Re: [PATCH 2/2] nouveau: Acknowledge HPD irq in handler, not bottom half

[Ben Skeggs <bskeggs@redhat.com>]

On Wed, 2010-11-10 at 17:25 -0500, Andrew Lutomirski wrote:
> On Wed, Nov 10, 2010 at 5:10 PM, Ben Skeggs <bskeggs@redhat.com> wrote:
> > On Wed, 2010-11-10 at 16:32 -0500, Andy Lutomirski wrote:
> >> The old code generated an interrupt storm bad enough to completely
> >> take down my system.
> >>
> >> This only fixes the bits that are defined nouveau_regs.h.  Newer hardware
> >> uses another register that isn't described, and I don't have that hardware
> >> to test.
> > Thanks for looking at this.  I'll take a closer look at the problem
> > today and see what I can come up with too, that'll work with the newer
> > hardware too.
> 
> It should be as simple as adding an hpd1 field to the hpd_state and
> making exactly the same change.  (It would be nice to put the register
> definitions into nouveau_regs.h as well -- I didn't really want to
> muck around with a bunch of magic numbers that I can't test.)
Yes, it is.  I can confirm the problem on another card, but it doesn't
actually cause any crashes here.  If you can rework the patch to support
the newer chips too, that'd be great.

As for magic numbers, the register names for those regs are wrong
anyway.  The joy of reverse-engineering the support.  It doesn't really
matter if you want to stick to them or go back to "magic" numbers.

Ben.

> 
> I tried writing 0xffffffff to the display IRQ control in the handler
> to explicitly acknowledge the IRQ, but either I did it wrong or it had
> no effect.
> 
> I imagine that this explains the unreproducible crashes I had on F13 as well.
> 
> --Andy
> 
> >
> > Ben.
> >>
> >> Signed-off-by: Andy Lutomirski <luto@mit.edu>
> >> Cc: <stable@kernel.org>
> >> ---
> >>  drivers/gpu/drm/nouveau/nouveau_drv.h  |    5 +++++
> >>  drivers/gpu/drm/nouveau/nouveau_irq.c  |    1 +
> >>  drivers/gpu/drm/nouveau/nv50_display.c |   17 +++++++++++++----
> >>  3 files changed, 19 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
> >> index b1be617..b6c62cc 100644
> >> --- a/drivers/gpu/drm/nouveau/nouveau_drv.h
> >> +++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
> >> @@ -531,6 +531,11 @@ struct drm_nouveau_private {
> >>       struct work_struct irq_work;
> >>       struct work_struct hpd_work;
> >>
> >> +     struct {
> >> +             spinlock_t lock;
> >> +             uint32_t hpd0_bits;
> >> +     } hpd_state;
> >> +
> >>       struct list_head vbl_waiting;
> >>
> >>       struct {
> >> diff --git a/drivers/gpu/drm/nouveau/nouveau_irq.c b/drivers/gpu/drm/nouveau/nouveau_irq.c
> >> index 794b0ee..b62a601 100644
> >> --- a/drivers/gpu/drm/nouveau/nouveau_irq.c
> >> +++ b/drivers/gpu/drm/nouveau/nouveau_irq.c
> >> @@ -52,6 +52,7 @@ nouveau_irq_preinstall(struct drm_device *dev)
> >>       if (dev_priv->card_type >= NV_50) {
> >>               INIT_WORK(&dev_priv->irq_work, nv50_display_irq_handler_bh);
> >>               INIT_WORK(&dev_priv->hpd_work, nv50_display_irq_hotplug_bh);
> >> +             spin_lock_init(&dev_priv->hpd_state.lock);
> >>               INIT_LIST_HEAD(&dev_priv->vbl_waiting);
> >>       }
> >>  }
> >> diff --git a/drivers/gpu/drm/nouveau/nv50_display.c b/drivers/gpu/drm/nouveau/nv50_display.c
> >> index 83a7d27..0df08e3 100644
> >> --- a/drivers/gpu/drm/nouveau/nv50_display.c
> >> +++ b/drivers/gpu/drm/nouveau/nv50_display.c
> >> @@ -1014,7 +1014,12 @@ nv50_display_irq_hotplug_bh(struct work_struct *work)
> >>       uint32_t unplug_mask, plug_mask, change_mask;
> >>       uint32_t hpd0, hpd1 = 0;
> >>
> >> -     hpd0 = nv_rd32(dev, NV50_PCONNECTOR_HOTPLUG_CTRL) & nv_rd32(dev, NV50_PCONNECTOR_HOTPLUG_INTR);
> >> +     spin_lock_irq(&dev_priv->hpd_state.lock);
> >> +     hpd0 = dev_priv->hpd_state.hpd0_bits;
> >> +     dev_priv->hpd_state.hpd0_bits = 0;
> >> +     spin_unlock_irq(&dev_priv->hpd_state.lock);
> >> +
> >> +     hpd0 &= nv_rd32(dev, NV50_PCONNECTOR_HOTPLUG_INTR);
> >>       if (dev_priv->chipset >= 0x90)
> >>               hpd1 = nv_rd32(dev, 0xe074) & nv_rd32(dev, 0xe070);
> >>
> >> @@ -1058,7 +1063,6 @@ nv50_display_irq_hotplug_bh(struct work_struct *work)
> >>                       helper->dpms(connector->encoder, DRM_MODE_DPMS_OFF);
> >>       }
> >>
> >> -     nv_wr32(dev, NV50_PCONNECTOR_HOTPLUG_CTRL, nv_rd32(dev, NV50_PCONNECTOR_HOTPLUG_CTRL));
> >>       if (dev_priv->chipset >= 0x90)
> >>               nv_wr32(dev, 0xe074, nv_rd32(dev, 0xe074));
> >>
> >> @@ -1072,8 +1076,13 @@ nv50_display_irq_handler(struct drm_device *dev)
> >>       uint32_t delayed = 0;
> >>
> >>       if (nv_rd32(dev, NV50_PMC_INTR_0) & NV50_PMC_INTR_0_HOTPLUG) {
> >> -             if (!work_pending(&dev_priv->hpd_work))
> >> -                     queue_work(dev_priv->wq, &dev_priv->hpd_work);
> >> +             uint32_t hpd0_bits = nv_rd32(dev, NV50_PCONNECTOR_HOTPLUG_CTRL);
> >> +             nv_wr32(dev, NV50_PCONNECTOR_HOTPLUG_CTRL, hpd0_bits);
> >> +             spin_lock(&dev_priv->hpd_state.lock);
> >> +             dev_priv->hpd_state.hpd0_bits |= hpd0_bits;
> >> +             spin_unlock(&dev_priv->hpd_state.lock);
> >> +
> >> +             queue_work(dev_priv->wq, &dev_priv->hpd_work);
> >>       }
> >>
> >>       while (nv_rd32(dev, NV50_PMC_INTR_0) & NV50_PMC_INTR_0_DISPLAY) {
> >
> >
> >