[Intel-gfx] [PATCH] drm/i915: set CDCLK if DPLL0 enabled during resuming from S3

[Damien Lespiau]

On Fri, Aug 28, 2015 at 04:40:34PM +0800, Gary Wang wrote:
> Since BIOS RC 1.4 it would enable CDCLK PLL during BIOS S3 resume, then
> driver needs to set CDCLK to avoid display corruption if DPLL0 enabled.
> 
> References: https://bugs.freedesktop.org/show_bug.cgi?id=91697
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Reviewed-by: Damien Lespiau <damien.lespiau at intel.com>
> Reviewed-by: Cooper Chiou <cooper.chiou at intel.com>
> Reviewed-by: Wei Shun Chang <wei.shun.chang at intel.com>
> Tested-by: Gary Wang <gary.c.wang at intel.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Gavin Hindman <gavin.hindman at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Xiong Y Zhang <xiong.y.zhang at intel.com>
> Signed-off-by: Gary Wang <gary.c.wang at intel.com>

Hum I had not given my r-b tag before this mail, r-b tags cannot be
forged by the patch author but needs to be explicitly given by someone.
In any case:

Reviewed-by: Damien Lespiau <damien.lespiau at intel.com>

We could probably remove the '!?' as this is now the expected behaviour
with recent firmware.

-- 
Damien

> ---
>  drivers/gpu/drm/i915/intel_display.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
>  mode change 100644 => 100755 drivers/gpu/drm/i915/intel_display.c
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> old mode 100644
> new mode 100755
> index f604ce1..617d1d8
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -5707,16 +5707,13 @@ void skl_init_cdclk(struct drm_i915_private *dev_priv)
>  	/* enable PG1 and Misc I/O */
>  	intel_display_power_get(dev_priv, POWER_DOMAIN_PLLS);
>  
> -	/* DPLL0 already enabed !? */
> -	if (I915_READ(LCPLL1_CTL) & LCPLL_PLL_ENABLE) {
> -		DRM_DEBUG_DRIVER("DPLL0 already running\n");
> -		return;
> +	/* DPLL0 not enabed !? */
> +	if (!(I915_READ(LCPLL1_CTL) & LCPLL_PLL_ENABLE)) {
> +		/* enable DPLL0 */
> +		required_vco = skl_cdclk_get_vco(dev_priv->skl_boot_cdclk);
> +		skl_dpll0_enable(dev_priv, required_vco);
>  	}
>  
> -	/* enable DPLL0 */
> -	required_vco = skl_cdclk_get_vco(dev_priv->skl_boot_cdclk);
> -	skl_dpll0_enable(dev_priv, required_vco);
> -
>  	/* set CDCLK to the frequency the BIOS chose */
>  	skl_set_cdclk(dev_priv, dev_priv->skl_boot_cdclk);
>  
> -- 
> 1.9.1
> 
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