On 14/02/2022 17:06, Alyssa Rosenzweig wrote:
On Mon, Feb 14, 2022 at 04:23:18PM +0000, Steven Price wrote:
On 11/02/2022 20:27, alyssa.rosenzweig@collabora.com wrote:
From: Alyssa Rosenzweig alyssa.rosenzweig@collabora.com
Some Valhall GPUs require resets when encountering bus faults due to occlusion query writes. Add the issue bit for this and handle it.
Signed-off-by: Alyssa Rosenzweig alyssa.rosenzweig@collabora.com
Reviewed-by: Steven Price steven.price@arm.com (although one nit below)
Just in case any one is wondering - these bus faults occur when switching the GPU's MMU to unmapped - it's not a normal "bus fault" from the external bus. This is triggered by an attempt to read unmapped memory which is completed by the driver by switching the entire MMU to unmapped.
Ouch, that's subtle.
diff --git a/drivers/gpu/drm/panfrost/panfrost_issues.h b/drivers/gpu/drm/panfrost/panfrost_issues.h index a66692663833..058f6a4c8435 100644 --- a/drivers/gpu/drm/panfrost/panfrost_issues.h +++ b/drivers/gpu/drm/panfrost/panfrost_issues.h @@ -128,6 +128,10 @@ enum panfrost_hw_issue { /* Must set SC_VAR_ALGORITHM */ HW_ISSUE_TTRX_2968_TTRX_3162,
- /* Bus fault from occlusion query write may cause future fragment jobs
* to hang */NIT: Kernel comment style has the "/*" and "*/" on lines by themselves for multi-line comments. checkpatch will complain!
Yes, I am aware (and checkpatch did complain). The existing multi-line comments in that file do not have the extra lines. Consistency within the file seemed like the lesser evil. If you think it's better to appease checkpatch, I can reformat for v2.
(I can also throw in a patch fixing the rest of that file's multiline comments but that seems a bit extra.)
Nah! I've never been very keen on that style rule myself, but I usually try to keep checkpatch happy when working on the kernel. Lets just follow the rest of the file for now.
Thanks,
Steve