linux-kernel - Re: [Intel-gfx] [PATCH 5/7] drm/i915: Make DP prepare/commit consistent with DP dpms

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Date:	Thu, 3 Nov 2011 13:00:11 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Keith Packard <keithp@...thp.com>
Cc:	intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 5/7] drm/i915: Make DP prepare/commit
 consistent with DP dpms

On Tue,  1 Nov 2011 23:20:28 -0700
Keith Packard <keithp@...thp.com> wrote:

> Make sure the sequence of operations in all three functions makes
> sense:
> 
>  1) The backlight must be off unless the screen is running
>  2) The link must be running to turn the eDP panel on/off
>  3) The CPU eDP PLL must be running until everything is off

A few comments on this one (also, is it strictly required to fix your
bug)?

> Signed-off-by: Keith Packard <keithp@...thp.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c |   22 +++++++++++++---------
>  1 files changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index d6c6608..6be6a04 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1234,17 +1234,18 @@ static void intel_dp_prepare(struct drm_encoder *encoder)
>  {
>  	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
>  
> +	ironlake_edp_backlight_off(intel_dp);
> +	ironlake_edp_panel_off(intel_dp);
> +
>  	/* Wake up the sink first */
>  	ironlake_edp_panel_vdd_on(intel_dp);
>  	intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> +	intel_dp_link_down(intel_dp);
>  	ironlake_edp_panel_vdd_off(intel_dp, false);
>  
>  	/* Make sure the panel is off before trying to
>  	 * change the mode
>  	 */
> -	ironlake_edp_backlight_off(intel_dp);
> -	intel_dp_link_down(intel_dp);
> -	ironlake_edp_panel_off(intel_dp);
>  }

Ok so you're making sure the panel has power to down the link, I think
that's fine.

>  static void intel_dp_commit(struct drm_encoder *encoder)
> @@ -1276,16 +1277,20 @@ intel_dp_dpms(struct drm_encoder *encoder, int mode)
>  	uint32_t dp_reg = I915_READ(intel_dp->output_reg);
>  
>  	if (mode != DRM_MODE_DPMS_ON) {
> +		ironlake_edp_backlight_off(intel_dp);
> +		ironlake_edp_panel_off(intel_dp);
> +
>  		ironlake_edp_panel_vdd_on(intel_dp);
> -		if (is_edp(intel_dp))
> -			ironlake_edp_backlight_off(intel_dp);
>  		intel_dp_sink_dpms(intel_dp, mode);
>  		intel_dp_link_down(intel_dp);
> -		ironlake_edp_panel_off(intel_dp);
> -		if (is_edp(intel_dp) && !is_pch_edp(intel_dp))
> -			ironlake_edp_pll_off(encoder);
>  		ironlake_edp_panel_vdd_off(intel_dp, false);
> +
> +		if (is_cpu_edp(intel_dp))
> +			ironlake_edp_pll_off(encoder);


But here it looks like you're shutting it off, then downing the link?
Should this be reordered?

-- 
Jesse Barnes, Intel Open Source Technology Center

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