[Intel-gfx] [PATCH] drm/i915: Disable DC5 before going to DC9

[Imre Deak]

On Wed, Apr 20, 2022 at 03:09:21PM -0400, Rodrigo Vivi wrote:
> According to BSPec:
> 	Sequence to Allow DC9:
> 		1. Follow Sequence to Disallow DC5.
> 
> which is:
> 	Sequence to Disallow DC5 and DC6
> 		Set DC_STATE_EN Dynamic DC State Enable = "Disable".
> 
> I understand that we haven't had any issue so far. But since
> DC9 is a software thing, it is better to disable DC5 before
> to avoid any conflict. And respect the spec to avoid potential
> future issues.
> 
> Cc: Imre Deak <imre.deak at intel.com>
> Cc: Anshuman Gupta <anshuman.gupta at intel.com>
> Cc: Anusha Srivatsa <anusha.srivatsa at intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display_power.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
> index 6a5695008f7c..b3cf5182044f 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_power.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_power.c
> @@ -883,6 +883,9 @@ static void bxt_enable_dc9(struct drm_i915_private *dev_priv)
>  {
>  	assert_can_enable_dc9(dev_priv);
>  
> +	/* Disable DC5 before enabling DC9 */
> +	gen9_set_dc_state(dev_priv, DC_STATE_DISABLE);

For DC9 DMC should be disabled already, along with DC states and other
dependencies like power well 1, etc. That happens in
bxt/icl_display_core_uninit().

> +
>  	drm_dbg_kms(&dev_priv->drm, "Enabling DC9\n");
>  	/*
>  	 * Power sequencer reset is not needed on
> -- 
> 2.34.1
>