB_3D_OSD)
> + hdmi_info->osd_disparity_3d = true;
> +
> + drm_parse_yuv420_deep_color_info(connector, db);
> +}
> +
> static void drm_parse_hdmi_deep_color_info(struct drm_connector *connector,
> const u8 *hdmi)
> {
> @@ -3882,6 +3950,8 @@ static void drm_parse_cea_ext(struct drm_connector *connector,
>
> if (cea_db_is_hdmi_vsdb(db))
> drm_parse_hdmi_vsdb_video(connector, db);
> + if (cea_db_is_hf_vsdb(db))
> + drm_parse_hf_vsdb(connector, db);
> }
> }
>
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index 38eabf6..df606e3 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -212,6 +212,11 @@ struct detailed_timing {
> #define DRM_EDID_HDMI_DC_30 (1 << 4)
> #define DRM_EDID_HDMI_DC_Y444 (1 << 3)
>
> +/* YUV 420 deep color modes */
> +#define DRM_EDID_YUV420_DC_48 (1 << 6)
> +#define DRM_EDID_YUV420_DC_36 (1 << 5)
> +#define DRM_EDID_YUV420_DC_30 (1 << 4)

Hmm, I think this is wrong. According to spec DC 48 is at
position 2, DC 36 at position 1 and DC 30 at position 0.

> +
> /* ELD Header Block */
> #define DRM_ELD_HEADER_BLOCK_SIZE 4
>
> diff --git a/include/linux/hdmi.h b/include/linux/hdmi.h
> index edbb4fc..2d4e9ef 100644
> --- a/include/linux/hdmi.h
> +++ b/include/linux/hdmi.h
> @@ -35,6 +35,7 @@ enum hdmi_infoframe_type {
> };
>
> #define HDMI_IEEE_OUI 0x000c03
> +#define HDMI_IEEE_OUI_HFVSDB 0xC45DD8

Lower case, because HDMI_IEEE_OUI is also lower case.

> #define HDMI_INFOFRAME_HEADER_SIZE 4
> #define HDMI_AVI_INFOFRAME_SIZE 13
> #define HDMI_SPD_INFOFRAME_SIZE 25

Best regards,
Jose Miguel Abreu