This is to eliminate all cases of "*ERROR* LSPCON mode hasn't settled",
followed by link training errors. Intel engineers recommended increasing
this timeout and that does resolve the issue.
On some CometLake-based device designs the Parade PS175 takes more than
400ms to settle in PCON mode. 100 reboot trials on one device resulted
in a median settle time of 440ms and a maximum of 444ms. Even after
increasing the timeout to 500ms, 2% of devices still had this error. So
this increases the timeout to 800ms.
Signed-off-by: Pablo Ceballos <pcebal...@google.com>
---
V2: Added more details in the commit message
V3: Only apply the increased timeout if the vendor is Parade
drivers/gpu/drm/i915/display/intel_lspcon.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/display/intel_lspcon.c
b/drivers/gpu/drm/i915/display/intel_lspcon.c
index bb3b5355a0d9..b07eab84cc63 100644
--- a/drivers/gpu/drm/i915/display/intel_lspcon.c
+++ b/drivers/gpu/drm/i915/display/intel_lspcon.c
@@ -153,6 +153,24 @@ static enum drm_lspcon_mode lspcon_get_current_mode(struct
intel_lspcon *lspcon)
return current_mode;
}
+static u32 lspcon_get_mode_settle_timeout(struct intel_lspcon *lspcon)
+{
+ u32 timeout_ms = 400;
+
+ /*
+ * On some CometLake-based device designs the Parade PS175 takes more
+ * than 400ms to settle in PCON mode. 100 reboot trials on one device
+ * resulted in a median settle time of 440ms and a maximum of 444ms.
+ * Even after increasing the timeout to 500ms, 2% of devices still had
+ * this error. So this sets the timeout to 800ms.
+ */
+ if (lspcon->vendor == LSPCON_VENDOR_PARADE)
+ timeout_ms = 800;
+
+ return timeout_ms;
+}
+
+
static enum drm_lspcon_mode lspcon_wait_mode(struct intel_lspcon *lspcon,
enum drm_lspcon_mode mode)
{
@@ -167,7 +185,8 @@ static enum drm_lspcon_mode lspcon_wait_mode(struct
intel_lspcon *lspcon,
drm_dbg_kms(&i915->drm, "Waiting for LSPCON mode %s to settle\n",
lspcon_mode_name(mode));
- wait_for((current_mode = lspcon_get_current_mode(lspcon)) == mode, 400);
+ wait_for((current_mode = lspcon_get_current_mode(lspcon)) == mode,
+ lspcon_get_mode_settle_timeout(lspcon));
if (current_mode != mode)
drm_err(&i915->drm, "LSPCON mode hasn't settled\n");
--
2.39.2
