Merge branch 'next' of git://git.denx.de/u-boot-video

drivers/video/Kconfig

@@ -14,6 +14,27 @@ config DM_VIDEO
 	  option compiles in the video uclass and routes all LCD/video access
 	  through this.
 
+config BACKLIGHT_PWM
+	bool "Generic PWM based Backlight Driver"
+	depends on DM_VIDEO && DM_PWM
+	default y
+	help
+	  If you have a LCD backlight adjustable by PWM, say Y to enable
+	  this driver.
+	  This driver can be use with "simple-panel" and
+	  it understands the standard device tree
+	  (leds/backlight/pwm-backlight.txt)
+
+config BACKLIGHT_GPIO
+	bool "Generic GPIO based Backlight Driver"
+	depends on DM_VIDEO
+	help
+	  If you have a LCD backlight adjustable by GPIO, say Y to enable
+	  this driver.
+	  This driver can be used with "simple-panel" and
+	  it understands the standard device tree
+	  (leds/backlight/gpio-backlight.txt)
+
 config VIDEO_BPP8
 	bool "Support 8-bit-per-pixel displays"
 	depends on DM_VIDEO
@@ -98,6 +119,14 @@ config SYS_WHITE_ON_BLACK
 	 better in low-light situations or to reduce eye strain in some
 	 cases.
 
+config NO_FB_CLEAR
+	bool "Skip framebuffer clear"
+	help
+	  If firmware (whatever loads u-boot) has already put a splash image
+	  on screen, you might want to preserve it until whatever u-boot
+	  loads takes over the screen.  This, for example, can be used to
+	  keep splash image on screen until grub graphical boot menu starts.
+
 source "drivers/video/fonts/Kconfig"
 
 config VIDCONSOLE_AS_LCD
@@ -436,6 +465,8 @@ config VIDEO_SANDBOX_SDL
 	  console device and can display stdout output. Within U-Boot is is
 	  a normal bitmap display and can display images as well as text.
 
+source "drivers/video/stm32/Kconfig"
+
 config VIDEO_TEGRA20
 	bool "Enable LCD support on Tegra20"
 	depends on OF_CONTROL
@@ -601,4 +632,14 @@ config VIDEO_DW_HDMI
 	  rather requires a SoC-specific glue driver to call it), it
 	  can not be enabled from the configuration menu.
 
+config VIDEO_SIMPLE
+	bool "Simple display driver for preconfigured display"
+	help
+	  Enables a simple generic display driver which utilizes the
+	  simple-framebuffer devicetree bindings.
+
+	  This driver assumes that the display hardware has been initialized
+	  before u-boot starts, and u-boot will simply render to the pre-
+	  allocated frame buffer surface.
+
 endmenu

drivers/video/Makefile

@@ -11,9 +11,8 @@ obj-$(CONFIG_DM_VIDEO) += backlight-uclass.o
 obj-$(CONFIG_DM_VIDEO) += panel-uclass.o simple_panel.o
 obj-$(CONFIG_DM_VIDEO) += video-uclass.o vidconsole-uclass.o
 obj-$(CONFIG_DM_VIDEO) += video_bmp.o
-ifdef CONFIG_DM_VIDEO
-obj-$(CONFIG_DM_PWM) += pwm_backlight.o
-endif
+obj-$(CONFIG_BACKLIGHT_PWM) += pwm_backlight.o
+obj-$(CONFIG_BACKLIGHT_GPIO) += backlight_gpio.o
 obj-$(CONFIG_CONSOLE_NORMAL) += console_normal.o
 obj-$(CONFIG_CONSOLE_ROTATION) += console_rotate.o
 obj-$(CONFIG_CONSOLE_TRUETYPE) += console_truetype.o fonts/
@@ -53,10 +52,11 @@ obj-$(CONFIG_FORMIKE) += formike.o
 obj-$(CONFIG_LG4573) += lg4573.o
 obj-$(CONFIG_AM335X_LCD) += am335x-fb.o
 obj-$(CONFIG_VIDEO_DW_HDMI) += dw_hdmi.o
-
+obj-$(CONFIG_VIDEO_SIMPLE) += simplefb.o
 obj-${CONFIG_VIDEO_TEGRA124} += tegra124/
 obj-${CONFIG_EXYNOS_FB} += exynos/
 obj-${CONFIG_VIDEO_ROCKCHIP} += rockchip/
+obj-${CONFIG_VIDEO_STM32} += stm32/
 
