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

["Srivatsa, Anusha" <anusha.srivatsa@intel.com>]

> -----Original Message-----
> From: Vivi, Rodrigo <rodrigo.vivi@intel.com>
> Sent: Wednesday, April 20, 2022 12:09 PM
> To: intel-gfx@lists.freedesktop.org
> Cc: Vivi, Rodrigo <rodrigo.vivi@intel.com>; Deak, Imre
> <imre.deak@intel.com>; Gupta, Anshuman <anshuman.gupta@intel.com>;
> Srivatsa, Anusha <anusha.srivatsa@intel.com>
> Subject: [PATCH] drm/i915: Disable DC5 before going to DC9
> 
> 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@intel.com>
> Cc: Anshuman Gupta <anshuman.gupta@intel.com>
> Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@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);

^ We are already checking if DC5 is enabled. If enabled then don't enable DC9. SO the change should be- if driver cannot enableDC9 because DC5 is enabled then go ahead and disable DC5.

Anusha 
> +	/* Disable DC5 before enabling DC9 */
> +	gen9_set_dc_state(dev_priv, DC_STATE_DISABLE);
> +
>  	drm_dbg_kms(&dev_priv->drm, "Enabling DC9\n");
>  	/*
>  	 * Power sequencer reset is not needed on
> --
> 2.34.1