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drm/edid: Fix up clock for CEA/HDMI modes specified via detailed timings

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EDID detailed timings have a resolution of 10kHz for the pixel clock, so
they can't represent certain CEA/HDMI modes accurately. If we see a mode
coming in via detailed timings which otherwise matches one of the
CEA/HDMI modes except the clock is just a bit off, let's assume that the
intention was for that mode to be one of the CEA/HDMI modes and go ahead
and fix up the clock to match the CEA/HDMI spec exactly (well, as close
as we can get with the 1 kHz resolution we use).

This should help code that's looking for an exact clock match (eg. i915
audio N/CTS setup).

Cc: Adam Jackson <ajax@redhat.com>
Cc: Clint Taylor <clinton.a.taylor@intel.com>
Cc: Libin Yang <libin.yang@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Ville Syrjälä 2015-10-08 11:43:32 +03:00 committed by Daniel Vetter
parent affa0e033b
commit fa3a7340ea
1 changed files with 48 additions and 0 deletions
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48
drivers/gpu/drm/drm_edid.c
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@ -2418,6 +2418,8 @@ add_cvt_modes(struct drm_connector *connector, struct edid *edid)
return closure.modes;
}
static void fixup_detailed_cea_mode_clock(struct drm_display_mode *mode);
static void
do_detailed_mode(struct detailed_timing *timing, void *c)
{
@ -2434,6 +2436,13 @@ do_detailed_mode(struct detailed_timing *timing, void *c)
if (closure->preferred)
newmode->type |= DRM_MODE_TYPE_PREFERRED;
/*
* Detailed modes are limited to 10kHz pixel clock resolution,
* so fix up anything that looks like CEA/HDMI mode, but the clock
* is just slightly off.
*/
fixup_detailed_cea_mode_clock(newmode);
drm_mode_probed_add(closure->connector, newmode);
closure->modes++;
closure->preferred = 0;
@ -3103,6 +3112,45 @@ add_cea_modes(struct drm_connector *connector, struct edid *edid)
return modes;
}
static void fixup_detailed_cea_mode_clock(struct drm_display_mode *mode)
{
const struct drm_display_mode *cea_mode;
int clock1, clock2, clock;
u8 mode_idx;
const char *type;
mode_idx = drm_match_cea_mode(mode) - 1;
if (mode_idx < ARRAY_SIZE(edid_cea_modes)) {
type = "CEA";
cea_mode = &edid_cea_modes[mode_idx];
clock1 = cea_mode->clock;
clock2 = cea_mode_alternate_clock(cea_mode);
} else {
mode_idx = drm_match_hdmi_mode(mode) - 1;
if (mode_idx < ARRAY_SIZE(edid_4k_modes)) {
type = "HDMI";
cea_mode = &edid_4k_modes[mode_idx];
clock1 = cea_mode->clock;
clock2 = hdmi_mode_alternate_clock(cea_mode);
} else {
return;
}
}
/* pick whichever is closest */
if (abs(mode->clock - clock1) < abs(mode->clock - clock2))
clock = clock1;
else
clock = clock2;
if (mode->clock == clock)
return;
DRM_DEBUG("detailed mode matches %s VIC %d, adjusting clock %d -> %d\n",
type, mode_idx + 1, mode->clock, clock);
mode->clock = clock;
}
static void
parse_hdmi_vsdb(struct drm_connector *connector, const u8 *db)
{