[Intel-gfx] [PATCH] drm/i915: HSW/BDW PSR Set idle_frames=2 since sometimes it can be off by 1.

[Daniel Vetter]

On Thu, Oct 30, 2014 at 05:35:55AM -0700, Rodrigo Vivi wrote:
> It was identified that in some cases when moving cursor Hardware can do
> mistake with idle_frame count. So Spec is being updated to use
> 2 as minimum idle_frames.
> 
> Reference: https://hsdhsw.intel.com/hsd/haswell_platform/default.aspx#sighting/default.aspx?sighting_id=4394433
> Cc: Arthur Runyan <arthur.j.runyan at intel.com>
> Cc: Jani Nikula <jani.nikula at intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

Since we have full-blown sw frontbuffer tracking: Do we care?

I.e. is the effect of idle_frames = 1 that the hw will go bananas (bad, we
want this patch) or that it might miss a cursor movement (no problem, the
kernel will catch it anyway)?

Cheers, Daniel

> ---
>  drivers/gpu/drm/i915/intel_dp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 47e9d71..8cfbbc2 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -2178,7 +2178,7 @@ static void intel_edp_psr_enable_source(struct intel_dp *intel_dp)
>  	struct drm_device *dev = dig_port->base.base.dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	uint32_t max_sleep_time = 0x1f;
> -	uint32_t idle_frames = 1;
> +	uint32_t idle_frames = 2; /* 2 is the minimum allowed */
>  	uint32_t val = 0x0;
>  	const uint32_t link_entry_time = EDP_PSR_MIN_LINK_ENTRY_TIME_8_LINES;
>  	bool only_standby = false;
> -- 
> 1.9.3
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch