[RFC PATCH] drm/sun4i: Implement gamma correction

[Maxime Ripard]

Hi Vasily,

On Wed, Mar 13, 2019 at 07:58:38PM -0700, Vasily Khoruzhick wrote:
> Add support for gamma corretion to sun4i TCON driver. Its LUT has 256
> entries and can be updated only when gamma correction is disabled.
> 
> Signed-off-by: Vasily Khoruzhick <anarsoul at gmail.com>

It's not really clear to me what you expect a comment on?

Maxime

> ---
>  drivers/gpu/drm/sun4i/sun4i_crtc.c | 15 ++++++++++++++
>  drivers/gpu/drm/sun4i/sun4i_tcon.c | 33 ++++++++++++++++++++++++++++++
>  drivers/gpu/drm/sun4i/sun4i_tcon.h | 12 ++++++++++-
>  3 files changed, 59 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun4i_crtc.c b/drivers/gpu/drm/sun4i/sun4i_crtc.c
> index 3eedf335a935..719259d09632 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_crtc.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_crtc.c
> @@ -101,6 +101,20 @@ static void sun4i_crtc_atomic_flush(struct drm_crtc *crtc,
>  			drm_crtc_send_vblank_event(crtc, event);
>  		spin_unlock_irq(&crtc->dev->event_lock);
>  	}
> +
> +	if (crtc->state->color_mgmt_changed) {
> +		if (crtc->state->gamma_lut) {
> +			/* LUT can be only updated when gamma correction is
> +			 * disabled
> +			 */
> +			sun4i_tcon_enable_gamma(scrtc->tcon, false);
> +			sun4i_tcon_load_gamma_lut(scrtc->tcon,
> +						  crtc->state->gamma_lut->data);
> +			sun4i_tcon_enable_gamma(scrtc->tcon, true);
> +		} else
> +			sun4i_tcon_enable_gamma(scrtc->tcon, false);
> +	}
> +
>  }
>  
>  static void sun4i_crtc_atomic_disable(struct drm_crtc *crtc,
> @@ -184,6 +198,7 @@ static const struct drm_crtc_funcs sun4i_crtc_funcs = {
>  	.set_config		= drm_atomic_helper_set_config,
>  	.enable_vblank		= sun4i_crtc_enable_vblank,
>  	.disable_vblank		= sun4i_crtc_disable_vblank,
> +	.gamma_set		= drm_atomic_helper_legacy_gamma_set,
>  };
>  
>  struct sun4i_crtc *sun4i_crtc_init(struct drm_device *drm,
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> index cf45d0f940f9..3f5f9d4f54a6 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -215,6 +215,34 @@ void sun4i_tcon_enable_vblank(struct sun4i_tcon *tcon, bool enable)
>  }
>  EXPORT_SYMBOL(sun4i_tcon_enable_vblank);
>  
> +void sun4i_tcon_load_gamma_lut(struct sun4i_tcon *tcon,
> +			       struct drm_color_lut *lut)
> +{
> +	int i;
> +
> +	for (i = 0; i < SUN4I_TCON_GAMMA_LUT_SIZE; i++) {
> +		u32 r, g, b;
> +
> +		r = drm_color_lut_extract(lut[i].red, 8);
> +		g = drm_color_lut_extract(lut[i].green, 8);
> +		b = drm_color_lut_extract(lut[i].blue, 8);
> +
> +		regmap_write(tcon->regs, SUN4I_TCON_GAMMA_TABLE_REG + 4 * i,
> +			     SUN4I_TCON_GAMMA_TABLE_R(r) |
> +			     SUN4I_TCON_GAMMA_TABLE_G(g) |
> +			     SUN4I_TCON_GAMMA_TABLE_B(b));
> +	}
> +}
> +EXPORT_SYMBOL(sun4i_tcon_load_gamma_lut);
> +
> +void sun4i_tcon_enable_gamma(struct sun4i_tcon *tcon, bool enable)
> +{
> +	regmap_update_bits(tcon->regs, SUN4I_TCON_GCTL_REG,
> +			   SUN4I_TCON_GCTL_GAMMA_ENABLE,
> +			   enable ? SUN4I_TCON_GCTL_GAMMA_ENABLE : 0);
> +}
> +EXPORT_SYMBOL(sun4i_tcon_enable_gamma);
> +
>  /*
>   * This function is a helper for TCON output muxing. The TCON output
>   * muxing control register in earlier SoCs (without the TCON TOP block)
> @@ -1261,6 +1289,11 @@ static int sun4i_tcon_bind(struct device *dev, struct device *master,
>  
>  	list_add_tail(&tcon->list, &drv->tcon_list);
>  
> +	drm_mode_crtc_set_gamma_size(&tcon->crtc->crtc,
> +				     SUN4I_TCON_GAMMA_LUT_SIZE);
> +	drm_crtc_enable_color_mgmt(&tcon->crtc->crtc, 0, false,
> +				   tcon->crtc->crtc.gamma_size);
> +
>  	return 0;
>  
>  err_free_dotclock:
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.h b/drivers/gpu/drm/sun4i/sun4i_tcon.h
> index 84cfb1952ff7..68a29e49e426 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.h
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.h
> @@ -22,6 +22,7 @@
>  
>  #define SUN4I_TCON_GCTL_REG			0x0
>  #define SUN4I_TCON_GCTL_TCON_ENABLE			BIT(31)
> +#define SUN4I_TCON_GCTL_GAMMA_ENABLE			BIT(30)
>  #define SUN4I_TCON_GCTL_IOMAP_MASK			BIT(0)
>  #define SUN4I_TCON_GCTL_IOMAP_TCON1			(1 << 0)
>  #define SUN4I_TCON_GCTL_IOMAP_TCON0			(0 << 0)
> @@ -215,7 +216,13 @@
>  #define SUN4I_TCON1_FILL_BEG2_REG		0x31c
>  #define SUN4I_TCON1_FILL_END2_REG		0x320
>  #define SUN4I_TCON1_FILL_DATA2_REG		0x324
> -#define SUN4I_TCON1_GAMMA_TABLE_REG		0x400
> +
> +#define SUN4I_TCON_GAMMA_TABLE_REG		0x400
> +#define SUN4I_TCON_GAMMA_TABLE_B(x)		((x) & 0xff)
> +#define SUN4I_TCON_GAMMA_TABLE_G(x)		(((x) & 0xff) << 8)
> +#define SUN4I_TCON_GAMMA_TABLE_R(x)		(((x) & 0xff) << 16)
> +
> +#define SUN4I_TCON_GAMMA_LUT_SIZE		256
>  
>  #define SUN4I_TCON_MAX_CHANNELS		2
>  
> @@ -278,6 +285,9 @@ void sun4i_tcon_mode_set(struct sun4i_tcon *tcon,
>  			 const struct drm_display_mode *mode);
>  void sun4i_tcon_set_status(struct sun4i_tcon *crtc,
>  			   const struct drm_encoder *encoder, bool enable);
> +void sun4i_tcon_load_gamma_lut(struct sun4i_tcon *tcon,
> +			       struct drm_color_lut *lut);
> +void sun4i_tcon_enable_gamma(struct sun4i_tcon *tcon, bool enable);
>  
>  extern const struct of_device_id sun4i_tcon_of_table[];
>  
> -- 
> 2.21.0
> 

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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