 obj-y += bridge/
 obj-y += sunxi/

drivers/video/backlight_gpio.c

+/*
+ * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
+ * Author: Patrick Delaunay <patrick.delaunay@st.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <backlight.h>
+#include <asm/gpio.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct gpio_backlight_priv {
+	struct gpio_desc gpio;
+	bool def_value;
+};
+
+static int gpio_backlight_enable(struct udevice *dev)
+{
+	struct gpio_backlight_priv *priv = dev_get_priv(dev);
+
+	dm_gpio_set_value(&priv->gpio, 1);
+
+	return 0;
+}
+
+static int gpio_backlight_ofdata_to_platdata(struct udevice *dev)
+{
+	struct gpio_backlight_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	ret = gpio_request_by_name(dev, "gpios", 0, &priv->gpio,
+				   GPIOD_IS_OUT);
+	if (ret) {
+		debug("%s: Warning: cannot get GPIO: ret=%d\n",
+		      __func__, ret);
+		return ret;
+	}
+
+	priv->def_value = dev_read_bool(dev, "default-on");
+
+	return 0;
+}
+
+static int gpio_backlight_probe(struct udevice *dev)
+{
+	struct gpio_backlight_priv *priv = dev_get_priv(dev);
+
+	if (priv->def_value)
+		gpio_backlight_enable(dev);
+
+	return 0;
+}
+
+static const struct backlight_ops gpio_backlight_ops = {
+	.enable	= gpio_backlight_enable,
+};
+
+static const struct udevice_id gpio_backlight_ids[] = {
+	{ .compatible = "gpio-backlight" },
+	{ }
+};
+
+U_BOOT_DRIVER(gpio_backlight) = {
+	.name	= "gpio_backlight",
+	.id	= UCLASS_PANEL_BACKLIGHT,
+	.of_match = gpio_backlight_ids,
+	.ops	= &gpio_backlight_ops,
+	.ofdata_to_platdata	= gpio_backlight_ofdata_to_platdata,
+	.probe		= gpio_backlight_probe,
+	.priv_auto_alloc_size	= sizeof(struct gpio_backlight_priv),
+};

drivers/video/cfb_console.c

@@ -2081,7 +2081,8 @@ static int cfg_video_init(void)
 	}
 	eorx = fgx ^ bgx;
 
-	video_clear();
+	if (!CONFIG_IS_ENABLED(NO_FB_CLEAR))
+		video_clear();
 
 #ifdef CONFIG_VIDEO_LOGO
 	/* Plot the logo and get start point of console */

drivers/video/simplefb.c

+/*
+ * (C) Copyright 2017 Rob Clark
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <fdtdec.h>
+#include <fdt_support.h>
+#include <video.h>
+
+static int simple_video_probe(struct udevice *dev)
+{
+	struct video_uc_platdata *plat = dev_get_uclass_platdata(dev);
+	struct video_priv *uc_priv = dev_get_uclass_priv(dev);
+	const void *blob = gd->fdt_blob;
+	const int node = dev_of_offset(dev);
+	const char *format;
+	fdt_addr_t base;
+	fdt_size_t size;
+
+	base = fdtdec_get_addr_size_auto_parent(blob, dev_of_offset(dev->parent),
+			node, "reg", 0, &size, false);
+	if (base == FDT_ADDR_T_NONE) {
+		debug("%s: Failed to decode memory region\n", __func__);
+		return -EINVAL;
+	}
+
+	debug("%s: base=%llx, size=%llu\n", __func__, base, size);
+
+	/*
+	 * TODO is there some way to reserve the framebuffer
+	 * region so it isn't clobbered?
+	 */
+	plat->base = base;
+	plat->size = size;
+
+	video_set_flush_dcache(dev, true);
+
+	debug("%s: Query resolution...\n", __func__);
+
+	uc_priv->xsize = fdtdec_get_uint(blob, node, "width", 0);
+	uc_priv->ysize = fdtdec_get_uint(blob, node, "height", 0);
+	uc_priv->rot = 0;
+
+	format = fdt_getprop(blob, node, "format", NULL);
+	debug("%s: %dx%d@%s\n", __func__, uc_priv->xsize, uc_priv->ysize, format);
+
+	if (strcmp(format, "r5g6b5") == 0) {
+		uc_priv->bpix = VIDEO_BPP16;
+	} else if (strcmp(format, "a8b8g8r8") == 0) {
+		uc_priv->bpix = VIDEO_BPP32;
+	} else {
+		printf("%s: invalid format: %s\n", __func__, format);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct udevice_id simple_video_ids[] = {
+	{ .compatible = "simple-framebuffer" },
+	{ }
+};
+
+U_BOOT_DRIVER(simple_video) = {
+	.name	= "simple_video",
+	.id	= UCLASS_VIDEO,
+	.of_match = simple_video_ids,
+	.probe	= simple_video_probe,
+	.flags	= DM_FLAG_PRE_RELOC,
+};

