linux-kernel - [PATCH] drm/edid: add a quirk for two 240Hz Samsung monitors

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Date:   Wed, 1 Nov 2023 17:00:36 -0400
From:   Hamza Mahfooz <hamza.mahfooz@....com>
To:     <dri-devel@...ts.freedesktop.org>
CC:     <amd-gfx@...ts.freedesktop.org>,
        Alex Deucher <alexander.deucher@....com>,
        Aurabindo Pillai <aurabindo.pillai@....com>,
        Jerry Zuo <jerry.zuo@....com>,
        Hamza Mahfooz <hamza.mahfooz@....com>,
        <stable@...r.kernel.org>,
        "Harry Wentland" <harry.wentland@....com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] drm/edid: add a quirk for two 240Hz Samsung monitors

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)
 
 #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