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Message-ID: <CADnq5_OUjbrVOmSr7vuK8h8rmg+q14ra1jiE+B0TRfZos-jn5w@mail.gmail.com>
Date: Thu, 2 Nov 2023 15:06:14 -0400
From: Alex Deucher <alexdeucher@...il.com>
To: Hamza Mahfooz <hamza.mahfooz@....com>
Cc: dri-devel@...ts.freedesktop.org,
Maxime Ripard <mripard@...nel.org>,
amd-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
stable@...r.kernel.org, Jerry Zuo <jerry.zuo@....com>,
Aurabindo Pillai <aurabindo.pillai@....com>,
Thomas Zimmermann <tzimmermann@...e.de>,
Alex Deucher <alexander.deucher@....com>
Subject: Re: [PATCH] drm/edid: add a quirk for two 240Hz Samsung monitors
On Thu, Nov 2, 2023 at 3:00 PM Hamza Mahfooz <hamza.mahfooz@....com> wrote:
>
> On 11/1/23 17:36, Alex Deucher 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?
>
> Apparently, all of timing values for the 5120x1440@240 mode of these
> monitors aren't set correctly (they are all lower than they should be)
> in their EDIDs. For what it's worth, the windows driver has had a quirk
> similar the one proposed in this patch for ~2 years.
It would be good to at least include the original mode timings from
the EDID and the new ones added by the quirk in the commit message and
a description of why they are problematic and why the new ones work.
Alex
>
> >
> > 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
> >>
> --
> Hamza
>
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