drivers/video/stm32/Kconfig

+#
+# Copyright (C) STMicroelectronics SA 2017
+#
+# Authors: Philippe Cornu <philippe.cornu@st.com>
+#          Yannick Fertre <yannick.fertre@st.com>
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+menuconfig VIDEO_STM32
+	bool "Enable STM32 video support"
+	depends on DM_VIDEO
+	help
+	  STM32 supports many video output options including RGB and
+	  DSI. This option enables these supports which can be used on
+	  devices which have RGB TFT or DSI display connected.
+
+config VIDEO_STM32_MAX_XRES
+	int "Maximum horizontal resolution (for memory allocation purposes)"
+	depends on VIDEO_STM32
+	default 640
+	help
+	  The maximum horizontal resolution to support for the framebuffer.
+	  This configuration is used for reserving/allocating memory for the
+	  framebuffer during device-model binding/probing.
+
+config VIDEO_STM32_MAX_YRES
+	int "Maximum vertical resolution (for memory allocation purposes)"
+	depends on VIDEO_STM32
+	default 480
+	help
+	  The maximum vertical resolution to support for the framebuffer.
+	  This configuration is used for reserving/allocating memory for the
+	  framebuffer during device-model binding/probing.
+
+config VIDEO_STM32_MAX_BPP
+	int "Maximum bits per pixel (for memory allocation purposes)"
+	depends on VIDEO_STM32
+	default 16
+	help
+	  The maximum bits per pixel to support for the framebuffer.
+	  This configuration is used for reserving/allocating memory for the
+	  framebuffer during device-model binding/probing.
+

drivers/video/stm32/Makefile

+#
+# Copyright (C) STMicroelectronics SA 2017
+#
+# Authors: Philippe Cornu <philippe.cornu@st.com>
+#          Yannick Fertre <yannick.fertre@st.com>
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+obj-${CONFIG_VIDEO_STM32} = stm32_ltdc.o

