ACK/Cmnt: [PATCH 1/1] UBUNTU: SAUCE: Revert "drm/i915: Fix hotplug irq ack on i965/g4x"

[Stefan Bader]

On 12.03.19 18:30, Kai-Heng Feng wrote:
> BugLink: https://bugs.launchpad.net/bugs/1819486
> 
> This reverts commit 2f2a7c6570455b1d49161f14ecd1438b3504deab.
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
Acked-by: Stefan Bader <stefan.bader at canonical.com>
> ---

Sounds like another case of either something missing or not yet fixed up. But
any way a pit of doom lurking.

-Stefan

>  drivers/gpu/drm/i915/i915_irq.c | 32 ++------------------------------
>  1 file changed, 2 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 38d6d1bfe14e..f6d496c09d3f 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1956,38 +1956,10 @@ static void valleyview_pipestat_irq_handler(struct drm_i915_private *dev_priv,
>  
>  static u32 i9xx_hpd_irq_ack(struct drm_i915_private *dev_priv)
>  {
> -	u32 hotplug_status = 0, hotplug_status_mask;
> -	int i;
> -
> -	if (IS_G4X(dev_priv) ||
> -	    IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
> -		hotplug_status_mask = HOTPLUG_INT_STATUS_G4X |
> -			DP_AUX_CHANNEL_MASK_INT_STATUS_G4X;
> -	else
> -		hotplug_status_mask = HOTPLUG_INT_STATUS_I915;
> +	u32 hotplug_status = I915_READ(PORT_HOTPLUG_STAT);
>  
> -	/*
> -	 * We absolutely have to clear all the pending interrupt
> -	 * bits in PORT_HOTPLUG_STAT. Otherwise the ISR port
> -	 * interrupt bit won't have an edge, and the i965/g4x
> -	 * edge triggered IIR will not notice that an interrupt
> -	 * is still pending. We can't use PORT_HOTPLUG_EN to
> -	 * guarantee the edge as the act of toggling the enable
> -	 * bits can itself generate a new hotplug interrupt :(
> -	 */
> -	for (i = 0; i < 10; i++) {
> -		u32 tmp = I915_READ(PORT_HOTPLUG_STAT) & hotplug_status_mask;
> -
> -		if (tmp == 0)
> -			return hotplug_status;
> -
> -		hotplug_status |= tmp;
> +	if (hotplug_status)
>  		I915_WRITE(PORT_HOTPLUG_STAT, hotplug_status);
> -	}
> -
> -	WARN_ONCE(1,
> -		  "PORT_HOTPLUG_STAT did not clear (0x%08x)\n",
> -		  I915_READ(PORT_HOTPLUG_STAT));
>  
>  	return hotplug_status;
>  }
> 


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