[Intel-gfx] [PATCH] Revert "drm/i915: re-order if/else ladder for hpd_irq_setup"

[Lucas De Marchi]

On Mon, Nov 30, 2020 at 04:19:54PM +0200, Ville Syrjälä wrote:
>On Fri, Nov 27, 2020 at 08:52:29PM -0800, Lucas De Marchi wrote:
>> On Fri, Nov 27, 2020 at 02:57:48PM +0000, Chris Wilson wrote:
>> >We now use ilk_hpd_irq_setup for all GMCH platforms that do not have
>> >hotplug. These are early gen3 and gen2 devices that now explode on boot
>> >as they try to access non-existent registers.
>>
>> humn... true, my bad. But I don't think a revert is the right fix. It
>> would be much better if we would not be setting up the hpd setup
>> function at all for platforms that do not have hotplug. I think a
>> separate early check for I915_HAS_HOTPLUG() would be deserved.
>
>I think it generally leads to much less convoluted logic when we keep
>gmch vs. rest separate. So I'm confused as to what we're even trying
>to achieve here?

1) Stop trying to setup hotplug in a platform that doesn't have hotplug
was the main focus. Later it would be better to move some of these
hotplug to display/  as they are clearly display related and account for
a great portion of i915_irq.c.

I left the I915_HAS_HOTPLUG() in the middle by
mistake, it should had been an earlier call.

2) semi-related is the move of GMCH to the middle and I guess this is
what you're complaining here. I find it's cumbersome to have it
separate as we go and extend these checks for newer platforms. Almost
everywhere we settled on having last platform first in the if/else
ladders - this makes it much more clear on how/where to add a new
platform.

Lucas De Marchi

>
>>
>> Lucas De Marchi
>>
>> >
>> >Fixes: 794d61a19090 ("drm/i915: re-order if/else ladder for hpd_irq_setup")
>> >Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>> >Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>> >Cc: José Roberto de Souza <jose.souza at intel.com>
>> >Cc: Jani Nikula <jani.nikula at linux.intel.com>
>>
>>
>> >---
>> > drivers/gpu/drm/i915/i915_irq.c | 27 +++++++++++++++------------
>> > 1 file changed, 15 insertions(+), 12 deletions(-)
>> >
>> >diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
>> >index dc6febc63f1c..c80eeac53952 100644
>> >--- a/drivers/gpu/drm/i915/i915_irq.c
>> >+++ b/drivers/gpu/drm/i915/i915_irq.c
>> >@@ -4242,18 +4242,21 @@ void intel_irq_init(struct drm_i915_private *dev_priv)
>> > 	 */
>> > 	dev_priv->hotplug.hpd_short_storm_enabled = !HAS_DP_MST(dev_priv);
>> >
>> >-	if (HAS_PCH_DG1(dev_priv))
>> >-		dev_priv->display.hpd_irq_setup = dg1_hpd_irq_setup;
>> >-	else if (INTEL_GEN(dev_priv) >= 11)
>> >-		dev_priv->display.hpd_irq_setup = gen11_hpd_irq_setup;
>> >-	else if (IS_GEN9_LP(dev_priv))
>> >-		dev_priv->display.hpd_irq_setup = bxt_hpd_irq_setup;
>> >-	else if (INTEL_PCH_TYPE(dev_priv) >= PCH_SPT)
>> >-		dev_priv->display.hpd_irq_setup = spt_hpd_irq_setup;
>> >-	else if (HAS_GMCH(dev_priv) && I915_HAS_HOTPLUG(dev_priv))
>> >-		dev_priv->display.hpd_irq_setup = i915_hpd_irq_setup;
>> >-	else
>> >-		dev_priv->display.hpd_irq_setup = ilk_hpd_irq_setup;
>> >+	if (HAS_GMCH(dev_priv)) {
>> >+		if (I915_HAS_HOTPLUG(dev_priv))
>> >+			dev_priv->display.hpd_irq_setup = i915_hpd_irq_setup;
>> >+	} else {
>> >+		if (HAS_PCH_DG1(dev_priv))
>> >+			dev_priv->display.hpd_irq_setup = dg1_hpd_irq_setup;
>> >+		else if (INTEL_GEN(dev_priv) >= 11)
>> >+			dev_priv->display.hpd_irq_setup = gen11_hpd_irq_setup;
>> >+		else if (IS_GEN9_LP(dev_priv))
>> >+			dev_priv->display.hpd_irq_setup = bxt_hpd_irq_setup;
>> >+		else if (INTEL_PCH_TYPE(dev_priv) >= PCH_SPT)
>> >+			dev_priv->display.hpd_irq_setup = spt_hpd_irq_setup;
>> >+		else
>> >+			dev_priv->display.hpd_irq_setup = ilk_hpd_irq_setup;
>> >+	}
>> > }
>> >
>> > /**
>> >--
>> >2.20.1
>> >
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>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
>-- 
>Ville Syrjälä
>Intel