drivers/video/stm32/stm32_ltdc.c

+/*
+ * Copyright (C) STMicroelectronics SA 2017
+ *
+ * Authors: Philippe Cornu <philippe.cornu@st.com>
+ *          Yannick Fertre <yannick.fertre@st.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <panel.h>
+#include <video.h>
+#include <asm/io.h>
+#include <asm/arch/gpio.h>
+#include <dm/device-internal.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct stm32_ltdc_priv {
+	void __iomem *regs;
+	struct display_timing timing;
+	enum video_log2_bpp l2bpp;
+	u32 bg_col_argb;
+	u32 crop_x, crop_y, crop_w, crop_h;
+	u32 alpha;
+};
+
+/* LTDC main registers */
+#define LTDC_IDR	0x00	/* IDentification */
+#define LTDC_LCR	0x04	/* Layer Count */
+#define LTDC_SSCR	0x08	/* Synchronization Size Configuration */
+#define LTDC_BPCR	0x0C	/* Back Porch Configuration */
+#define LTDC_AWCR	0x10	/* Active Width Configuration */
+#define LTDC_TWCR	0x14	/* Total Width Configuration */
+#define LTDC_GCR	0x18	/* Global Control */
+#define LTDC_GC1R	0x1C	/* Global Configuration 1 */
+#define LTDC_GC2R	0x20	/* Global Configuration 2 */
+#define LTDC_SRCR	0x24	/* Shadow Reload Configuration */
+#define LTDC_GACR	0x28	/* GAmma Correction */
+#define LTDC_BCCR	0x2C	/* Background Color Configuration */
+#define LTDC_IER	0x34	/* Interrupt Enable */
+#define LTDC_ISR	0x38	/* Interrupt Status */
+#define LTDC_ICR	0x3C	/* Interrupt Clear */
+#define LTDC_LIPCR	0x40	/* Line Interrupt Position Conf. */
+#define LTDC_CPSR	0x44	/* Current Position Status */
+#define LTDC_CDSR	0x48	/* Current Display Status */
+
+/* LTDC layer 1 registers */
+#define LTDC_L1LC1R	0x80	/* L1 Layer Configuration 1 */
+#define LTDC_L1LC2R	0x84	/* L1 Layer Configuration 2 */
+#define LTDC_L1CR	0x84	/* L1 Control */
+#define LTDC_L1WHPCR	0x88	/* L1 Window Hor Position Config */
+#define LTDC_L1WVPCR	0x8C	/* L1 Window Vert Position Config */
+#define LTDC_L1CKCR	0x90	/* L1 Color Keying Configuration */
+#define LTDC_L1PFCR	0x94	/* L1 Pixel Format Configuration */
+#define LTDC_L1CACR	0x98	/* L1 Constant Alpha Config */
+#define LTDC_L1DCCR	0x9C	/* L1 Default Color Configuration */
+#define LTDC_L1BFCR	0xA0	/* L1 Blend Factors Configuration */
+#define LTDC_L1FBBCR	0xA4	/* L1 FrameBuffer Bus Control */
+#define LTDC_L1AFBCR	0xA8	/* L1 AuxFB Control */
+#define LTDC_L1CFBAR	0xAC	/* L1 Color FrameBuffer Address */
+#define LTDC_L1CFBLR	0xB0	/* L1 Color FrameBuffer Length */
+#define LTDC_L1CFBLNR	0xB4	/* L1 Color FrameBuffer Line Nb */
+#define LTDC_L1AFBAR	0xB8	/* L1 AuxFB Address */
+#define LTDC_L1AFBLR	0xBC	/* L1 AuxFB Length */
+#define LTDC_L1AFBLNR	0xC0	/* L1 AuxFB Line Number */
+#define LTDC_L1CLUTWR	0xC4	/* L1 CLUT Write */
+
+/* Bit definitions */
+#define SSCR_VSH	GENMASK(10, 0)	/* Vertical Synchronization Height */
+#define SSCR_HSW	GENMASK(27, 16)	/* Horizontal Synchronization Width */
+
+#define BPCR_AVBP	GENMASK(10, 0)	/* Accumulated Vertical Back Porch */
+#define BPCR_AHBP	GENMASK(27, 16)	/* Accumulated Horizontal Back Porch */
+
+#define AWCR_AAH	GENMASK(10, 0)	/* Accumulated Active Height */
