Re: [PATCH] drm/i915/pps: Disable DPLS_GATING around pps sequence

[Jani Nikula <jani.nikula@intel.com>]

On Tue, 16 Apr 2024, Suraj Kandpal <suraj.kandpal@intel.com> wrote:
> Disable bit 29 of SCLKGATE_DIS register around pps sequence
> when we turn panel power on.
>
> --v2
> -Squash two commit together [Jani]
> -Use IS_DISPLAY_VER [Jani]
> -Fix multiline comment [Jani]
>
> Bspec: 49304
> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_pps.c | 12 ++++++++++++
>  drivers/gpu/drm/i915/i915_reg.h          |  4 ++++
>  2 files changed, 16 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_pps.c b/drivers/gpu/drm/i915/display/intel_pps.c
> index 3078dfac7817..2b2cead22a7d 100644
> --- a/drivers/gpu/drm/i915/display/intel_pps.c
> +++ b/drivers/gpu/drm/i915/display/intel_pps.c
> @@ -948,6 +948,14 @@ void intel_pps_on_unlocked(struct intel_dp *intel_dp)
>  		intel_de_posting_read(dev_priv, pp_ctrl_reg);
>  	}
>  
> +	/*
> +	 * WA: 16023567976
> +	 * Disable DPLS gating around power sequence.
> +	 */
> +	if (IS_DISPLAY_VER(dev_priv, 12, 14))
> +		intel_de_rmw(dev_priv, SCLKGATE_DIS,
> +			     DPLS_GATING_DISABLE, 1);
> +
>  	pp |= PANEL_POWER_ON;
>  	if (!IS_IRONLAKE(dev_priv))
>  		pp |= PANEL_POWER_RESET;
> @@ -958,6 +966,10 @@ void intel_pps_on_unlocked(struct intel_dp *intel_dp)
>  	wait_panel_on(intel_dp);
>  	intel_dp->pps.last_power_on = jiffies;
>  
> +	if (IS_DISPLAY_VER(dev_priv, 12, 14))
> +		intel_de_rmw(dev_priv, SCLKGATE_DIS,
> +			     DPLS_GATING_DISABLE, 0);
> +
>  	if (IS_IRONLAKE(dev_priv)) {
>  		pp |= PANEL_POWER_RESET; /* restore panel reset bit */
>  		intel_de_write(dev_priv, pp_ctrl_reg, pp);
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 3f34efcd7d6c..1c2cd6cc254f 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -6250,6 +6250,10 @@ enum skl_power_gate {
>  #define  SFUSE_STRAP_DDIC_DETECTED	(1 << 1)
>  #define  SFUSE_STRAP_DDID_DETECTED	(1 << 0)
>  
> +/* SCLKGATE_DIS */

How is that comment helpful?

Can we find another file under display/ for this register?

BR,
Jani.

> +#define SCLKGATE_DIS			_MMIO(0xc2020)
> +#define  DPLS_GATING_DISABLE		REG_BIT(29)
> +
>  #define WM_MISC				_MMIO(0x45260)
>  #define  WM_MISC_DATA_PARTITION_5_6	(1 << 0)

-- 
Jani Nikula, Intel