Re: [PATCH] drm/i915: Fix PSR programming

Jani Nikula
2014-03-05T09:31:39Z

On Wed, 05 Mar 2014, Ben Widawsky <benjamin.widawsky@intel.com> wrote:
> | has a higher precedence than ?. Therefore, the calculation doesn't do
> at all what you would expect. Thanks to Ken for convincing me that this
> was indeed the issue. Send me back to C programmer school, please.
>
> I'm sort of surprised PSR was continuing to work for people. It should
> be broken IMO (and it was broken for me, but I had assumed it never
> worked).
>
> Regression from:
> commit ed8546ac1f99b850879f07b1e9b06b42fb0a36d9
> Author: Ben Widawsky <benjamin.widawsky@intel.com>
> Date: Mon Nov 4 22:45:05 2013 -0800
>
> drm/i915/bdw: Support eDP PSR
>
> I am pretty certain PSR is disabled by default, so no CC stable.

I think I'll pick this up for -fixes, with CC stable, as it also breaks
Haswell PSR.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> Cc: Rodrigo Vivi <rodrigo.vivi@gmail.com>
> Cc: Kenneth Graunke <kenneth.w.graunke@intel.com>
> Cc: Art Runyan <arthur.j.runyan@intel.com>
> Reported-by: "Kumar, Kiran S" <kiran.s.kumar@intel.com>
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> ---
> 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 c512d78..2c0ceb4 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1723,7 +1723,7 @@ static void intel_edp_psr_enable_source(struct intel_dp *intel_dp)
> val |= EDP_PSR_LINK_DISABLE;
>
> I915_WRITE(EDP_PSR_CTL(dev), val |
> - IS_BROADWELL(dev) ? 0 : link_entry_time |
> + (IS_BROADWELL(dev) ? 0 : link_entry_time) |
> max_sleep_time << EDP_PSR_MAX_SLEEP_TIME_SHIFT |
> idle_frames << EDP_PSR_IDLE_FRAME_SHIFT |
> EDP_PSR_ENABLE);
> --
> 1.9.0
>
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--
Jani Nikula, Intel Open Source Technology Center