The N value was computed by kernel driver that based on synchronous clock
mode. But only specific N value (0x8000) would be acceptable for
LG LP140WF6-SPM1 eDP panel which is running at asynchronous clock mode.
With the other N value, Tcon will enter BITS mode and display black screen.
Add this panel into quirk database and give particular N value when
calculate M/N divider.
v2: no update
v3: add lost commit messages back for version 2
v4: send patch to both intel-gfx and dri-devel
Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
Cc: Cooper Chiou <cooper.chiou@xxxxxxxxx>
Cc: Matt Atwood <matthew.s.atwood@xxxxxxxxx>
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
Cc: Clint Taylor <clinton.a.taylor@xxxxxxxxx>
Signed-off-by: Lee, Shawn C <shawn.c.lee@xxxxxxxxx>
---
drivers/gpu/drm/drm_dp_helper.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index f3a7563eb8a1..67d683453f1c 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -1270,6 +1270,8 @@ struct dpcd_quirk {
static const struct dpcd_quirk dpcd_quirk_list[] = {
/* Analogix 7737 needs reduced M and N at HBR2 link rates */
{ OUI(0x00, 0x22, 0xb9), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_CONSTANT_N) },
+ /* LG LP140WF6-SPM1 eDP panel */
+ { OUI(0x00, 0x22, 0xb9), DEVICE_ID('s', 'i', 'v', 'a', 'r', 'T'), false, BIT(DP_DPCD_QUIRK_CONSTANT_N) },
};
#undef OUI
--
2.7.4
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