Re: [PATCH v2 3/3] drm/gma500: Fix (vblank) IRQs not working after suspend/resume

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Hi,

On 9/9/22 09:34, Patrik Jakobsson wrote:
> On Thu, Sep 8, 2022 at 3:39 PM Hans de Goede
> <hdegoede@xxxxxxxxxx> wrote:
>>
>> Hi,
>>
>> On 9/8/22 15:26, Patrik Jakobsson wrote:
>>> On Tue, Sep 6, 2022 at 10:38 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>>>>
>>>> Fix gnome-shell (and other page-flip users) hanging after suspend/resume
>>>> because of the gma500's IRQs not working.
>>>>
>>>> This fixes 2 problems with the IRQ handling:
>>>>
>>>> 1. gma_power_off() calls gma_irq_uninstall() which does a free_irq(), but
>>>>    gma_power_on() called gma_irq_preinstall() + gma_irq_postinstall() which
>>>>    do not call request_irq. Replace the pre- + post-install calls with
>>>>    gma_irq_install() which does prep + request + post.
>>>
>>> Hmm, I don't think we're supposed to do free_irq() during suspend in
>>> the first place. request_irq() and free_irq() are normally only called
>>> in the pci device probe/remove hooks. Same is true for msi
>>> enable/disable.
>>
>> Right. I first tried to switch to disable_irq() / enable_irq() which are
>> expected to be used during suspend/resume. That did resolve the issue
>> of there no longer being an IRQ handler registered after suspend/resume,
>> but the IRQ still would no longer fire after a suspend/resume.
> 
> The irq enable/disable is handled by writing PSB_INT_ENABLE_R in
> gma_irq_install/uninstall(). Also using disable_irq() and enable_irq()
> shouldn't be required. But the docs could be wrong and this might fix
> the interrupts I'm seeing on PSB after resume.

That just disables the sender of the IRQ, where as disable_irq()
disables the IRQ at the receiving end. And the sending end goes
in full powerdown during suspend, after which the IRQ line might
float or be pulled in a specific direction by the powered-down
display-engine block.

So yes this might be the cause of the "irq 16: nobody cared"
message.

Note that on the Packard Bell Dot SC when I disable MSI the
IRQ line is shared with an UHCI controller, so that might
be part of the problem here too.

>> So then I tried the pci_disable_msi() + pci_enable_msi() and that
>> did the trick. And since we should not call pci_disable_msi() with an
>> IRQ handler registered I decided to keep the free_irq + request_irq
>> over suspend/resume.
> 
> Ok, then I understand your motivation for the free/request dance.
> However, I would argue that if this problem is specific to your
> Packard Bell Dot SC it is better handled with a quirk.

I only have the one machine to test on. But the Packard Bell Dot SC
is actually a rebrand of the somewhat popular Acer Aspire One D270
up to the point where they both use the same BIOS updater. So if we
go with a quirk this should at least also apply to the Acer AOD270,
but I expect more models to be impacted by this. Typically the BIOS-es
on these devices are a copy & paste job from some reference
implementation.

And this workaround should work fine on machines which don't stricly
need it too. So my preference would be to just do this everywhere.

>> Another option is to never call pci_enable_msi() and use APIC style
>> IRQs instead. At least on the Packard Bell Dot SC (cedarview) that
>> works.
> 
> Yes, the quirk could be to not use MSI on the Packard Bell Dot SC. But
> let me check this on other Cedarview systems first.

Not using MSI means sharing the IRQ, which although it should work fine
is better to avoid.

I wonder if you have ever tried enabling MSI on a poulsebo machine ?

>>> I can take this patch as is since it improves on the current situation
>>> but feel free to dig deeper if you like.
>>
>> I'm not sure what else I can do to dig deeper though. TBH I'm happy
>> I managed to come up with something which works at all.
> 
> Digging deeper would be to figure out why pci_restore_msi_state() is
> not doing its job.

Yes that would be an option. I suspect that the issue actually a setting
on the PCI host bridge side which gets poked by the BIOS during S3
suspend and pci_restore_msi_state() presumable only touched
the devices state.  While pci_enable_msi() (presumably) also re-does
the host side of the MSI setup.  Anyways I'm afraid I don't have
time to investigate this further.

> The fact that gma500 is touching those MSI
> registers in PCI config space manually is worrying. Did you test if
> MSI works after resume if you remove the save/restore of
> PSB_PCIx_MSI_ADDR_LOC and PSB_PCIx_MSI_DATA_LOC?

