[Intel-gfx] [PATCH v3] drm/i915: Check HAS_PCH_NOP when install or reset dispaly IRQ

[Wang, Elaine]

Hi Jani, Ville,

Any comment about the "PCH_NOP" vs "num_pipes == 0"?

Thanks,
Elaine
> On Thu, 15 Dec 2016, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> > On Mon, Dec 12, 2016 at 02:57:44PM +0800, Wang Elaine wrote:
> >> From: Elaine Wang <elaine.wang at intel.com>
> >>
> >> Some platforms don't have display. To avoid accessing the 
> >> non-existent registers, check HAS_PCH_NOP before invoking display 
> >> IRQ install or reset function.
> >>
> >> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> >> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> >> Signed-off-by: Elaine Wang <elaine.wang at intel.com>
> >> ---
> >>  drivers/gpu/drm/i915/i915_irq.c | 10 +++++++---
> >>  1 file changed, 7 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/i915_irq.c 
> >> b/drivers/gpu/drm/i915/i915_irq.c index 0b119b9..369a038 100644
> >> --- a/drivers/gpu/drm/i915/i915_irq.c
> >> +++ b/drivers/gpu/drm/i915/i915_irq.c
> >> @@ -2990,8 +2990,10 @@ static void gen8_irq_reset(struct drm_device
> *dev)
> >>
> POWER_DOMAIN_PIPE(pipe)))
> >>  			GEN8_IRQ_RESET_NDX(DE_PIPE, pipe);
> >>
> >> -	GEN5_IRQ_RESET(GEN8_DE_PORT_);
> >> -	GEN5_IRQ_RESET(GEN8_DE_MISC_);
> >> +	if (!HAS_PCH_NOP(dev_priv)) {
> >> +		GEN5_IRQ_RESET(GEN8_DE_PORT_);
> >> +		GEN5_IRQ_RESET(GEN8_DE_MISC_);
> >> +	}
> >
> > Hmm. These are north side registers so looking at PCH_NOP feels 
> > questionable.
> 
> Indeed, num_pipes == 0 isn't exactly the same thing as HAS_PCH_NOP.
> 
> Jani.

I thought HAS_PCH_NOP had same meaning as num_pipes == 0 because I saw following code in i915_drv.c. Is there any exception?

https://cgit.freedesktop.org/drm-intel/tree/drivers/gpu/drm/i915/i915_drv.c?h=drm-intel-nightly#n145
static void intel_detect_pch(struct drm_i915_private *dev_priv) {
	struct pci_dev *pch = NULL;

	/* In all current cases, num_pipes is equivalent to the PCH_NOP setting
	 * (which really amounts to a PCH but no South Display).
	 */
	if (INTEL_INFO(dev_priv)->num_pipes == 0) {
		dev_priv->pch_type = PCH_NOP;
		return;
	}

Thanks,
Elaine
> 
> 
> >
> >>  	GEN5_IRQ_RESET(GEN8_PCU_);
> >>
> >>  	if (HAS_PCH_SPLIT(dev_priv))
> >> @@ -3414,7 +3416,9 @@ static int gen8_irq_postinstall(struct 
> >> drm_device
> *dev)
> >>  		ibx_irq_pre_postinstall(dev);
> >>
> >>  	gen8_gt_irq_postinstall(dev_priv);
> >> -	gen8_de_irq_postinstall(dev_priv);
> >> +
> >> +	if (!HAS_PCH_NOP(dev_priv))
> >> +		gen8_de_irq_postinstall(dev_priv);
> >>
> >>  	if (HAS_PCH_SPLIT(dev_priv))
> >>  		ibx_irq_postinstall(dev);
> >> --
> >> 1.9.1
> 
> --
> Jani Nikula, Intel Open Source Technology Center
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