RE: [PATCH v3] drm/i915/display: Fix the 12 BPC bits for PIPE_MISC reg

["Shankar, Uma" <uma.shankar@intel.com>]

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf Of Shankar,
> Uma
> Sent: Wednesday, August 11, 2021 11:39 AM
> To: Nautiyal, Ankit K <ankit.k.nautiyal@intel.com>; intel-gfx@lists.freedesktop.org
> Cc: Zanoni, Paulo R <paulo.r.zanoni@intel.com>; ville.syrjala@linux.intel.com;
> daniel.vetter@ffwll.ch; jani.nikula@linux.intel.com;
> joonas.lahtinen@linux.intel.com; Vivi, Rodrigo <rodrigo.vivi@intel.com>;
> stable@vger.kernel.org
> Subject: Re: [Intel-gfx] [PATCH v3] drm/i915/display: Fix the 12 BPC bits for
> PIPE_MISC reg
> 

Change pushed to drm-intel-next. Thanks for the patch.

Regards,
Uma Shankar
> 
> > -----Original Message-----
> > From: Nautiyal, Ankit K <ankit.k.nautiyal@intel.com>
> > Sent: Wednesday, August 11, 2021 10:49 AM
> > To: intel-gfx@lists.freedesktop.org
> > Cc: Shankar, Uma <uma.shankar@intel.com>; Zanoni, Paulo R
> > <paulo.r.zanoni@intel.com>; ville.syrjala@linux.intel.com;
> > daniel.vetter@ffwll.ch; jani.nikula@linux.intel.com;
> > joonas.lahtinen@linux.intel.com; Vivi, Rodrigo
> > <rodrigo.vivi@intel.com>; stable@vger.kernel.org; Nautiyal, Ankit K
> > <ankit.k.nautiyal@intel.com>
> > Subject: [PATCH v3] drm/i915/display: Fix the 12 BPC bits for
> > PIPE_MISC reg
> >
> > Till DISPLAY12 the PIPE_MISC bits 5-7 are used to set the Dithering
> > BPC, with valid values of 6, 8, 10 BPC.
> > For ADLP+ these bits are used to set the PORT OUTPUT BPC, with valid
> > values of: 6, 8, 10, 12 BPC, and need to be programmed whether dithering is
> enabled or not.
> >
> > This patch:
> > -corrects the bits 5-7 for PIPE MISC register for 12 BPC.
> > -renames the bits and mask to have generic names for these bits for
> > dithering bpc and port output bpc.
> >
> > v3: Added a note for MIPI DSI which uses the PIPE_MISC for readout for pipe_bpp.
> > (Uma Shankar)
> >
> > v2: Added 'display' to the subject and fixes tag. (Uma Shankar)
> >
> 
> Looks Good to me.
> Reviewed-by: Uma Shankar <uma.shankar@intel.com>
> 
> > Fixes: 756f85cffef2 ("drm/i915/bdw: Broadwell has PIPEMISC")
> > Cc: Paulo Zanoni <paulo.r.zanoni@intel.com> (v1)
> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: Jani Nikula <jani.nikula@linux.intel.com>
> > Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > Cc: intel-gfx@lists.freedesktop.org
> > Cc: <stable@vger.kernel.org> # v3.13+
> >
> > Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display.c | 34 ++++++++++++++------
> >  drivers/gpu/drm/i915/i915_reg.h              | 16 ++++++---
> >  2 files changed, 35 insertions(+), 15 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > b/drivers/gpu/drm/i915/display/intel_display.c
> > index b25c596f6f7e..a257e5dc381c 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -5838,16 +5838,18 @@ static void bdw_set_pipemisc(const struct
> > intel_crtc_state *crtc_state)