Yes I did try removing those save/restores and that did not help.

Note that this patch does get rid of them.

>>> On Poulsbo I can see
>>> interrupts not getting handled during suspend/resume even with this
>>> patch applied.
>>
>> "during" ?  I guess you mean _after_ a suspend/resume ?
> 
> Yes. I get: irq 16: nobody cared (try booting with the "irqpoll" option).
> But perhaps the system is just too slow to respond.
> 
>>
>> I have been refactoring the backlight (detection) code on
>> x86/acpi devices. See:
>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=for-next
>>
>> As you can see there are also some drm driver changes involved for
>> all the (non virtual) drm/kms drivers used on x86/acpi laptops.
>>
>> I am working on also making matching changes (*) to the gma500 code,
>> which is why I scrounged up the Packard Bell Dot SC I'm testing this on.
> 
> I'll have a look.
> 
>>
>> So all the fixes in this series are somewhat of a distraction of what
>> I'm actually trying to acomplish.
> 
> Fair enough, let's not focus too much on the details here. I can take
> this patch as is so you can continue work on the backlight code.
> Sounds good?

Yes if you can take this patch as is that would be great.

Note I have commit/push rights to all the drm-* repositories myself
too. So if you prefer you can just give your Acked-by or Reviewed-by
and then I can push things out myself.

>> I have also scrounged up a Sony Vaio VPCX11S1E which has an Atom
>> Z540 with PSB graphics. I have yet to test on that one though...
> 
> If you do, bring lots of patience. Those systems are very slow. You
> can literally sip on coffee while waiting for the cursor to move :)

Hehe, I'll survive :)

