Re: [RFC PATCH] drm/radeon: increase d3 delay to 20 ms during switcheroo poweron

[Maarten Lankhorst <maarten.lankhorst@canonical.com>]

Op 04-01-13 16:34, Alex Deucher schreef:
> On Wed, Jan 2, 2013 at 10:38 AM, Maarten Lankhorst
> <maarten.lankhorst@canonical.com> wrote:
>> vga-switcheroo with apple-gmux does not switch correctly on my system. The PCI
>> configuration space is not restored correctly, resulting in MSI not working after switch.
>>
>> Only useful item in dmesg is:
>>
>> [   33.922807] radeon 0000:01:00.0: Refused to change power state, currently in D3
>>
>> I did some testing, dumping the difference in ms between first succesful switch
>> from D3 to D0, and it seems that there is slightly more than 20 ms difference when
>> the device is re-enabled through vga-switcheroo.
>>
>> So bump the re-enable d3 delay to 20 ms to handle this, which fixes msi not working
>> on my system after switcheroo-ing.
> I guess if it fixes it...  Has anyone seen similar problems on non-mac
> systems?  What is the delay normally set to?  It seems pretty
It's normally set to PCI_PM_D3_WAIT, 10 ms.
> innocuous other than potentially adding a little extra latency.  Do
> you think it makes sense to make it more like a quirk and only apply
> it to problematic systems or just apply across the board?
Quirking would be fine. Since there is a message in dmesg it would
be easy to identify when others hit the same issue, in which case
we could enable it all the time.

>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
>>
>> ---
>>
>> This is a RFC patch since I feel what I'm doing is done in a hackish way,
>> but it seems only the D3->D0 transition during switcheroo enable is affected,
>> other transitions like suspend/resume and switcheroo poweroff seem unaffected.
>>
>> diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
>> index 5515921..8816958 100644
>> --- a/drivers/gpu/drm/radeon/radeon_device.c
>> +++ b/drivers/gpu/drm/radeon/radeon_device.c
>> @@ -910,10 +910,19 @@ static void radeon_switcheroo_set_state(struct pci_dev *pdev, enum vga_switchero
>>         struct drm_device *dev = pci_get_drvdata(pdev);
>>         pm_message_t pmm = { .event = PM_EVENT_SUSPEND };
>>         if (state == VGA_SWITCHEROO_ON) {
>> +               unsigned d3_delay = dev->pdev->d3_delay;
>> +
>>                 printk(KERN_INFO "radeon: switched on\n");
>>                 /* don't suspend or resume card normally */
>>                 dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
>> +
>> +               if (dev->pdev->d3_delay < 20)
>> +                       dev->pdev->d3_delay = 20;
>> +
>>                 radeon_resume_kms(dev);
>> +
>> +               dev->pdev->d3_delay = d3_delay;
>> +
>>                 dev->switch_power_state = DRM_SWITCH_POWER_ON;
>>                 drm_kms_helper_poll_enable(dev);
>>         } else {
>>