Re: [PATCH 1/2] drm/mediatek: Add gamma correction

From: Daniel Vetter
Date: Tue Jun 14 2016 - 01:43:42 EST

On Tue, Jun 14, 2016 at 10:55:52AM +0800, Bibby Hsieh wrote:
> Apply gamma function to correct brightness values.
> It applies arbitrary mapping curve to compensate the
> incorrect transfer function of the panel.
>
> Signed-off-by: Bibby Hsieh <bibby.hsieh@xxxxxxxxxxxx>

I think it would be much better to use the new atomic color management
support, which includes gamma. See drm_crtc_enable_color_mgmt.
-Daniel

> ---
> drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 12 ++++++
> drivers/gpu/drm/mediatek/mtk_drm_crtc.h | 1 +
> drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c | 56 ++++++++++++++++++++++++++-
> drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h | 9 +++++
> 4 files changed, 77 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> index 24aa3ba..1b38406 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> @@ -127,6 +127,16 @@ static void mtk_drm_crtc_reset(struct drm_crtc *crtc)
> state->base.crtc = crtc;
> }
>
> +static void mtk_crtc_gamma_set(struct drm_crtc *crtc, u16 *r,
> + u16 *g, u16 *b, uint32_t start, uint32_t size)
> +{
> + struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
> + unsigned int i;
> +
> + for (i = 0; i < mtk_crtc->ddp_comp_nr; i++)
> + mtk_ddp_gamma_set(mtk_crtc->ddp_comp[i], r, g, b, start, size);
> +}
> +
> static struct drm_crtc_state *mtk_drm_crtc_duplicate_state(struct drm_crtc *crtc)
> {
> struct mtk_crtc_state *state;
> @@ -418,6 +428,7 @@ static const struct drm_crtc_funcs mtk_crtc_funcs = {
> .reset = mtk_drm_crtc_reset,
> .atomic_duplicate_state = mtk_drm_crtc_duplicate_state,
> .atomic_destroy_state = mtk_drm_crtc_destroy_state,
> + .gamma_set = mtk_crtc_gamma_set,
> };
>
> static const struct drm_crtc_helper_funcs mtk_crtc_helper_funcs = {
> @@ -569,6 +580,7 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
> if (ret < 0)
> goto unprepare;
>
> + drm_mode_crtc_set_gamma_size(&mtk_crtc->base, MTK_LUT_SIZE);
> priv->crtc[pipe] = &mtk_crtc->base;
> priv->num_pipes++;
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.h b/drivers/gpu/drm/mediatek/mtk_drm_crtc.h
> index 81e5566..d332564 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.h
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.h
> @@ -19,6 +19,7 @@
> #include "mtk_drm_plane.h"
>
> #define OVL_LAYER_NR 4
> +#define MTK_LUT_SIZE 512
>
> int mtk_drm_crtc_enable_vblank(struct drm_device *drm, unsigned int pipe);
> void mtk_drm_crtc_disable_vblank(struct drm_device *drm, unsigned int pipe);
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
> index 3970fcf..3fd5141 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
> @@ -24,6 +24,7 @@
> #include "mtk_drm_drv.h"
> #include "mtk_drm_plane.h"
> #include "mtk_drm_ddp_comp.h"
> +#include "mtk_drm_crtc.h"
>
> #define DISP_OD_EN 0x0000
> #define DISP_OD_INTEN 0x0008
> @@ -38,6 +39,18 @@
> #define DISP_COLOR_WIDTH 0x0c50
> #define DISP_COLOR_HEIGHT 0x0c54
>
> +#define DISP_AAL_EN 0x000
> +#define DISP_AAL_SIZE 0x030
> +
> +#define DISP_GAMMA_CFG 0x020
> +#define DISP_GAMMA_LUT 0x700
> +
> +#define LUT_10BIT_MASK 0x3ff
> +
> +#define AAL_EN BIT(0)
> +
> +#define GAMMA_LUT_EN BIT(1)
> +
