On Thu, Feb 10, 2022 at 10:52:23AM -0800, José Roberto de Souza wrote:
> PSR2 workaround required when mode has delayed vblank.
>
> BSpec: 52890
> BSpec: 49421
> Cc: Jouni Högander <jouni.hogan...@intel.com>
> Signed-off-by: José Roberto de Souza <jose.so...@intel.com>
I think we better implement it in a more generic way.
BSpec 71580 formulates this workaround more precisely:
"
If any low power watermark is disabled because the package C state
has too much latency for the size of Vblank and PSR1 or PSR2 is enabled,
set the register bit for this pipe (listing below) to 1 to disable a
PSR optimization to override to the maximum watermark.
Clear the bit if the size of Vblank does not require low power watermarks to be
disabled
or PSR* is disabled."
Pipe A 0x46430 bit 23
Pipe B 0x46430 bit 24
Pipe C 0x46430 bit 25
Pipe D 0x46430 bit 31
TRANS_SET_CONTEXT_LATENCY is used to delay the vblank"
Almost we must ensure that one:
Vblank time >= MAX(framestart delay + package C state latency + watermark 0
time + pipe scaler pre-fill time + DSC pre-fill time,
PSR2 vblank time, SDP vblank time)
Line time >= PSR2 line time
I'm currently working on the latter one. I have suggestion that one I finish
with calculations required for this formula, I can provide some api for this
patch in order to check if PSR can be enabled and workaround has to be applied.
Stan
> ---
> drivers/gpu/drm/i915/display/intel_psr.c | 40 ++++++++++++++++++++++--
> drivers/gpu/drm/i915/i915_reg.h | 13 +++++---
> 2 files changed, 46 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c
> b/drivers/gpu/drm/i915/display/intel_psr.c
> index 72bd8d3261e0c..2e0b092f4b6be 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -1063,7 +1063,23 @@ static void intel_psr_activate(struct intel_dp
> *intel_dp)
> intel_dp->psr.active = true;
> }
>
> -static void intel_psr_enable_source(struct intel_dp *intel_dp)
> +static u32 wa_16013835468_bit_get(struct intel_dp *intel_dp)
> +{
> + switch (intel_dp->psr.pipe) {
> + case PIPE_A:
> + return LATENCY_REPORTING_REMOVED_PIPE_A;
> + case PIPE_B:
> + return LATENCY_REPORTING_REMOVED_PIPE_B;
> + case PIPE_C:
> + return LATENCY_REPORTING_REMOVED_PIPE_C;
> + default:
> + MISSING_CASE(intel_dp->psr.pipe);
> + return 0;
> + }
> +}
> +
> +static void intel_psr_enable_source(struct intel_dp *intel_dp,
> + const struct intel_crtc_state *crtc_state)
> {
> struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> enum transcoder cpu_transcoder = intel_dp->psr.transcoder;
> @@ -1133,6 +1149,20 @@ static void intel_psr_enable_source(struct intel_dp
> *intel_dp)
> if (IS_ALDERLAKE_P(dev_priv))
> intel_de_rmw(dev_priv, CLKGATE_DIS_MISC, 0,
> CLKGATE_DIS_MISC_DMASC_GATING_DIS);
> +
> + /* Wa_16013835468:tgl[b0+], dg1 */
> + if (IS_TGL_DISPLAY_STEP(dev_priv, STEP_B0, STEP_FOREVER) ||
> + IS_DG1(dev_priv)) {
> + u16 vtotal, vblank;
> +
> + vtotal = crtc_state->uapi.adjusted_mode.crtc_vtotal -
> + crtc_state->uapi.adjusted_mode.crtc_vdisplay;
> + vblank = crtc_state->uapi.adjusted_mode.crtc_vblank_end
> -
> +
> crtc_state->uapi.adjusted_mode.crtc_vblank_start;
> + if (vblank > vtotal)
> + intel_de_rmw(dev_priv, GEN8_CHICKEN_DCPR_1, 0,
> + wa_16013835468_bit_get(intel_dp));
> + }
> }
> }
>
> @@ -1198,7 +1228,7 @@ static void intel_psr_enable_locked(struct intel_dp
> *intel_dp,
> intel_write_dp_vsc_sdp(encoder, crtc_state, &crtc_state->psr_vsc);
> intel_snps_phy_update_psr_power_state(dev_priv, phy, true);
> intel_psr_enable_sink(intel_dp);
> - intel_psr_enable_source(intel_dp);
> + intel_psr_enable_source(intel_dp, crtc_state);
> intel_dp->psr.enabled = true;
> intel_dp->psr.paused = false;
>
> @@ -1297,6 +1327,12 @@ static void intel_psr_disable_locked(struct intel_dp
> *intel_dp)
> if (IS_ALDERLAKE_P(dev_priv))
> intel_de_rmw(dev_priv, CLKGATE_DIS_MISC,
> CLKGATE_DIS_MISC_DMASC_GATING_DIS, 0);
> +
> + /* Wa_16013835468:tgl[b0+], dg1 */
> + if (IS_TGL_DISPLAY_STEP(dev_priv, STEP_B0, STEP_FOREVER) ||
> + IS_DG1(dev_priv))
> + intel_de_rmw(dev_priv, GEN8_CHICKEN_DCPR_1,
> + wa_16013835468_bit_get(intel_dp), 0);
> }
>
> intel_snps_phy_update_psr_power_state(dev_priv, phy, false);
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 87c92314ee269..1cd4056400b63 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -6040,11 +6040,14 @@
> #define HSW_NDE_RSTWRN_OPT _MMIO(0x46408)
> #define RESET_PCH_HANDSHAKE_ENABLE (1 << 4)
>
> -#define GEN8_CHICKEN_DCPR_1 _MMIO(0x46430)
> -#define SKL_SELECT_ALTERNATE_DC_EXIT REG_BIT(30)
> -#define ICL_DELAY_PMRSP REG_BIT(22)
> -#define DISABLE_FLR_SRC REG_BIT(15)
> -#define MASK_WAKEMEM REG_BIT(13)
> +#define GEN8_CHICKEN_DCPR_1 _MMIO(0x46430)
> +#define SKL_SELECT_ALTERNATE_DC_EXIT REG_BIT(30)
> +#define LATENCY_REPORTING_REMOVED_PIPE_C REG_BIT(25)
> +#define LATENCY_REPORTING_REMOVED_PIPE_B REG_BIT(24)
> +#define LATENCY_REPORTING_REMOVED_PIPE_A REG_BIT(23)
> +#define ICL_DELAY_PMRSP REG_BIT(22)
> +#define DISABLE_FLR_SRC REG_BIT(15)
> +#define MASK_WAKEMEM REG_BIT(13)
>
> #define GEN11_CHICKEN_DCPR_2 _MMIO(0x46434)
> #define DCPR_MASK_MAXLATENCY_MEMUP_CLR REG_BIT(27)
> --
> 2.35.1
>
