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

From: Simon Farnsworth <simon.farnsworth@onelan.co.uk>
To: dri-devel@lists.freedesktop.org
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 03/12] drm/edid: Parse the HDMI CEA block and look for 4k modes
Date: Wed, 14 Aug 2013 10:32:51 +0100	[thread overview]
Message-ID: <3743488.ljDhOqH5Y9@f17simon> (raw)
In-Reply-To: <1376435848-14584-4-git-send-email-damien.lespiau@intel.com>

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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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