[Intel-gfx] [PATCH 1/2] drm/i915: fix the SDE irq dmesg warnings properly

[Ville Syrjälä]

On Wed, Nov 25, 2015 at 04:47:22PM +0200, Jani Nikula wrote:
> We had the "The master control interrupt lied (SDE)!" check and error
> message in place for a long time without any problems, until
> 
> commit aaf5ec2e51ab1d9c5e962b4728a1107ed3ff7a3e
> Author: Sonika Jindal <sonika.jindal at intel.com>
> Date:   Wed Jul 8 17:07:47 2015 +0530
> 
>     drm/i915: Handle HPD when it has actually occurred
> 
> caused the errors to start happening. This was bisected and reported,
> but the error message was silenced in
> 
> commit 97e5ed1111dcc5300a0f59a55248cd243937a8ab
> Author: Daniel Vetter <daniel.vetter at ffwll.ch>
> Date:   Fri Oct 23 10:56:12 2015 +0200
> 
>     drm/i915: shut up gen8+ SDE irq dmesg noise
> 
> shooting the messenger while the debugging for why Sonika's commit
> triggered the errors was still in progress.
> 
> It looks like we need to read and acknowledge the PCH_PORT_HOTPLUG
> register even though the hotplug trigger indicates there isn't a hotplug
> irq to handle.
> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Sonika Jindal <sonika.jindal at intel.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92084
> Fixes: aaf5ec2e51ab ("drm/i915: Handle HPD when it has actually occurred")
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index c8ba94968aaf..982951d3153a 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1825,7 +1825,17 @@ static void ibx_hpd_irq_handler(struct drm_device *dev, u32 hotplug_trigger,
>  	u32 dig_hotplug_reg, pin_mask = 0, long_mask = 0;
>  
>  	dig_hotplug_reg = I915_READ(PCH_PORT_HOTPLUG);
> +	if (!hotplug_trigger) {
> +		u32 mask = PORTA_HOTPLUG_STATUS_MASK |
> +			PORTD_HOTPLUG_STATUS_MASK |
> +			PORTC_HOTPLUG_STATUS_MASK |
> +			PORTB_HOTPLUG_STATUS_MASK;
> +		dig_hotplug_reg &= ~mask;
> +	}
> +
>  	I915_WRITE(PCH_PORT_HOTPLUG, dig_hotplug_reg);
> +	if (!hotplug_trigger)
> +		return;

I would add some kind of comment around these parts to explain that
somehow the PCH doesn't seem to really ack the interrupt to the CPU
unless we touch the hotplug register.

Otherwise (for both patches)
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Also not sure if SKL might need something similar as well...

>  
>  	intel_get_hpd_pins(&pin_mask, &long_mask, hotplug_trigger,
>  			   dig_hotplug_reg, hpd,
> @@ -1840,8 +1850,7 @@ static void ibx_irq_handler(struct drm_device *dev, u32 pch_iir)
>  	int pipe;
>  	u32 hotplug_trigger = pch_iir & SDE_HOTPLUG_MASK;
>  
> -	if (hotplug_trigger)
> -		ibx_hpd_irq_handler(dev, hotplug_trigger, hpd_ibx);
> +	ibx_hpd_irq_handler(dev, hotplug_trigger, hpd_ibx);
>  
>  	if (pch_iir & SDE_AUDIO_POWER_MASK) {
>  		int port = ffs((pch_iir & SDE_AUDIO_POWER_MASK) >>
> @@ -1934,8 +1943,7 @@ static void cpt_irq_handler(struct drm_device *dev, u32 pch_iir)
>  	int pipe;
>  	u32 hotplug_trigger = pch_iir & SDE_HOTPLUG_MASK_CPT;
>  
> -	if (hotplug_trigger)
> -		ibx_hpd_irq_handler(dev, hotplug_trigger, hpd_cpt);
> +	ibx_hpd_irq_handler(dev, hotplug_trigger, hpd_cpt);
>  
>  	if (pch_iir & SDE_AUDIO_POWER_MASK_CPT) {
>  		int port = ffs((pch_iir & SDE_AUDIO_POWER_MASK_CPT) >>
> -- 
> 2.1.4

-- 
Ville Syrjälä
Intel OTC