Regards,

Hans




>> *) For wip code see:
>>
>> https://github.com/jwrdegoede/linux-sunxi/commits/main
>>
>> and specifically:
>>
>> https://github.com/jwrdegoede/linux-sunxi/commit/97a1dbbd320b0bdbacf935e52f786e8185005298
>>
>> which unifies the backlight handling between all 3 different
>> SoC types supported by the gma500 code resulting in a nice cleanup.
>>
>>
>>
>>
>>
>>>> 2. After fixing 1. IRQs still do not work on a Packard Bell Dot SC (Intel
>>>>    Atom N2600, cedarview) netbook.
>>>>
>>>>    Cederview uses MSI interrupts and it seems that the BIOS re-configures
>>>>    things back to normal APIC based interrupts during S3 suspend. There is
>>>>    some MSI PCI-config registers save/restore code which tries to deal with
>>>>    this, but on the Packard Bell Dot SC this is not sufficient to restore
>>>>    MSI IRQ functionality after a suspend/resume.
>>>>
>>>>    Replace the PCI-config registers save/restore with pci_disable_msi() on
>>>>    suspend + pci_enable_msi() on resume. Fixing e.g. gnome-shell hanging.
>>>>
>>>> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
>>>> ---
>>>>  drivers/gpu/drm/gma500/cdv_device.c      |  4 +---
>>>>  drivers/gpu/drm/gma500/oaktrail_device.c |  5 +----
>>>>  drivers/gpu/drm/gma500/power.c           |  8 +-------
>>>>  drivers/gpu/drm/gma500/psb_drv.c         |  2 +-
>>>>  drivers/gpu/drm/gma500/psb_drv.h         |  5 +----
>>>>  drivers/gpu/drm/gma500/psb_irq.c         | 15 ++++++++++++---
>>>>  drivers/gpu/drm/gma500/psb_irq.h         |  2 +-
>>>>  7 files changed, 18 insertions(+), 23 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/gma500/cdv_device.c b/drivers/gpu/drm/gma500/cdv_device.c
>>>> index dd32b484dd82..ce96234f3df2 100644
>>>> --- a/drivers/gpu/drm/gma500/cdv_device.c
>>>> +++ b/drivers/gpu/drm/gma500/cdv_device.c
>>>> @@ -581,11 +581,9 @@ static const struct psb_offset cdv_regmap[2] = {
>>>>  static int cdv_chip_setup(struct drm_device *dev)
>>>>  {
>>>>         struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
>>>> -       struct pci_dev *pdev = to_pci_dev(dev->dev);
>>>>         INIT_WORK(&dev_priv->hotplug_work, cdv_hotplug_work_func);
>>>>
>>>> -       if (pci_enable_msi(pdev))
>>>> -               dev_warn(dev->dev, "Enabling MSI failed!\n");
>>>> +       dev_priv->use_msi = true;
>>>>         dev_priv->regmap = cdv_regmap;
>>>>         gma_get_core_freq(dev);
>>>>         psb_intel_opregion_init(dev);
>>>> diff --git a/drivers/gpu/drm/gma500/oaktrail_device.c b/drivers/gpu/drm/gma500/oaktrail_device.c
>>>> index 5923a9c89312..f90e628cb482 100644
>>>> --- a/drivers/gpu/drm/gma500/oaktrail_device.c
>>>> +++ b/drivers/gpu/drm/gma500/oaktrail_device.c
>>>> @@ -501,12 +501,9 @@ static const struct psb_offset oaktrail_regmap[2] = {
>>>>  static int oaktrail_chip_setup(struct drm_device *dev)
>>>>  {
>>>>         struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
>>>> -       struct pci_dev *pdev = to_pci_dev(dev->dev);
>>>>         int ret;
>>>>
>>>> -       if (pci_enable_msi(pdev))
>>>> -               dev_warn(dev->dev, "Enabling MSI failed!\n");
>>>> -
>>>> +       dev_priv->use_msi = true;
>>>>         dev_priv->regmap = oaktrail_regmap;
>>>>
>>>>         ret = mid_chip_setup(dev);
>>>> diff --git a/drivers/gpu/drm/gma500/power.c b/drivers/gpu/drm/gma500/power.c
>>>> index b91de6d36e41..66873085d450 100644
>>>> --- a/drivers/gpu/drm/gma500/power.c
>>>> +++ b/drivers/gpu/drm/gma500/power.c
>>>> @@ -139,8 +139,6 @@ static void gma_suspend_pci(struct pci_dev *pdev)
>>>>         dev_priv->regs.saveBSM = bsm;
>>>>         pci_read_config_dword(pdev, 0xFC, &vbt);
>>>>         dev_priv->regs.saveVBT = vbt;
>>>> -       pci_read_config_dword(pdev, PSB_PCIx_MSI_ADDR_LOC, &dev_priv->msi_addr);
>>>> -       pci_read_config_dword(pdev, PSB_PCIx_MSI_DATA_LOC, &dev_priv->msi_data);
>>>>
>>>>         pci_disable_device(pdev);
>>>>         pci_set_power_state(pdev, PCI_D3hot);
>>>> @@ -168,9 +166,6 @@ static bool gma_resume_pci(struct pci_dev *pdev)
>>>>         pci_restore_state(pdev);
>>>>         pci_write_config_dword(pdev, 0x5c, dev_priv->regs.saveBSM);
>>>>         pci_write_config_dword(pdev, 0xFC, dev_priv->regs.saveVBT);
>>>> -       /* restoring MSI address and data in PCIx space */
>>>> -       pci_write_config_dword(pdev, PSB_PCIx_MSI_ADDR_LOC, dev_priv->msi_addr);
