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Commit b706a25e authored by Philippe CORNU's avatar Philippe CORNU Committed by Benjamin Gaignard
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drm/stm: ltdc: add clut mode support 



Add the 8-bit clut mode support at crtc level.
Useful for low memory footprint user interfaces but also for
8-bit old games (including color shifting visual effects).
Tested with fbdev FBIOPUTCMAP & drm DRM_IOCTL_MODE_SETGAMMA
ioctls.

Signed-off-by: default avatarPhilippe Cornu <philippe.cornu@st.com>
Signed-off-by: default avatarBenjamin Gaignard <benjamin.gaignard@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1509016666-18927-1-git-send-email-philippe.cornu@st.com
parent c4712f27

drivers/gpu/drm/stm/ltdc.c

+30 −0
Original line number Diff line number Diff line
@@ -175,6 +175,8 @@ 


#define LXCFBLNR_CFBLN	GENMASK(10, 0)	/* Color Frame Buffer Line Number */



#define CLUT_SIZE	256



#define CONSTA_MAX	0xFF		/* CONSTant Alpha MAX= 1.0 */

#define BF1_PAXCA	0x600		/* Pixel Alpha x Constant Alpha */

#define BF1_CA		0x400		/* Constant Alpha */
@@ -363,6 +365,28 @@ static irqreturn_t ltdc_irq(int irq, void *arg) 
 * DRM_CRTC

 */



static void ltdc_crtc_update_clut(struct drm_crtc *crtc)

{

	struct ltdc_device *ldev = crtc_to_ltdc(crtc);

	struct drm_color_lut *lut;

	u32 val;

	int i;



	if (!crtc || !crtc->state)

		return;



	if (!crtc->state->color_mgmt_changed || !crtc->state->gamma_lut)

		return;



	lut = (struct drm_color_lut *)crtc->state->gamma_lut->data;



	for (i = 0; i < CLUT_SIZE; i++, lut++) {

		val = ((lut->red << 8) & 0xff0000) | (lut->green & 0xff00) |

			(lut->blue >> 8) | (i << 24);

		reg_write(ldev->regs, LTDC_L1CLUTWR, val);

	}

}



static void ltdc_crtc_atomic_enable(struct drm_crtc *crtc,

				    struct drm_crtc_state *old_state)

{
@@ -486,6 +510,8 @@ static void ltdc_crtc_atomic_flush(struct drm_crtc *crtc, 


	DRM_DEBUG_ATOMIC("\n");



	ltdc_crtc_update_clut(crtc);



	/* Commit shadow registers = update planes at next vblank */

	reg_set(ldev->regs, LTDC_SRCR, SRCR_VBR);
@@ -533,6 +559,7 @@ static const struct drm_crtc_funcs ltdc_crtc_funcs = { 
	.reset = drm_atomic_helper_crtc_reset,

	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,

	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,

	.gamma_set = drm_atomic_helper_legacy_gamma_set,

};



/*
@@ -765,6 +792,9 @@ static int ltdc_crtc_init(struct drm_device *ddev, struct drm_crtc *crtc) 


	drm_crtc_helper_add(crtc, &ltdc_crtc_helper_funcs);



	drm_mode_crtc_set_gamma_size(crtc, CLUT_SIZE);

	drm_crtc_enable_color_mgmt(crtc, 0, false, CLUT_SIZE);



	DRM_DEBUG_DRIVER("CRTC:%d created\n", crtc->base.id);



	/* Add planes. Note : the first layer is used by primary plane */