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
Cc: Jani Nikula jani.nikula@intel.com Cc: Cooper Chiou cooper.chiou@intel.com Cc: Matt Atwood matthew.s.atwood@intel.com Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Dhinakaran Pandiyan dhinakaran.pandiyan@intel.com Cc: Clint Taylor clinton.a.taylor@intel.com Signed-off-by: Lee, Shawn C shawn.c.lee@intel.com --- 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