Re: [Intel-gfx] [PATCH v3] drm/i915/display: Do not allow DC3CO if PSR SF is enabled

["Gupta, Anshuman" <anshuman.gupta@intel.com>]

> -----Original Message-----
> From: Mun, Gwan-gyeong <gwan-gyeong.mun@intel.com>
> Sent: Tuesday, February 23, 2021 3:00 AM
> To: intel-gfx@lists.freedesktop.org
> Cc: Gupta, Anshuman <anshuman.gupta@intel.com>; Souza, Jose
> <jose.souza@intel.com>
> Subject: [PATCH v3] drm/i915/display: Do not allow DC3CO if PSR SF is enabled
> 
> Even though GEN12+ HW supports PSR + DC3CO, DMC's HW DC3CO exit
> mechanism has an issue with using of Selective Fecth and PSR2 manual tracking.
> And as some GEN12+ platforms (RKL, ADL-S) don't support PSR2 HW tracking,
> Selective Fetch will be enabled by default on that platforms.
> Therefore if the system enables PSR Selective Fetch / PSR manual tracking, it
> does not allow DC3CO dc state, in that case.
> 
> When this DC3CO exit issue is addressed while PSR Selective Fetch is enabled,
> this restriction should be removed.
> 
> v2: Address Jose's review comment.
>   - Fix typo
>   - Move check routine of DC3CO ability to
>     tgl_dc3co_exitline_compute_config()
> v3: Change the check routine of enablement of psr2 sel fetch. (Jose)
> 
> Cc: José Roberto de Souza <jose.souza@intel.com>
> Cc: Anshuman Gupta <anshuman.gupta@intel.com>
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_psr.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> b/drivers/gpu/drm/i915/display/intel_psr.c
> index 7c6e561f86c1..cd434285e3b7 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -654,6 +654,13 @@ tgl_dc3co_exitline_compute_config(struct intel_dp
> *intel_dp,
>  	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
>  	u32 exit_scanlines;
> 
> +	/*
> +	 * DMC's DC3CO exit mechanism has an issue with Selective Fecth
> +	 * TODO: when the issue is addressed, this restriction should be
> removed.
> +	 */
Earlier when PSR2 H/W tracking was enabled, DC3CO exit and frame updates works on it's own
Supported by DE engine and DMC firmware, but with selective fetch enable  as it disables the PSR2 H/W
Tracking. It requires to get sequence of DC3CO exit while PSR2 H/W tracking disabled.
Br,
Anshuman Gupta.  
> +	if (crtc_state->enable_psr2_sel_fetch)
> +		return;
> +
>  	if (!(dev_priv->csr.allowed_dc_mask & DC_STATE_EN_DC3CO))
>  		return;
> 
> --
> 2.30.0

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