Re: [PATCH 03/12] drm/edid: Parse the HDMI CEA block and look for 4k modes

Simon Farnsworth
2013-08-14T09:32:51Z

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Minor typo - feel free to ignore:

On Wednesday 14 August 2013 00:17:19 Damien Lespiau wrote:
> HDMI 1.4 adds 4 "4k x 2k" modes in the the CEA vendor specific block.
>
> With this commit, we now parse this block and expose the 4k modes that
> we find there.
>
> v2: Fix the "4096x2160" string (nice catch!), add comments about
> do_hdmi_vsdb_modes() arguments and make it clearer that offset is
> relative to the end of the required fields of the HDMI VSDB
> (Ville Syrjälä)
>
> Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
> Tested-by: Cancan Feng <cancan.feng@intel.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=67030
> ---
> drivers/gpu/drm/drm_edid.c | 124 +++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 109 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 9e9b6ed..0faa08e 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c

<snip>

> @@ -2465,6 +2495,68 @@ do_cea_modes(struct drm_connector *connector, const u8 *db, u8 len)
> return modes;
> }
>
> +/*
> + * do_hdmi_vsdb_modes - Parse the HDMI Vendor Specific data block
> + * @connector: connector corresponding to the HDMI sink
> + * @db: start of the CEA vendor specific block
> + * @len: length of the CEA block payload, ie. one can access up to db[len]
> + *
> + * Parses the HDMI VSDB looking for modes to add to @connector.
> + */
> +static int
> +do_hdmi_vsdb_modes(struct drm_connector *connector, const u8 *db, u8 len)
> +{
> + struct drm_device *dev = connector->dev;
> + int modes = 0, offset = 0, i;
> + u8 vic_len;
> +
> + if (len < 8)
> + goto out;
> +
> + /* no HDMI_Video_Present */
> + if (!(db[8] & (1 << 5)))
> + goto out;
> +
> + /* Latency_Fields_Present */
> + if (db[8] & (1 << 7))
> + offset += 2;
> +
> + /* I_Latency_Fields_Present */
> + if (db[8] & (1 << 6))
> + offset += 2;
> +
> + /* the declared length is not long enough for the 2 first bytes
> + * of additional video format capabilities */
> + offset += 2;
> + if (len < (8 + offset))
> + goto out;
> +
> + vic_len = db[8 + offset] >> 5;
> +
> + for (i = 0; i < vic_len && len >= (9 + offset + i); i++) {
> + struct drm_display_mode *newmode;
> + u8 vic;
> +
> + vic = db[9 + offset + i];
> +
> + vic--; /* VICs start at 1 */
> + if (vic >= ARRAY_SIZE(edid_4k_modes)) {
> + DRM_ERROR("Unknow HDMI VIC: %d\n", vic);
^^^^^^
Missing "n" - should be Unknown
> + continue;
> + }
> +
> + newmode = drm_mode_duplicate(dev, &edid_4k_modes[vic]);
> + if (!newmode)
> + continue;
> +
> + drm_mode_probed_add(connector, newmode);
> + modes++;
> + }
> +
> +out:
> + return modes;
> +}
> +
> static int
> cea_db_payload_len(const u8 *db)
> {
<snip>
--
Simon Farnsworth
Software Engineer
ONELAN Ltd
http://www.onelan.com

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