+#define AWCR_AAW	GENMASK(27, 16)	/* Accumulated Active Width */
+
+#define TWCR_TOTALH	GENMASK(10, 0)	/* TOTAL Height */
+#define TWCR_TOTALW	GENMASK(27, 16)	/* TOTAL Width */
+
+#define GCR_LTDCEN	BIT(0)		/* LTDC ENable */
+#define GCR_DEN		BIT(16)		/* Dither ENable */
+#define GCR_PCPOL	BIT(28)		/* Pixel Clock POLarity-Inverted */
+#define GCR_DEPOL	BIT(29)		/* Data Enable POLarity-High */
+#define GCR_VSPOL	BIT(30)		/* Vertical Synchro POLarity-High */
+#define GCR_HSPOL	BIT(31)		/* Horizontal Synchro POLarity-High */
+
+#define GC1R_WBCH	GENMASK(3, 0)	/* Width of Blue CHannel output */
+#define GC1R_WGCH	GENMASK(7, 4)	/* Width of Green Channel output */
+#define GC1R_WRCH	GENMASK(11, 8)	/* Width of Red Channel output */
+#define GC1R_PBEN	BIT(12)		/* Precise Blending ENable */
+#define GC1R_DT		GENMASK(15, 14)	/* Dithering Technique */
+#define GC1R_GCT	GENMASK(19, 17)	/* Gamma Correction Technique */
+#define GC1R_SHREN	BIT(21)		/* SHadow Registers ENabled */
+#define GC1R_BCP	BIT(22)		/* Background Colour Programmable */
+#define GC1R_BBEN	BIT(23)		/* Background Blending ENabled */
+#define GC1R_LNIP	BIT(24)		/* Line Number IRQ Position */
+#define GC1R_TP		BIT(25)		/* Timing Programmable */
+#define GC1R_IPP	BIT(26)		/* IRQ Polarity Programmable */
+#define GC1R_SPP	BIT(27)		/* Sync Polarity Programmable */
+#define GC1R_DWP	BIT(28)		/* Dither Width Programmable */
+#define GC1R_STREN	BIT(29)		/* STatus Registers ENabled */
+#define GC1R_BMEN	BIT(31)		/* Blind Mode ENabled */
+
+#define GC2R_EDCA	BIT(0)		/* External Display Control Ability  */
+#define GC2R_STSAEN	BIT(1)		/* Slave Timing Sync Ability ENabled */
+#define GC2R_DVAEN	BIT(2)		/* Dual-View Ability ENabled */
+#define GC2R_DPAEN	BIT(3)		/* Dual-Port Ability ENabled */
+#define GC2R_BW		GENMASK(6, 4)	/* Bus Width (log2 of nb of bytes) */
+#define GC2R_EDCEN	BIT(7)		/* External Display Control ENabled */
+
+#define SRCR_IMR	BIT(0)		/* IMmediate Reload */
+#define SRCR_VBR	BIT(1)		/* Vertical Blanking Reload */
+
+#define LXCR_LEN	BIT(0)		/* Layer ENable */
+#define LXCR_COLKEN	BIT(1)		/* Color Keying Enable */
+#define LXCR_CLUTEN	BIT(4)		/* Color Look-Up Table ENable */
+
+#define LXWHPCR_WHSTPOS	GENMASK(11, 0)	/* Window Horizontal StarT POSition */
+#define LXWHPCR_WHSPPOS	GENMASK(27, 16)	/* Window Horizontal StoP POSition */
+
+#define LXWVPCR_WVSTPOS	GENMASK(10, 0)	/* Window Vertical StarT POSition */
+#define LXWVPCR_WVSPPOS	GENMASK(26, 16)	/* Window Vertical StoP POSition */
+
+#define LXPFCR_PF	GENMASK(2, 0)	/* Pixel Format */
+
+#define LXCACR_CONSTA	GENMASK(7, 0)	/* CONSTant Alpha */
+
+#define LXBFCR_BF2	GENMASK(2, 0)	/* Blending Factor 2 */
+#define LXBFCR_BF1	GENMASK(10, 8)	/* Blending Factor 1 */
+
+#define LXCFBLR_CFBLL	GENMASK(12, 0)	/* Color Frame Buffer Line Length */
+#define LXCFBLR_CFBP	GENMASK(28, 16)	/* Color Frame Buffer Pitch in bytes */
+
+#define LXCFBLNR_CFBLN	GENMASK(10, 0)	/* Color Frame Buffer Line Number */
+
+#define BF1_PAXCA	0x600		/* Pixel Alpha x Constant Alpha */
+#define BF2_1PAXCA	0x007		/* 1 - (Pixel Alpha x Constant Alpha) */
