Hi Chun-Kuang,

Missatge de Chun-Kuang Hu [off-list ref] del dia dt., 21 de
set. 2021 a les 15:15:

Hi, Enric:

Enric Balletbo Serra [off-list ref] 於 2021年9月21日 週二 下午4:36寫道：

quoted

Hi Chun-Kuang,

(again without html format, sorry for the noise)

Missatge de Chun-Kuang Hu [off-list ref] del dia dj., 12
d’ag. 2021 a les 2:13:

quoted

Chun-Kuang Hu [off-list ref] 於 2021年8月9日 週一 上午7:47寫道：

quoted

These refinements include using standard mailbox callback interface,
timeout detection, and a fixed cmdq_handle.

For this series, applied to mediatek-drm-next [1].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-next

These patches seem to break the display on the Acer Chromebook R 13
(MT8173) in the current mainline. After running a bisection it pointed
me to the following commit

commit f4be17cd5b14dd73545b0e014a63ebe9ab5ef837
Author: Chun-Kuang Hu [off-list ref]
Date:   Sun Jul 4 15:36:48 2021 +0800

    drm/mediatek: Remove struct cmdq_client

Reverting this patch alone is not trivial, so I ended up reverting the
full series, and I can confirm that reverting the full series makes
the display work again.

I think you could not just revert "drm/mediatek: Remove struct
cmdq_client", you should also revert the patches after it, such as

"drm/mediatek: Clear pending flag when cmdq packet is done"
"drm/mediatek: Add cmdq_handle in mtk_crtc"
"drm/mediatek: Detect CMDQ execution timeout"

Yes, in fact I reverted:

9efb16c2fdd6 drm/mediatek: Clear pending flag when cmdq packet is done
bc9241be73d9 drm/mediatek: Add cmdq_handle in mtk_crtc
8cdcb3653424 drm/mediatek: Detect CMDQ execution timeout
f4be17cd5b14 drm/mediatek: Remove struct cmdq_client
c1ec54b7b5af drm/mediatek: Use mailbox rx_callback instead of cmdq_task_cb

Without these patches 5.15-rc2 works again on my platform.

The commit 'c1ec54b7b5af drm/mediatek: Use mailbox rx_callback instead
of cmdq_task_cb' alone introduces lots of warnings in the kernel

WARNING: CPU: 0 PID: 0 at drivers/mailbox/mtk-cmdq-mailbox.c:198
cmdq_task_exec_done+0xb8/0xe0

I think is just a leftover or the mentioned warning, but that confused
me a bit doing the bisection. Then, after commit 'f4be17cd5b14
drm/mediatek: Remove struct cmdq_client' my system simply gets stuck.
For now I don't see any obvious mistake but will dig further.

Can I ask you in which platform did you test? And if you can double
check if your platform is broken too in current mainline?

Thanks,
  Enric

If "drm/mediatek: Remove struct cmdq_client" is the patch cause
display abnormal, I think you could compare code w/ and w/o this
patch. Focus on the value accuracy, such as cmdq_cl and cmdq_chan. And
focus on the flow accuracy, such as mtk_drm_crtc_update_config() and
ddp_cmdq_cb(). If this could not find the problem, I think the latest
way is to break this patch into small patches, changes little in each
small patches and we could finally find out the problem.

Regards,
Chun-Kuang.

quoted

Unfortunately, after the merge window, different things broke for this
device, and I didn't finish isolating them, and it is not clear to me
yet whether the logs I'm getting are useful for this specific issue or
not. Basically with this series merged the kernel seems to be stuck,
and the display is not working. Latest message is

[   12.329173] mtk-iommu 10205000.iommu: Partial TLB flush timed out,
falling back to full flush

Without the series, the kernel goes far and display works, however
there are other issues affecting the cros-ec, but I think that's
another issue.

I'll try to dig a bit more, but, meanwhile, if you have any idea
please let me know.

Thanks,
 Enric

quoted

Regards,
Chun-Kuang.

quoted

Changes in v2:
1. Define mtk_drm_cmdq_pkt_create() and mtk_drm_cmdq_pkt_destroy()
   when CONFIG_MTK_CMDQ is reachable.

Chun-Kuang Hu (4):
  drm/mediatek: Use mailbox rx_callback instead of cmdq_task_cb
  drm/mediatek: Remove struct cmdq_client
  drm/mediatek: Detect CMDQ execution timeout
  drm/mediatek: Add cmdq_handle in mtk_crtc

 drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 110 ++++++++++++++++++++----
 1 file changed, 91 insertions(+), 19 deletions(-)

--
2.25.1

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