[PATCHv2 4/5] drm/i915/histogram: histogram delay counter doesnt reset

[Kandpal, Suraj]

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Arun R
> Murthy
> Sent: Wednesday, August 21, 2024 3:54 PM
> To: intel-gfx at lists.freedesktop.org
> Cc: Murthy, Arun R <arun.r.murthy at intel.com>
> Subject: [PATCHv2 4/5] drm/i915/histogram: histogram delay counter doesnt
> reset
> 
> The delay counter for histogram does not reset and as a result the histogram bin
> never gets updated. Woraround would be to use save and restore histogram

Typo "Workaround"

> register.
> 
> Signed-off-by: Arun R Murthy <arun.r.murthy at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_histogram.c | 17 +++++++++++++++++
> drivers/gpu/drm/i915/display/intel_histogram.h |  1 +
>  2 files changed, 18 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_histogram.c
> b/drivers/gpu/drm/i915/display/intel_histogram.c
> index ad4f75607ccb..189f7ccd6df8 100644
> --- a/drivers/gpu/drm/i915/display/intel_histogram.c
> +++ b/drivers/gpu/drm/i915/display/intel_histogram.c
> @@ -36,6 +36,11 @@ static void intel_histogram_handle_int_work(struct
> work_struct *work)
>  	u32 dpstbin;
>  	int i, try = 0;
> 
> +	/* Wa: 14014889975 */
> +	if (IS_DISPLAY_VER(i915, 12, 13))
> +		intel_de_rmw(i915, DPST_CTL(intel_crtc->pipe),
> +			     DPST_CTL_RESTORE, 0);
> +
>  	/*
>  	 * TODO: PSR to be exited while reading the Histogram data
>  	 * Set DPST_CTL Bin Reg function select to TC @@ -77,6 +82,12 @@
> static void intel_histogram_handle_int_work(struct work_struct *work)
>  			       histogram_event))
>  		drm_err(&i915->drm, "sending HISTOGRAM event failed\n");
> 
> +	/* Wa: 14014889975 */
> +	if (IS_DISPLAY_VER(i915, 12, 13))
> +		/* Write the value read from DPST_CTL to DPST_CTL.Interrupt
> Delay Counter(bit 23:16) */
> +		intel_de_write(i915, DPST_CTL(intel_crtc->pipe),
> intel_de_read(i915,
> +			       DPST_CTL(intel_crtc->pipe)) | DPST_CTL_RESTORE);
> +
>  	/* Enable histogram interrupt */
>  	intel_de_rmw(i915, DPST_GUARD(intel_crtc->pipe),
> DPST_GUARD_HIST_INT_EN,
>  		     DPST_GUARD_HIST_INT_EN);
> @@ -140,6 +151,12 @@ static int intel_histogram_enable(struct intel_crtc
> *intel_crtc)
>  	/* Pipe Dithering should be enabled with GLOBAL_HIST */
>  	intel_histogram_enable_dithering(i915, pipe);
> 
> +	/* Wa: 14014889975 */
> +	if (IS_DISPLAY_VER(i915, 12, 13))
> +		/* Write the value read from DPST_CTL to DPST_CTL.Interrupt
> Delay Counter(bit 23:16) */
> +		intel_de_write(i915, DPST_CTL(intel_crtc->pipe),
> intel_de_read(i915,
> +			       DPST_CTL(intel_crtc->pipe)) | DPST_CTL_RESTORE);
> +

Maybe put all the code in a function with required variables and one extra bool variable that determines
If it is being called when interrupt is being serviced or when histogram is being enabled

wa_14014889975(.., bool enable)
	if (!IS_DISPLAY_VER(i915, 12, 13)) /* I think there is a function that checks if display_ver is not it range to avoid the !
		return 
	if (enable)
		/* Write the value read from DPST_CTL to DPST_CTL.Interrupt
		 Delay Counter(bit 23:16) */
		intel_de_write(i915, DPST_CTL(intel_crtc->pipe),
		intel_de_read(i915,
			       DPST_CTL(intel_crtc->pipe)) | DPST_CTL_RESTORE);	
	Else
		intel_de_rmw(i915, DPST_CTL(intel_crtc->pipe),
			     DPST_CTL_RESTORE, 0);

Also use intel_display instead of i915

Regards,
Suraj Kandpal
 
>  	 * enable DPST_CTL Histogram mode
>  	 * Clear DPST_CTL Bin Reg function select to TC diff --git
> a/drivers/gpu/drm/i915/display/intel_histogram.h
> b/drivers/gpu/drm/i915/display/intel_histogram.h
> index f35ea76719d8..5e24d3c5c28b 100644
> --- a/drivers/gpu/drm/i915/display/intel_histogram.h
> +++ b/drivers/gpu/drm/i915/display/intel_histogram.h
> @@ -20,6 +20,7 @@ enum pipe;
>  #define DPST_CTL_RESTORE				REG_BIT(28)
>  #define DPST_CTL_IE_MODI_TABLE_EN			REG_BIT(27)
>  #define DPST_CTL_HIST_MODE				REG_BIT(24)
> +#define DPST_CTL_GUARDBAND_INTERRUPT_DELAY_CNT
> 	REG_GENMASK(23, 16)
>  #define DPST_CTL_ENHANCEMENT_MODE_MASK
> 	REG_GENMASK(14, 13)
>  #define DPST_CTL_EN_MULTIPLICATIVE
> 	REG_FIELD_PREP(DPST_CTL_ENHANCEMENT_MODE_MASK, 2)
>  #define DPST_CTL_IE_TABLE_VALUE_FORMAT			REG_BIT(15)
> --
> 2.25.1