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Message-ID: <87edh84is9.fsf@intel.com>
Date: Thu, 02 Nov 2023 11:16:22 +0200
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: Alex Deucher <alexdeucher@...il.com>,
Hamza Mahfooz <hamza.mahfooz@....com>
Cc: Maxime Ripard <mripard@...nel.org>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
stable@...r.kernel.org, Jerry Zuo <jerry.zuo@....com>,
Aurabindo Pillai <aurabindo.pillai@....com>,
amd-gfx@...ts.freedesktop.org,
Thomas Zimmermann <tzimmermann@...e.de>,
Alex Deucher <alexander.deucher@....com>,
Ville Syrjälä <ville.syrjala@...ux.intel.com>
Subject: Re: [PATCH] drm/edid: add a quirk for two 240Hz Samsung monitors
On Wed, 01 Nov 2023, Alex Deucher <alexdeucher@...il.com> wrote:
> On Wed, Nov 1, 2023 at 5:01 PM Hamza Mahfooz <hamza.mahfooz@....com> wrote:
>>
>> Without this fix the 5120x1440@240 timing of these monitors
>> leads to screen flickering.
>>
>> Cc: stable@...r.kernel.org # 6.1+
>> Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1442
>> Co-developed-by: Harry Wentland <harry.wentland@....com>
>> Signed-off-by: Harry Wentland <harry.wentland@....com>
>> Signed-off-by: Hamza Mahfooz <hamza.mahfooz@....com>
>> ---
>> drivers/gpu/drm/drm_edid.c | 47 +++++++++++++++++++++++++++++++++++---
>> 1 file changed, 44 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
>> index bca2af4fe1fc..3fdb8907f66b 100644
>> --- a/drivers/gpu/drm/drm_edid.c
>> +++ b/drivers/gpu/drm/drm_edid.c
>> @@ -89,6 +89,8 @@ static int oui(u8 first, u8 second, u8 third)
>> #define EDID_QUIRK_NON_DESKTOP (1 << 12)
>> /* Cap the DSC target bitrate to 15bpp */
>> #define EDID_QUIRK_CAP_DSC_15BPP (1 << 13)
>> +/* Fix up a particular 5120x1440@...Hz timing */
>> +#define EDID_QUIRK_FIXUP_5120_1440_240 (1 << 14)
>
> What is wrong with the original timing that needs to be fixed?
Indeed. I'd be wary of applying this quirk as-is, because it'll impact
all drivers and all connectors.
The bug report does not have a single EDID from the affected displays
attached.
The quirk sets mode members that apparently do not need to be modified.
Cc: Ville
BR,
Jani.
>
> Alex
>
>
>>
>> #define MICROSOFT_IEEE_OUI 0xca125c
>>
>> @@ -170,6 +172,12 @@ static const struct edid_quirk {
>> EDID_QUIRK('S', 'A', 'M', 596, EDID_QUIRK_PREFER_LARGE_60),
>> EDID_QUIRK('S', 'A', 'M', 638, EDID_QUIRK_PREFER_LARGE_60),
>>
>> + /* Samsung C49G95T */
>> + EDID_QUIRK('S', 'A', 'M', 0x7053, EDID_QUIRK_FIXUP_5120_1440_240),
>> +
>> + /* Samsung S49AG95 */
>> + EDID_QUIRK('S', 'A', 'M', 0x71ac, EDID_QUIRK_FIXUP_5120_1440_240),
>> +
>> /* Sony PVM-2541A does up to 12 bpc, but only reports max 8 bpc */
>> EDID_QUIRK('S', 'N', 'Y', 0x2541, EDID_QUIRK_FORCE_12BPC),
>>
>> @@ -6586,7 +6594,37 @@ static void update_display_info(struct drm_connector *connector,
>> drm_edid_to_eld(connector, drm_edid);
>> }
>>
>> -static struct drm_display_mode *drm_mode_displayid_detailed(struct drm_device *dev,
>> +static void drm_mode_displayid_detailed_edid_quirks(struct drm_connector *connector,
>> + struct drm_display_mode *mode)
>> +{
>> + unsigned int hsync_width;
>> + unsigned int vsync_width;
>> +
>> + if (connector->display_info.quirks & EDID_QUIRK_FIXUP_5120_1440_240) {
>> + if (mode->hdisplay == 5120 && mode->vdisplay == 1440 &&
>> + mode->clock == 1939490) {
>> + hsync_width = mode->hsync_end - mode->hsync_start;
>> + vsync_width = mode->vsync_end - mode->vsync_start;
>> +
>> + mode->clock = 2018490;
>> + mode->hdisplay = 5120;
>> + mode->hsync_start = 5120 + 8;
>> + mode->hsync_end = 5120 + 8 + hsync_width;
>> + mode->htotal = 5200;
>> +
>> + mode->vdisplay = 1440;
>> + mode->vsync_start = 1440 + 165;
>> + mode->vsync_end = 1440 + 165 + vsync_width;
>> + mode->vtotal = 1619;
>> +
>> + drm_dbg_kms(connector->dev,
>> + "[CONNECTOR:%d:%s] Samsung 240Hz mode quirk applied\n",
>> + connector->base.id, connector->name);
>> + }
>> + }
>> +}
>> +
>> +static struct drm_display_mode *drm_mode_displayid_detailed(struct drm_connector *connector,
>> struct displayid_detailed_timings_1 *timings,
>> bool type_7)
>> {
>> @@ -6605,7 +6643,7 @@ static struct drm_display_mode *drm_mode_displayid_detailed(struct drm_device *d
>> bool hsync_positive = (timings->hsync[1] >> 7) & 0x1;
>> bool vsync_positive = (timings->vsync[1] >> 7) & 0x1;
>>
>> - mode = drm_mode_create(dev);
>> + mode = drm_mode_create(connector->dev);
>> if (!mode)
>> return NULL;
>>
>> @@ -6628,6 +6666,9 @@ static struct drm_display_mode *drm_mode_displayid_detailed(struct drm_device *d
>>
>> if (timings->flags & 0x80)
>> mode->type |= DRM_MODE_TYPE_PREFERRED;
>> +
>> + drm_mode_displayid_detailed_edid_quirks(connector, mode);
>> +
>> drm_mode_set_name(mode);
>>
>> return mode;
>> @@ -6650,7 +6691,7 @@ static int add_displayid_detailed_1_modes(struct drm_connector *connector,
>> for (i = 0; i < num_timings; i++) {
>> struct displayid_detailed_timings_1 *timings = &det->timings[i];
>>
>> - newmode = drm_mode_displayid_detailed(connector->dev, timings, type_7);
>> + newmode = drm_mode_displayid_detailed(connector, timings, type_7);
>> if (!newmode)
>> continue;
>>
>> --
>> 2.42.0
>>
--
Jani Nikula, Intel
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