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drm/edid: add helper for HDMI VSDB audio latency field length

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Add a helper for skipping the HDMI VSDB audio latency fields.

There's a functional change for HDMI VSDB blocks that do not respect the
spec: "I_Latency_Fields_Present shall be zero if Latency_Fields_Present
is zero". We assume this to hold when skipping the latency fields, and
ignore non-zero I_Latency_Fields_Present if Latency_Fields_Present is
zero.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/da4293203ef2ddeb0bf66a2bfdbc129ab609c543.1672826282.git.jani.nikula@intel.com
This commit is contained in:
Jani Nikula 2023-01-04 12:05:25 +02:00
parent 1ee3e217f9
commit cba83c1fc3
1 changed files with 11 additions and 7 deletions
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18
drivers/gpu/drm/drm_edid.c
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@ -4695,6 +4695,16 @@ static bool hdmi_vsdb_i_latency_present(const u8 *db)
return hdmi_vsdb_latency_present(db) && db[8] & BIT(6);
}
static int hdmi_vsdb_latency_length(const u8 *db)
{
if (hdmi_vsdb_i_latency_present(db))
return 4;
else if (hdmi_vsdb_latency_present(db))
return 2;
else
return 0;
}
/*
* do_hdmi_vsdb_modes - Parse the HDMI Vendor Specific data block
* @connector: connector corresponding to the HDMI sink
@ -4720,13 +4730,7 @@ do_hdmi_vsdb_modes(struct drm_connector *connector, const u8 *db, u8 len)
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;
offset += hdmi_vsdb_latency_length(db);
/* the declared length is not long enough for the 2 first bytes
* of additional video format capabilities */