Re: 回复: [REGRESSION] amdgpu: async system error exception from hdp_v5_0_flush_hdp()

["Alexey Klimov" <alexey.klimov@linaro.org>]

On Tue Apr 22, 2025 at 2:00 PM BST, Alex Deucher wrote:
> On Mon, Apr 21, 2025 at 10:21 PM Alexey Klimov <alexey.klimov@linaro.org> wrote:
>>
>> On Thu Apr 17, 2025 at 2:08 PM BST, Alex Deucher wrote:
>> > On Wed, Apr 16, 2025 at 8:43 PM Fugang Duan <fugang.duan@cixtech.com> wrote:
>> >>
>> >> 发件人: Alex Deucher <alexdeucher@gmail.com> 发送时间: 2025年4月16日 22:49
>> >> >收件人: Alexey Klimov <alexey.klimov@linaro.org>
>> >> >On Wed, Apr 16, 2025 at 9:48 AM Alexey Klimov <alexey.klimov@linaro.org> wrote:
>> >> >>
>> >> >> On Wed Apr 16, 2025 at 4:12 AM BST, Fugang Duan wrote:
>> >> >> > 发件人: Alexey Klimov <alexey.klimov@linaro.org> 发送时间: 2025年4月16
>> >> >日 2:28
>> >> >> >>#regzbot introduced: v6.12..v6.13
>> >> >> >>The only change related to hdp_v5_0_flush_hdp() was
>> >> >> >>cf424020e040 drm/amdgpu/hdp5.0: do a posting read when flushing HDP
>> >> >> >>
>> >> >> >>Reverting that commit ^^ did help and resolved that problem. Before

[..]

>> > OK.  that patch won't change anything then.  Can you try this patch instead?
>>
>> Config I am using is basically defconfig wrt memory parameters, yeah, i use 4k.
>>
>> So I tested that patch, thank you, and some other different configurations --
>> nothing helped. Exactly the same behaviour with the same backtrace.
>
> Did you test the first (4k check) or the second (don't remap on ARM) patch?

The second one. I think you mentioned that first one won't help for 4k pages.


>> So it seems that it is firmware problem after all?
>
> There is no GPU firmware involved in this operation.  It's just a
> posted write.  E.g., we write to a register to flush the HDP write
> queue and then read the register back to make sure the write posted.
> If the second patch didn't help, then perhaps there is some issue with
> MMIO access on your platform?

I didn't mean GPU firmware at all. I only had uefi/EL3 firmwares in mind.

Completely out of the blue, based on nothing, do you think that
adding delay/some mem barrier between write and read might help?
I wonder if host data path code should be executed during common desktop
usage as a common user then why it doesn't break later. But yeah, I also
think this is this motherboard problem. Thank you.

Thanks,
Alexey