[PATCH v1, 1/1] drm/mediatek: add lut diff flag for new gamma hardware support

[yongqiang.niu]

On Tue, 2022-04-26 at 09:58 +0800, CK Hu wrote:
> Hi, Yongqiang:
> 
> On Wed, 2022-04-20 at 21:06 +0800, Yongqiang Niu wrote:
> > From: Yongqiang Niu <yongqiang.niu at mediatek.corp-partner.google.com
> > >
> > 
> > mt8183 gamma module usage is different with before soc,
> > gamma odd(index start from 0) lut value set to hardware
> > register should be
> > the difference of current lut value with last lut value.
> > 
> > gamma function support both increase and decrease lut.
> 
> How to set decrease lut?
> 
> Original lut:
> 12 10 8 6 4 2
> 
> Does diff lut look like this?
> 12 [2] 8 [2] 4 [2]
> 
yes

> How does hardware know that this is increase lut or decrease lut?

gamma register 0x20 , bit 2, 
if this bit set to 1, hardware will know lut is decrease.
this bit default is 0, that means lut is increase

> 
> > chrome os app set increase lut normally.
> > 
> > for increase lut example, chrome os user space set lut
> > like this(only r chanel for example):
> > 2 4 6 8 10 12.
> > 1) mt8183 gamma driver should set the gamma lut to hardware
> > register like this:
> > 2 [2] 6 [8] 10 [2]
> 
> 2 [2] 6 [2] 10 [2]
> 
> > the value with [] is the difference value
> > 2) gamma hardware will restore the lut when apply gamma
> > function to display
> 
> I don't know why do you mention the 'restore', any modification is
> related to this?
> 
that means gamma
hardware process display data with original lut
> > 
> > Signed-off-by: Yongqiang Niu <
> > yongqiang.niu at mediatek.corp-partner.google.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_disp_aal.c   |  4 ++-
> >  drivers/gpu/drm/mediatek/mtk_disp_drv.h   |  2 +-
> >  drivers/gpu/drm/mediatek/mtk_disp_gamma.c | 34 +++++++++++++++++++
> > ----
> >  3 files changed, 32 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_disp_aal.c
> > b/drivers/gpu/drm/mediatek/mtk_disp_aal.c
> > index f46d4ab73d6a..e6378b074a17 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_disp_aal.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_disp_aal.c
> > @@ -23,6 +23,7 @@
> >  
> >  struct mtk_disp_aal_data {
> >  	bool has_gamma;
> > +	bool lut_diff;
> >  };
> >  
> >  /**
> > @@ -66,7 +67,7 @@ void mtk_aal_gamma_set(struct device *dev, struct
> > drm_crtc_state *state)
> >  	struct mtk_disp_aal *aal = dev_get_drvdata(dev);
> >  
> >  	if (aal->data && aal->data->has_gamma)
> > -		mtk_gamma_set_common(aal->regs, state);
> > +		mtk_gamma_set_common(aal->regs, state, aal->data-
> > > lut_diff);
> 
> gamma in aal does not support diff lut, so this would make things
> simple.
> 
> mtk_gamma_set_common(aal->regs, state, false);

