Re: [PATCH v2 2/3] drm/i915: Enable IPS with only sprite plane visible too, v2.

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

On Mon, Nov 20, 2017 at 01:23:36PM +0100, Maarten Lankhorst wrote:
> This comment predates atomic, and I think with the way we currently
> track IPS, it's safe to enable this for the case we switch too.
> 
> Changes since v1:
> - Keep IPS enabled when switching planes.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 0b9ba415839a..09817bc6f9a8 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -6237,13 +6237,8 @@ static bool hsw_compute_ips_config(struct intel_crtc_state *pipe_config)
>  	if (pipe_config->ips_force_disable)
>  		return false;
>  
> -	/*
> -	 * FIXME IPS should be fine as long as one plane is
> -	 * enabled, but in practice it seems to have problems
> -	 * when going from primary only to sprite only and vice
> -	 * versa.
> -	 */
> -	if (!(pipe_config->active_planes & BIT(PLANE_PRIMARY)))
> +	/* IPS should be fine as long as one plane is enabled. */

Maybe "... at least one plane is enabled." to make it less vague?

> +	if (hweight32(pipe_config->active_planes & ~BIT(PLANE_CURSOR)) != 1)

I keep wondering if popcnt is cheaper than is_power_of_2()? If it is,
maybe someone should actually make is_power_of_2() use popcnt...

>  		return false;
>  
>  	/* HSW can handle pixel rate up to cdclk? */
> -- 
> 2.15.0
> 
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-- 
Ville Syrjälä
Intel OTC
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