+
+enum stm32_ltdc_pix_fmt {
+	PF_ARGB8888 = 0,
+	PF_RGB888,
+	PF_RGB565,
+	PF_ARGB1555,
+	PF_ARGB4444,
+	PF_L8,
+	PF_AL44,
+	PF_AL88
+};
+
+/* TODO add more color format support */
+static u32 stm32_ltdc_get_pixel_format(enum video_log2_bpp l2bpp)
+{
+	enum stm32_ltdc_pix_fmt pf;
+
+	switch (l2bpp) {
+	case VIDEO_BPP16:
+		pf = PF_RGB565;
+		break;
+
+	case VIDEO_BPP1:
+	case VIDEO_BPP2:
+	case VIDEO_BPP4:
+	case VIDEO_BPP8:
+	case VIDEO_BPP32:
+	default:
+		debug("%s: warning %dbpp not supported yet, %dbpp instead\n",
+		      __func__, VNBITS(l2bpp), VNBITS(VIDEO_BPP16));
+		pf = PF_RGB565;
+		break;
+	}
+
+	debug("%s: %d bpp -> ltdc pf %d\n", __func__, VNBITS(l2bpp), pf);
+
+	return (u32)pf;
+}
+
+static void stm32_ltdc_enable(struct stm32_ltdc_priv *priv)
+{
+	/* Reload configuration immediately & enable LTDC */
+	setbits_le32(priv->regs + LTDC_SRCR, SRCR_IMR);
+	setbits_le32(priv->regs + LTDC_GCR, GCR_LTDCEN);
+}
+
+static void stm32_ltdc_set_mode(struct stm32_ltdc_priv *priv)
+{
+	void __iomem *regs = priv->regs;
+	struct display_timing *timing = &priv->timing;
+	u32 hsync, vsync, acc_hbp, acc_vbp, acc_act_w, acc_act_h;
+	u32 total_w, total_h;
+	u32 val;
+
+	/* Convert video timings to ltdc timings */
+	hsync = timing->hsync_len.typ - 1;
+	vsync = timing->vsync_len.typ - 1;
+	acc_hbp = hsync + timing->hback_porch.typ;
+	acc_vbp = vsync + timing->vback_porch.typ;
+	acc_act_w = acc_hbp + timing->hactive.typ;
+	acc_act_h = acc_vbp + timing->vactive.typ;
+	total_w = acc_act_w + timing->hfront_porch.typ;
+	total_h = acc_act_h + timing->vfront_porch.typ;
+
+	/* Synchronization sizes */
+	val = (hsync << 16) | vsync;
+	clrsetbits_le32(regs + LTDC_SSCR, SSCR_VSH | SSCR_HSW, val);
+
+	/* Accumulated back porch */
+	val = (acc_hbp << 16) | acc_vbp;
+	clrsetbits_le32(regs + LTDC_BPCR, BPCR_AVBP | BPCR_AHBP, val);
+
+	/* Accumulated active width */
+	val = (acc_act_w << 16) | acc_act_h;
+	clrsetbits_le32(regs + LTDC_AWCR, AWCR_AAW | AWCR_AAH, val);
+
+	/* Total width & height */
+	val = (total_w << 16) | total_h;
+	clrsetbits_le32(regs + LTDC_TWCR, TWCR_TOTALH | TWCR_TOTALW, val);
+
+	/* Signal polarities */
+	val = 0;
+	debug("%s: timing->flags 0x%08x\n", __func__, timing->flags);
+	if (timing->flags & DISPLAY_FLAGS_HSYNC_HIGH)
+		val |= GCR_HSPOL;
+	if (timing->flags & DISPLAY_FLAGS_VSYNC_HIGH)
+		val |= GCR_VSPOL;
+	if (timing->flags & DISPLAY_FLAGS_DE_HIGH)
+		val |= GCR_DEPOL;
+	if (timing->flags & DISPLAY_FLAGS_PIXDATA_NEGEDGE)
+		val |= GCR_PCPOL;
+	clrsetbits_le32(regs + LTDC_GCR,
+			GCR_HSPOL | GCR_VSPOL | GCR_DEPOL | GCR_PCPOL, val);
+
+	/* Overall background color */
+	writel(priv->bg_col_argb, priv->regs + LTDC_BCCR);
+}
+
+static void stm32_ltdc_set_layer1(struct stm32_ltdc_priv *priv, ulong fb_addr)
+{
+	void __iomem *regs = priv->regs;
+	u32 x0, x1, y0, y1;
+	u32 pitch_in_bytes;
+	u32 line_length;
+	u32 bus_width;
+	u32 val, tmp, bpp;
+
+	x0 = priv->crop_x;
+	x1 = priv->crop_x + priv->crop_w - 1;
+	y0 = priv->crop_y;
+	y1 = priv->crop_y + priv->crop_h - 1;
+
+	/* Horizontal start and stop position */