fix next version
> 
> Regards,
> CK
> 
> >  }
> >  
> >  void mtk_aal_start(struct device *dev)
> > @@ -148,6 +149,7 @@ static int mtk_disp_aal_remove(struct
> > platform_device *pdev)
> >  
> >  static const struct mtk_disp_aal_data mt8173_aal_driver_data = {
> >  	.has_gamma = true,
> > +	.lut_diff = false,
> >  };
> >  
> >  static const struct of_device_id mtk_disp_aal_driver_dt_match[] =
> > {
> > diff --git a/drivers/gpu/drm/mediatek/mtk_disp_drv.h
> > b/drivers/gpu/drm/mediatek/mtk_disp_drv.h
> > index 86c3068894b1..3380651c6707 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_disp_drv.h
> > +++ b/drivers/gpu/drm/mediatek/mtk_disp_drv.h
> > @@ -51,7 +51,7 @@ void mtk_gamma_config(struct device *dev,
> > unsigned
> > int w,
> >  		      unsigned int h, unsigned int vrefresh,
> >  		      unsigned int bpc, struct cmdq_pkt *cmdq_pkt);
> >  void mtk_gamma_set(struct device *dev, struct drm_crtc_state
> > *state);
> > -void mtk_gamma_set_common(void __iomem *regs, struct
> > drm_crtc_state
> > *state);
> > +void mtk_gamma_set_common(void __iomem *regs, struct
> > drm_crtc_state
> > *state, bool lut_diff);
> >  void mtk_gamma_start(struct device *dev);
> >  void mtk_gamma_stop(struct device *dev);
> >  
> > diff --git a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> > b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> > index 3a5815ab4079..fec2e9a5b60d 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> > @@ -27,6 +27,7 @@
> >  
> >  struct mtk_disp_gamma_data {
> >  	bool has_dither;
> > +	bool lut_diff;
> >  };
> >  
> >  /*
> > @@ -53,12 +54,13 @@ void mtk_gamma_clk_disable(struct device *dev)
> >  	clk_disable_unprepare(gamma->clk);
> >  }
> >  
> > -void mtk_gamma_set_common(void __iomem *regs, struct
> > drm_crtc_state
> > *state)
> > +void mtk_gamma_set_common(void __iomem *regs, struct
> > drm_crtc_state
> > *state, bool lut_diff)
> >  {
> >  	unsigned int i, reg;
> >  	struct drm_color_lut *lut;
> >  	void __iomem *lut_base;
> >  	u32 word;
> > +	u32 diff[3] = {0};
> >  
> >  	if (state->gamma_lut) {
> >  		reg = readl(regs + DISP_GAMMA_CFG);
> > @@ -67,9 +69,20 @@ void mtk_gamma_set_common(void __iomem *regs,
> > struct drm_crtc_state *state)
> >  		lut_base = regs + DISP_GAMMA_LUT;
> >  		lut = (struct drm_color_lut *)state->gamma_lut->data;
> >  		for (i = 0; i < MTK_LUT_SIZE; i++) {
> > -			word = (((lut[i].red >> 6) & LUT_10BIT_MASK) <<
> > 20) +
> > -				(((lut[i].green >> 6) & LUT_10BIT_MASK)
> > << 10) +
> > -				((lut[i].blue >> 6) & LUT_10BIT_MASK);
> > +
> > +			if (!lut_diff || (i % 2 == 0)) {
> > +				word = (((lut[i].red >> 6) &
> > LUT_10BIT_MASK) << 20) +
> > +					(((lut[i].green >> 6) &
> > LUT_10BIT_MASK) << 10) +
> > +					((lut[i].blue >> 6) &
> > LUT_10BIT_MASK);
> > +			} else {
> > +				diff[0] = abs((lut[i].red >> 6) -
> > (lut[i - 1].red >> 6));
> > +				diff[1] = abs((lut[i].green >> 6) -
> > (lut[i - 1].green >> 6));
> > +				diff[2] = abs((lut[i].blue >> 6) -
> > (lut[i - 1].blue >> 6));
> > +
> > +				word = ((diff[0] & LUT_10BIT_MASK) <<
> > 20) +
> > +					((diff[1] & LUT_10BIT_MASK) <<
> > 10) +
> > +					(diff[2] & LUT_10BIT_MASK);
> > +			}
> >  			writel(word, (lut_base + i * 4));
> >  		}
> >  	}
> > @@ -78,8 +91,12 @@ void mtk_gamma_set_common(void __iomem *regs,
> > struct drm_crtc_state *state)
> >  void mtk_gamma_set(struct device *dev, struct drm_crtc_state
> > *state)
> >  {
> >  	struct mtk_disp_gamma *gamma = dev_get_drvdata(dev);
> > +	bool lut_diff = false;
> > +
> > +	if (gamma->data)
> > +		lut_diff = gamma->data->lut_diff;
> >  
> > -	mtk_gamma_set_common(gamma->regs, state);
> > +	mtk_gamma_set_common(gamma->regs, state, lut_diff);
> >  }
> >  
> >  void mtk_gamma_config(struct device *dev, unsigned int w,
> > @@ -176,10 +193,15 @@ static const struct mtk_disp_gamma_data
> > mt8173_gamma_driver_data = {
> >  	.has_dither = true,
> >  };
> >  
> > +static const struct mtk_disp_gamma_data mt8183_gamma_driver_data =
> > {
> > +	.lut_diff = true,
> > +};
> > +
> >  static const struct of_device_id mtk_disp_gamma_driver_dt_match[]
> > =
> > {
> >  	{ .compatible = "mediatek,mt8173-disp-gamma",
> >  	  .data = &mt8173_gamma_driver_data},
> > -	{ .compatible = "mediatek,mt8183-disp-gamma"},
> > +	{ .compatible = "mediatek,mt8183-disp-gamma",
> > +	  .data = &mt8183_gamma_driver_data},
> >  	{},
> >  };
> >  MODULE_DEVICE_TABLE(of, mtk_disp_gamma_driver_dt_match);
> 
>