Re: [PATCH 6/7] drm/i915: vlv: fix mapping of pipestat enable to status bits

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Feb 04, 2014 at 09:35:50PM +0200, Imre Deak wrote:
> At least on VLV we can't get at the pipestat status bits by simply right
> shifting the corresponding enable bits. The mapping between enable and
> status bits for the sprite0,1 flip done and the PSR events don't follow
> this rule, so we need to map them separately.
> 
> The PSR enable for pipe A is DPFLIPSTAT[22], but I haven't added support
> for this, since there is no user of it atm. Until support is added WARN
> if someone tries to enable PSR interrupts, or tries to enable the same
> (1 << 6) bit on pipe B, which MBZ.
> 
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 36 +++++++++++++++++++++++++++++++++++-
>  drivers/gpu/drm/i915/i915_reg.h |  3 +++
>  2 files changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index ec56a70..eea5398 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -471,9 +471,29 @@ done:
>  	return ret;
>  }
>  
> +static void set_pipestat_enable_bit(u32 status_mask, u32 status_bit,
> +				    u32 enable_bit, u32 *enable_mask)
> +{
> +	if (status_mask & status_bit)
> +		*enable_mask |= enable_bit;
> +	else
> +		*enable_mask &= ~enable_bit;
> +}
> +
>  static u32 pipestat_to_enable_mask(struct drm_device *dev, u32 status_mask)
>  {
> -	return status_mask << 16;
> +	u32 enable_mask = status_mask << 16;
> +
> +	if (!IS_VALLEYVIEW(dev))
> +		return enable_mask;
> +
> +	enable_mask &= ~PIPE_FIFO_UNDERRUN_STATUS;
> +	set_pipestat_enable_bit(status_mask, SPRITE1_FLIP_DONE_INT_STATUS_VLV,
> +				SPRITE1_FLIP_DONE_INT_EN_VLV, &enable_mask);
> +	set_pipestat_enable_bit(enable_mask, SPRITE0_FLIP_DONE_INT_STATUS_VLV,
> +				SPRITE0_FLIP_DONE_INT_EN_VLV, &enable_mask);

This feels a bit subtle to me. Maybe do it in a bit more straightforward
way? Eg.:

enable_mask &= ~(PIPE_FIFO_UNDERRUN_STATUS |
		 SPRITE0_FLIP_DONE_INT_EN_VLV |
		 SPRITE1_FLIP_DONE_INT_EN_VLV);
if (status_mask & SPRITE0_FLIP_DONE_INT_STATUS_VLV)
	enable_mask |= SPRITE0_FLIP_DONE_INT_EN_VLV;
if (status_mask & SPRITE1_FLIP_DONE_INT_STATUS_VLV)
	enable_mask |= SPRITE1_FLIP_DONE_INT_EN_VLV;

> +
> +	return enable_mask;
>  }
>  
>  void
> @@ -489,6 +509,13 @@ i915_enable_pipestat(drm_i915_private_t *dev_priv, enum pipe pipe,
>  	if (WARN_ON_ONCE(status_mask & ~PIPESTAT_INT_STATUS_MASK))
>  		return;
>  
> +	/*
> +	 * On pipe A we don't support the PSR interrupt yet, on pipe B the
> +	 * same bit MBZ.
> +	 */
> +	if (WARN_ON_ONCE(status_mask & PIPE_A_PSR_STATUS_VLV))
> +		return;

Won't this break the BLC interrupt on gen3/4?

> +
>  	enable_mask = pipestat_to_enable_mask(dev_priv->dev, status_mask);
>  	if ((pipestat & enable_mask) == enable_mask)
>  		return;
> @@ -512,6 +539,13 @@ i915_disable_pipestat(drm_i915_private_t *dev_priv, enum pipe pipe,
>  	if (WARN_ON_ONCE(status_mask & ~PIPESTAT_INT_STATUS_MASK))
>  		return;
>  
> +	/*
> +	 * On pipe A we don't support the PSR interrupt yet, on pipe B the
> +	 * same bit MBZ.
> +	 */
> +	if (WARN_ON_ONCE(status_mask & PIPE_A_PSR_STATUS_VLV))
> +		return;
> +
>  	enable_mask = pipestat_to_enable_mask(dev_priv->dev, status_mask);
>  	if ((pipestat & enable_mask) == 0)
>  		return;
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 599c7f6..c998c4f 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -3240,6 +3240,7 @@
>  #define   PIPE_LEGACY_BLC_EVENT_ENABLE		(1UL<<22)
>  #define   PIPE_ODD_FIELD_INTERRUPT_ENABLE	(1UL<<21)
>  #define   PIPE_EVEN_FIELD_INTERRUPT_ENABLE	(1UL<<20)
> +#define   PIPE_B_PSR_INTERRUPT_ENABLE_VLV	(1UL<<19)
>  #define   PIPE_HOTPLUG_TV_INTERRUPT_ENABLE	(1UL<<18) /* pre-965 */
>  #define   PIPE_START_VBLANK_INTERRUPT_ENABLE	(1UL<<18) /* 965 or later */
>  #define   PIPE_VBLANK_INTERRUPT_ENABLE		(1UL<<17)
> @@ -3256,8 +3257,10 @@
>  #define   PIPE_DISPLAY_LINE_COMPARE_STATUS	(1UL<<8)
>  #define   PIPE_DPST_EVENT_STATUS		(1UL<<7)
>  #define   PIPE_LEGACY_BLC_EVENT_STATUS		(1UL<<6)
> +#define   PIPE_A_PSR_STATUS_VLV			(1UL<<6)
>  #define   PIPE_ODD_FIELD_INTERRUPT_STATUS	(1UL<<5)
>  #define   PIPE_EVEN_FIELD_INTERRUPT_STATUS	(1UL<<4)
> +#define   PIPE_B_PSR_STATUS_VLV			(1UL<<3)
>  #define   PIPE_HOTPLUG_TV_INTERRUPT_STATUS	(1UL<<2) /* pre-965 */
>  #define   PIPE_START_VBLANK_INTERRUPT_STATUS	(1UL<<2) /* 965 or later */
>  #define   PIPE_VBLANK_INTERRUPT_STATUS		(1UL<<1)
> -- 
> 1.8.4
> 
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-- 
Ville Syrjälä
Intel OTC