> #define OD_RELAY_MODE BIT(0)
>
> #define UFO_BYPASS BIT(2)
> @@ -76,6 +89,40 @@ static void mtk_ufoe_start(struct mtk_ddp_comp *comp)
> writel(UFO_BYPASS, comp->regs + DISP_REG_UFO_START);
> }
>
> +static void mtk_aal_config(struct mtk_ddp_comp *comp, unsigned int w,
> + unsigned int h, unsigned int vrefresh)
> +{
> + writel(h << 16 | w, comp->regs + DISP_AAL_SIZE);
> +}
> +
> +static void mtk_aal_start(struct mtk_ddp_comp *comp)
> +{
> + writel(AAL_EN, comp->regs + DISP_AAL_EN);
> +}
> +
> +static void mtk_aal_stop(struct mtk_ddp_comp *comp)
> +{
> + writel_relaxed(0x0, comp->regs + DISP_AAL_EN);
> +}
> +
> +static void mtk_gamma_set(struct mtk_ddp_comp *comp, u16 *r, u16 *g,
> + u16 *b, uint32_t start, uint32_t size)
> +{
> + int i;
> + unsigned int lut;
> + int end = (start + size > MTK_LUT_SIZE) ? MTK_LUT_SIZE : start + size;
> + void __iomem *lut_base;
> +
> + writel(GAMMA_LUT_EN, comp->regs + DISP_GAMMA_CFG);
> + lut_base = comp->regs + DISP_GAMMA_LUT;
> + for (i = start; i < end; i++) {
> + lut = (((r[i] >> 6) & LUT_10BIT_MASK) << 20) +
> + (((g[i] >> 6) & LUT_10BIT_MASK) << 10) +
> + ((b[i] >> 6) & LUT_10BIT_MASK);
> + writel(lut, (lut_base + i * 4));
> + }
> +}
> +
> static const struct mtk_ddp_comp_funcs ddp_color = {
> .config = mtk_color_config,
> .start = mtk_color_start,
> @@ -90,6 +137,13 @@ static const struct mtk_ddp_comp_funcs ddp_ufoe = {
> .start = mtk_ufoe_start,
> };
>
> +static const struct mtk_ddp_comp_funcs ddp_aal = {
> + .gamma_set = mtk_gamma_set,
> + .config = mtk_aal_config,
> + .start = mtk_aal_start,
> + .stop = mtk_aal_stop,
> +};
> +
> static const char * const mtk_ddp_comp_stem[MTK_DDP_COMP_TYPE_MAX] = {
> [MTK_DISP_OVL] = "ovl",
> [MTK_DISP_RDMA] = "rdma",
> @@ -112,7 +166,7 @@ struct mtk_ddp_comp_match {
> };
>
> static const struct mtk_ddp_comp_match mtk_ddp_matches[DDP_COMPONENT_ID_MAX] = {
> - [DDP_COMPONENT_AAL] = { MTK_DISP_AAL, 0, NULL },
> + [DDP_COMPONENT_AAL] = { MTK_DISP_AAL, 0, &ddp_aal },
> [DDP_COMPONENT_COLOR0] = { MTK_DISP_COLOR, 0, &ddp_color },
> [DDP_COMPONENT_COLOR1] = { MTK_DISP_COLOR, 1, &ddp_color },
> [DDP_COMPONENT_DPI0] = { MTK_DPI, 0, NULL },
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h
> index 6b13ba9..0832179 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h
> @@ -73,6 +73,8 @@ struct mtk_ddp_comp_funcs {
> void (*layer_off)(struct mtk_ddp_comp *comp, unsigned int idx);
> void (*layer_config)(struct mtk_ddp_comp *comp, unsigned int idx,
> struct mtk_plane_state *state);
> + void (*gamma_set)(struct mtk_ddp_comp *comp, u16 *r, u16 *g, u16 *b,
> + u32 start, u32 size);
> };
>
> struct mtk_ddp_comp {
> @@ -139,6 +141,13 @@ static inline void mtk_ddp_comp_layer_config(struct mtk_ddp_comp *comp,
> comp->funcs->layer_config(comp, idx, state);
> }
>
> +static inline void mtk_ddp_gamma_set(struct mtk_ddp_comp *comp, u16 *r, u16 *g,
> + u16 *b, uint32_t start, uint32_t size)
> +{
> + if (comp->funcs && comp->funcs->gamma_set)
> + comp->funcs->gamma_set(comp, r, g, b, start, size);
> +}
> +
> int mtk_ddp_comp_get_id(struct device_node *node,
> enum mtk_ddp_comp_type comp_type);
> int mtk_ddp_comp_init(struct device *dev, struct device_node *comp_node,
> --
> 1.7.9.5
>

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch