On 2019-11-21 8:40 a.m., Kazlauskas, Nicholas wrote:
On 2019-11-21 3:31 a.m., Li, Ching-shih (Louis) wrote:
Hi reviewers,
What is the review result for this patch? Customer is pushing on this
change to merge. TKS for your attention.
BR,
Louis
-----Original Message-----
From: Louis Li <Ching-shih.Li@xxxxxxx>
Sent: Thursday, November 14, 2019 11:42 AM
To: amd-gfx@xxxxxxxxxxxxxxxxxxxxx
Cc: Kazlauskas, Nicholas <Nicholas.Kazlauskas@xxxxxxx>; Wentland,
Harry <Harry.Wentland@xxxxxxx>; Li, Ching-shih (Louis)
<Ching-shih.Li@xxxxxxx>
Subject: [PATCH v2] drm/amd/display: Fix Apple dongle cannot be
successfully detected
[Why]
External monitor cannot be displayed consistently, if connecting via
this Apple dongle (A1621, USB Type-C to HDMI).
By experiments, it is confirmed that the dongle needs 200ms at least
to be ready for communication, after it sets HPD signal high.
[How]
When receiving HPD IRQ, delay 300ms at the beginning of handle_hpd_irq().
Then run the original procedure.
With this patch applied, the problem cannot be reproduced.
With other dongles, test results are PASS.
Test result is PASS to plug in HDMI cable while playing video, and the
video is being playing smoothly.
Test result is PASS after system resumes from suspend.
Signed-off-by: Louis Li <Ching-shih.Li@xxxxxxx>
This is still a NAK from me since the logic hasn't changed from the
first patch.
Sleeps don't belong in IRQ handlers.
Regards,
Nicholas Kazlauskas
Actually, this lives in the low IRQ context which means that it's
already been queued off to a work thread so it's safe to sleep.
I'm not sure we want a general 300ms sleep (even by experiment you said
that it only needed 200ms) for all connectors.
Nicholas Kazlauskas
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 0aef92b7c037..5b844b6a5a59 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1025,6 +1025,11 @@ static void handle_hpd_irq(void *param)
struct drm_device *dev = connector->dev;
enum dc_connection_type new_connection_type = dc_connection_none;
+ /* Some monitors/dongles need around 200ms to be ready for
communication
+ * after those devices drive HPD signal high.
+ */
+ msleep(300);
+
/* In case of failure or MST no need to update connector status
or notify the OS
* since (for MST case) MST does this in it's own context.
*/
--
2.21.0
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