[Intel-gfx] [PATCH] drm/i915: add hotplug activation period to hotplug update mask

[Ville Syrjälä]

On Wed, Oct 21, 2015 at 05:22:43PM +0300, Jani Nikula wrote:
> commit 0706f17c307b056ff6f1848320ba82d76945a6ff
> Author: Egbert Eich <eich at suse.de>
> Date:   Wed Sep 23 16:15:27 2015 +0200
> 
>     drm/i915: Avoid race of intel_crt_detect_hotplug() with HPD interrupt, v2
> 
> added a check with WARN to ensure only bits within the mask are
> enabled. Turns out that doesn't hold for G4X, which spits out:
> 
> [    2.641439] ------------[ cut here ]------------
> [    2.641444] WARNING: CPU: 0 PID: 1 at drivers/gpu/drm/i915/i915_irq.c:182 i915_hotplug_interrupt_update_locked+0x45/0x83()
> [    2.641446] WARN_ON(bits & ~mask)
> etc.
> 
> Add CRT_HOTPLUG_ACTIVATION_PERIOD_64 to the mask to fix the warning.
> 
> Reported-by: Oleksij Rempel <linux at rempel-privat.de>
> References: https://bugzilla.kernel.org/show_bug.cgi?id=104991
> Fixes: 0706f17c307b ("drm/i915: Avoid race of intel_crt_detect_hotplug() with HPD interrupt, v2")
> Cc: Egbert Eich <eich at suse.de>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 7f91f74961f4..5b9f63d4318b 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -4236,9 +4236,10 @@ static void i915_hpd_irq_setup(struct drm_device *dev)
>  
>  	/* Ignore TV since it's buggy */
>  	i915_hotplug_interrupt_update_locked(dev_priv,
> -				      (HOTPLUG_INT_EN_MASK
> -				       | CRT_HOTPLUG_VOLTAGE_COMPARE_MASK),
> -				      hotplug_en);
> +					     HOTPLUG_INT_EN_MASK |
> +					     CRT_HOTPLUG_VOLTAGE_COMPARE_MASK |
> +					     CRT_HOTPLUG_ACTIVATION_PERIOD_64,
> +					     hotplug_en);

Or maybe just ~CRT_HOTPLUG_FORCE_DETECT ?

>  }
>  
>  static irqreturn_t i965_irq_handler(int irq, void *arg)
> -- 
> 2.1.4
> 
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-- 
Ville Syrjälä
Intel OTC