> >
> >  	switch (crtc_state->pipe_bpp) {
> >  	case 18:
> > -		val |= PIPEMISC_DITHER_6_BPC;
> > +		val |= PIPEMISC_6_BPC;
> >  		break;
> >  	case 24:
> > -		val |= PIPEMISC_DITHER_8_BPC;
> > +		val |= PIPEMISC_8_BPC;
> >  		break;
> >  	case 30:
> > -		val |= PIPEMISC_DITHER_10_BPC;
> > +		val |= PIPEMISC_10_BPC;
> >  		break;
> >  	case 36:
> > -		val |= PIPEMISC_DITHER_12_BPC;
> > +		/* Port output 12BPC defined for ADLP+ */
> > +		if (DISPLAY_VER(dev_priv) > 12)
> > +			val |= PIPEMISC_12_BPC_ADLP;
> >  		break;
> >  	default:
> >  		MISSING_CASE(crtc_state->pipe_bpp);
> > @@ -5900,15 +5902,27 @@ int bdw_get_pipemisc_bpp(struct intel_crtc
> > *crtc)
> >
> >  	tmp = intel_de_read(dev_priv, PIPEMISC(crtc->pipe));
> >
> > -	switch (tmp & PIPEMISC_DITHER_BPC_MASK) {
> > -	case PIPEMISC_DITHER_6_BPC:
> > +	switch (tmp & PIPEMISC_BPC_MASK) {
> > +	case PIPEMISC_6_BPC:
> >  		return 18;
> > -	case PIPEMISC_DITHER_8_BPC:
> > +	case PIPEMISC_8_BPC:
> >  		return 24;
> > -	case PIPEMISC_DITHER_10_BPC:
> > +	case PIPEMISC_10_BPC:
> >  		return 30;
> > -	case PIPEMISC_DITHER_12_BPC:
> > -		return 36;
> > +	/*
> > +	 * PORT OUTPUT 12 BPC defined for ADLP+.
> > +	 *
> > +	 * TODO:
> > +	 * For previous platforms with DSI interface, bits 5:7
> > +	 * are used for storing pipe_bpp irrespective of dithering.
> > +	 * Since the value of 12 BPC is not defined for these bits
> > +	 * on older platforms, need to find a workaround for 12 BPC
> > +	 * MIPI DSI HW readout.
> > +	 */
> > +	case PIPEMISC_12_BPC_ADLP:
> > +		if (DISPLAY_VER(dev_priv) > 12)
> > +			return 36;
> > +		fallthrough;
> >  	default:
> >  		MISSING_CASE(tmp);
> >  		return 0;
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h
> > b/drivers/gpu/drm/i915/i915_reg.h index 167eaa87501b..664970f2bc62
> > 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -6203,11 +6203,17 @@ enum {
> >  #define   PIPEMISC_HDR_MODE_PRECISION	(1 << 23) /* icl+ */
> >  #define   PIPEMISC_OUTPUT_COLORSPACE_YUV  (1 << 11)
> >  #define   PIPEMISC_PIXEL_ROUNDING_TRUNC	REG_BIT(8) /* tgl+ */
> > -#define   PIPEMISC_DITHER_BPC_MASK	(7 << 5)
> > -#define   PIPEMISC_DITHER_8_BPC		(0 << 5)
> > -#define   PIPEMISC_DITHER_10_BPC	(1 << 5)
> > -#define   PIPEMISC_DITHER_6_BPC		(2 << 5)
> > -#define   PIPEMISC_DITHER_12_BPC	(3 << 5)
> > +/*
> > + * For Display < 13, Bits 5-7 of PIPE MISC represent DITHER BPC with
> > + * valid values of: 6, 8, 10 BPC.
> > + * ADLP+, the bits 5-7 represent PORT OUTPUT BPC with valid values of:
> > + * 6, 8, 10, 12 BPC.
> > + */
> > +#define   PIPEMISC_BPC_MASK		(7 << 5)
> > +#define   PIPEMISC_8_BPC		(0 << 5)
> > +#define   PIPEMISC_10_BPC		(1 << 5)
> > +#define   PIPEMISC_6_BPC		(2 << 5)
> > +#define   PIPEMISC_12_BPC_ADLP		(4 << 5) /* adlp+ */
> >  #define   PIPEMISC_DITHER_ENABLE	(1 << 4)
> >  #define   PIPEMISC_DITHER_TYPE_MASK	(3 << 2)
> >  #define   PIPEMISC_DITHER_TYPE_SP	(0 << 2)
> > --
> > 2.25.1