Re: [PATCH v5] drm/xe: Poll GT for C6 before D3

["Belgaumkar, Vinay" <vinay.belgaumkar@intel.com>]

On 9/16/2026 5:21 AM, Rodrigo Vivi wrote:
> On Tue, Sep 15, 2026 at 09:20:50PM +0000, sashiko-bot@kernel.org wrote:
>> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
>> - [Medium] drm/xe: D3cold runtime suspend always fails due to C6 check after GT PG disable
>> --
>>
>> commit 691645f0da262033183939383983163842757c50
>> Author: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
>>
>> drm/xe: Poll GT for C6 before D3
>>
>> This commit adds a check for GT C6 state before the D3 transition in the
>> runtime suspend flow, aborting and resuming if the check fails.
>>
>>> diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
>>> index 00b2b5dfb8f6c..488745ce0473f 100644
>>> --- a/drivers/gpu/drm/xe/xe_pci.c
>>> +++ b/drivers/gpu/drm/xe/xe_pci.c
>> [ ... ]
>>> @@ -1394,6 +1394,17 @@ static int xe_pci_runtime_suspend(struct device *dev)
>>>   	if (err)
>>>   		return err;
>>>   
>>> +	err = xe_pm_check_device_idle(xe);
>>> +	if (err) {
>>> +		drm_dbg(&xe->drm, "Resuming - Device idle check failed!");
>>> +		ret = xe_pm_runtime_resume(xe);
>> [Severity: Medium]
>> Will this idle check always fail when D3cold is allowed?
>>
>> Looking at the sequence, xe_pci_runtime_suspend() calls
>> xe_pm_runtime_suspend() right before this check. When D3cold is allowed,
>> xe_pm_runtime_suspend() executes xe_gt_suspend():
>>
>> drivers/gpu/drm/xe/xe_pm.c:xe_pm_runtime_suspend() {
>> ...
>> 	for_each_gt(gt, xe, id) {
>> 		err = xe->d3cold.allowed ? xe_gt_suspend(gt) : xe_gt_runtime_suspend(gt);
>> ...
>> }
>>
>> xe_gt_suspend() then prepares the GT for power removal by explicitly disabling
>> power gating:
>>
>> drivers/gpu/drm/xe/xe_gt.c:xe_gt_suspend() {
>> ...
>> 	xe_gt_idle_disable_pg(gt);
>> ...
>> }
>>
>> Because xe_gt_idle_disable_pg() writes 0 to the POWERGATE_ENABLE register,
>> the hardware is prevented from entering the C6 power gating state. Won't
>> the subsequent poll for GT_IDLE_C6 in xe_pm_check_device_idle() always
>> timeout and return -EAGAIN, causing the device to constantly abort suspend
>> and immediately resume?
> I believe this can be dismissed. But it would be good to run some experiments
> to confirm this.
> If this is right, then the CRI bug is a different FW bug...

Disabling render/media power gating does not block C6 in any way. This 
is a non-issue as you mentioned.

Thanks,

Vinay.

>
>> -- 
>> Sashiko AI review · https://sashiko.dev/#/patchset/20260915210113.2915363-1-vinay.belgaumkar@intel.com?part=1