Re: [PATCH 2/2] drm/xe/hwmon: Increase timeout for mailbox power limits

["Poosa, Karthik" <karthik.poosa@intel.com>]

On 31-08-2026 19:28, Rodrigo Vivi wrote:
> On Mon, Aug 31, 2026 at 09:41:45AM +0200, Raag Jadav wrote:
>> On Mon, Aug 31, 2026 at 12:39:50PM +0530, Tauro, Riana wrote:
>>> On 31-08-2026 12:24, Poosa, Karthik wrote:
>>>> On 31-08-2026 10:59, Tauro, Riana wrote:
>>>>> On 29-07-2026 22:45, Karthik Poosa wrote:
>>>>>> Mailbox power limit operations can occasionally take longer than the
>>>>>> current 1 ms timeout, causing sporadic failures.
>> Why?
>>
>>>>>> Increase the timeout to 10 ms and rename PL_WRITE_MBX_TIMEOUT_MS to
>>>>>> PL_MBX_TIMEOUT_MS to better reflect its usage.
>>>>> Why is the timeout applicable only for power and not the other
>>>>> attribute reads?
>>>> Because the timeout is seen only with mailbox power limit commands only,
>>>> default 1ms timeout wasn't enough here.
>>> Any reason why this is not seen for the other reads?
>> +1, these things should be coming from a hard spec with valid technical
>> justification and not some random email asking us to do so.
> Well, you have such high expectations :)
> Sometimes we have to live with the empirical... while we hunt other teams asking
> them to do their job correctly, of course...
>
> Interestingly enough, I just found in some of the many spread pcode docs:
>
> driver_to_pcode_mailbox_spec.html#mailbox-response-time
>
> """
> Mailbox response time
> Mailbox response timeout shoudl be set to 10ms as worst case.
> """
>
> Perhaps we should simply change the default to 10ms.

Investigation is ongoing to understand why some pcode mailbox commands 
occasionally take longer to complete.

Until then, using the documented worst-case timeout as default timeout 
seems the better approach.

>
>> Raag