>>>> -       pci_write_config_dword(pdev, PSB_PCIx_MSI_DATA_LOC, dev_priv->msi_data);
>>>>         ret = pci_enable_device(pdev);
>>>>
>>>>         if (ret != 0)
>>>> @@ -223,8 +218,7 @@ int gma_power_resume(struct device *_dev)
>>>>         mutex_lock(&power_mutex);
>>>>         gma_resume_pci(pdev);
>>>>         gma_resume_display(pdev);
>>>> -       gma_irq_preinstall(dev);
>>>> -       gma_irq_postinstall(dev);
>>>> +       gma_irq_install(dev);
>>>>         mutex_unlock(&power_mutex);
>>>>         return 0;
>>>>  }
>>>> diff --git a/drivers/gpu/drm/gma500/psb_drv.c b/drivers/gpu/drm/gma500/psb_drv.c
>>>> index 1d8744f3e702..54e756b48606 100644
>>>> --- a/drivers/gpu/drm/gma500/psb_drv.c
>>>> +++ b/drivers/gpu/drm/gma500/psb_drv.c
>>>> @@ -383,7 +383,7 @@ static int psb_driver_load(struct drm_device *dev, unsigned long flags)
>>>>         PSB_WVDC32(0xFFFFFFFF, PSB_INT_MASK_R);
>>>>         spin_unlock_irqrestore(&dev_priv->irqmask_lock, irqflags);
>>>>
>>>> -       gma_irq_install(dev, pdev->irq);
>>>> +       gma_irq_install(dev);
>>>>
>>>>         dev->max_vblank_count = 0xffffff; /* only 24 bits of frame count */
>>>>
>>>> diff --git a/drivers/gpu/drm/gma500/psb_drv.h b/drivers/gpu/drm/gma500/psb_drv.h
>>>> index 0ea3d23575f3..731cc356c07a 100644
>>>> --- a/drivers/gpu/drm/gma500/psb_drv.h
>>>> +++ b/drivers/gpu/drm/gma500/psb_drv.h
>>>> @@ -490,6 +490,7 @@ struct drm_psb_private {
>>>>         int rpm_enabled;
>>>>
>>>>         /* MID specific */
>>>> +       bool use_msi;
>>>>         bool has_gct;
>>>>         struct oaktrail_gct_data gct_data;
>>>>
>>>> @@ -499,10 +500,6 @@ struct drm_psb_private {
>>>>         /* Register state */
>>>>         struct psb_save_area regs;
>>>>
>>>> -       /* MSI reg save */
>>>> -       uint32_t msi_addr;
>>>> -       uint32_t msi_data;
>>>> -
>>>>         /* Hotplug handling */
>>>>         struct work_struct hotplug_work;
>>>>
>>>> diff --git a/drivers/gpu/drm/gma500/psb_irq.c b/drivers/gpu/drm/gma500/psb_irq.c
>>>> index e6e6d61bbeab..038f18ed0a95 100644
>>>> --- a/drivers/gpu/drm/gma500/psb_irq.c
>>>> +++ b/drivers/gpu/drm/gma500/psb_irq.c
>>>> @@ -316,17 +316,24 @@ void gma_irq_postinstall(struct drm_device *dev)
>>>>         spin_unlock_irqrestore(&dev_priv->irqmask_lock, irqflags);
>>>>  }
>>>>
>>>> -int gma_irq_install(struct drm_device *dev, unsigned int irq)
>>>> +int gma_irq_install(struct drm_device *dev)
>>>>  {
>>>> +       struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
>>>> +       struct pci_dev *pdev = to_pci_dev(dev->dev);
>>>>         int ret;
>>>>
>>>> -       if (irq == IRQ_NOTCONNECTED)
>>>> +       if (dev_priv->use_msi && pci_enable_msi(pdev)) {
>>>> +               dev_warn(dev->dev, "Enabling MSI failed!\n");
>>>> +               dev_priv->use_msi = false;
>>>> +       }
>>>> +
>>>> +       if (pdev->irq == IRQ_NOTCONNECTED)
>>>>                 return -ENOTCONN;
>>>>
>>>>         gma_irq_preinstall(dev);
>>>>
>>>>         /* PCI devices require shared interrupts. */
>>>> -       ret = request_irq(irq, gma_irq_handler, IRQF_SHARED, dev->driver->name, dev);
>>>> +       ret = request_irq(pdev->irq, gma_irq_handler, IRQF_SHARED, dev->driver->name, dev);
>>>>         if (ret)
>>>>                 return ret;
>>>>
>>>> @@ -369,6 +376,8 @@ void gma_irq_uninstall(struct drm_device *dev)
>>>>         spin_unlock_irqrestore(&dev_priv->irqmask_lock, irqflags);
>>>>
>>>>         free_irq(pdev->irq, dev);
>>>> +       if (dev_priv->use_msi)
>>>> +               pci_disable_msi(pdev);
>>>>  }
>>>>
>>>>  int gma_crtc_enable_vblank(struct drm_crtc *crtc)
>>>> diff --git a/drivers/gpu/drm/gma500/psb_irq.h b/drivers/gpu/drm/gma500/psb_irq.h
>>>> index b51e395194ff..7648f69824a5 100644
>>>> --- a/drivers/gpu/drm/gma500/psb_irq.h
>>>> +++ b/drivers/gpu/drm/gma500/psb_irq.h
>>>> @@ -17,7 +17,7 @@ struct drm_device;
>>>>
>>>>  void gma_irq_preinstall(struct drm_device *dev);
>>>>  void gma_irq_postinstall(struct drm_device *dev);
>>>> -int  gma_irq_install(struct drm_device *dev, unsigned int irq);
>>>> +int  gma_irq_install(struct drm_device *dev);
>>>>  void gma_irq_uninstall(struct drm_device *dev);
>>>>
>>>>  int  gma_crtc_enable_vblank(struct drm_crtc *crtc);
>>>> --
>>>> 2.37.2
>>>>
>>>
>>
> 




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