+	tmp = (readl(regs + LTDC_BPCR) & BPCR_AHBP) >> 16;
+	val = ((x1 + 1 + tmp) << 16) + (x0 + 1 + tmp);
+	clrsetbits_le32(regs + LTDC_L1WHPCR, LXWHPCR_WHSTPOS | LXWHPCR_WHSPPOS,
+			val);
+
+	/* Vertical start & stop position */
+	tmp = readl(regs + LTDC_BPCR) & BPCR_AVBP;
+	val = ((y1 + 1 + tmp) << 16) + (y0 + 1 + tmp);
+	clrsetbits_le32(regs + LTDC_L1WVPCR, LXWVPCR_WVSTPOS | LXWVPCR_WVSPPOS,
+			val);
+
+	/* Layer background color */
+	writel(priv->bg_col_argb, regs + LTDC_L1DCCR);
+
+	/* Color frame buffer pitch in bytes & line length */
+	bpp = VNBITS(priv->l2bpp);
+	pitch_in_bytes = priv->crop_w * (bpp >> 3);
+	bus_width = 8 << ((readl(regs + LTDC_GC2R) & GC2R_BW) >> 4);
+	line_length = ((bpp >> 3) * priv->crop_w) + (bus_width >> 3) - 1;
+	val = (pitch_in_bytes << 16) | line_length;
+	clrsetbits_le32(regs + LTDC_L1CFBLR, LXCFBLR_CFBLL | LXCFBLR_CFBP, val);
+
+	/* Pixel format */
+	val = stm32_ltdc_get_pixel_format(priv->l2bpp);
+	clrsetbits_le32(regs + LTDC_L1PFCR, LXPFCR_PF, val);
+
+	/* Constant alpha value */
+	clrsetbits_le32(regs + LTDC_L1CACR, LXCACR_CONSTA, priv->alpha);
+
+	/* Blending factors */
+	clrsetbits_le32(regs + LTDC_L1BFCR, LXBFCR_BF2 | LXBFCR_BF1,
+			BF1_PAXCA | BF2_1PAXCA);
+
+	/* Frame buffer line number */
+	clrsetbits_le32(regs + LTDC_L1CFBLNR, LXCFBLNR_CFBLN, priv->crop_h);
+
+	/* Frame buffer address */
+	writel(fb_addr, regs + LTDC_L1CFBAR);
+
+	/* Enable layer 1 */
+	setbits_le32(priv->regs + LTDC_L1CR, LXCR_LEN);
+}
+
+static int stm32_ltdc_probe(struct udevice *dev)
+{
+	struct video_uc_platdata *uc_plat = dev_get_uclass_platdata(dev);
+	struct video_priv *uc_priv = dev_get_uclass_priv(dev);
+	struct stm32_ltdc_priv *priv = dev_get_priv(dev);
+	struct udevice *panel;
+	struct clk pclk, pxclk;
+	int ret;
+
+	priv->regs = (void *)dev_read_addr(dev);
+	if ((fdt_addr_t)priv->regs == FDT_ADDR_T_NONE) {
+		debug("%s: ltdc dt register address error\n", __func__);
+		return -EINVAL;
+	}
+
+	ret = uclass_first_device(UCLASS_PANEL, &panel);
+	if (ret) {
+		debug("%s: panel device error %d\n", __func__, ret);
+		return ret;
+	}
+
+	ret = panel_enable_backlight(panel);
+	if (ret) {
+		debug("%s: panel %s enable backlight error %d\n",
+		      __func__, panel->name, ret);
+		return ret;
+	}
+
+	ret = fdtdec_decode_display_timing(gd->fdt_blob, dev_of_offset(dev),
+					   0, &priv->timing);
+	if (ret) {
+		debug("%s: decode display timing error %d\n", __func__, ret);
+		return -EINVAL;
+	}
+
+	ret = clk_get_by_name(dev, "pclk", &pclk);
+	if (ret) {
+		debug("%s: peripheral clock get error %d\n", __func__, ret);
+		return ret;
+	}
+
+	ret = clk_enable(&pclk);
+	if (ret) {
+		debug("%s: peripheral clock enable error %d\n", __func__, ret);
+		return ret;
+	}
+
+	/* Verify pixel clock value if any & inform user accordingly */
+	ret = clk_get_by_name(dev, "pxclk", &pxclk);
+	if (!ret) {
+		if (clk_get_rate(&pxclk) != priv->timing.pixelclock.typ)
+			printf("Warning: please adjust ltdc pixel clock\n");
+	}
+
+	/* TODO Below parameters are hard-coded for the moment... */
+	priv->l2bpp = VIDEO_BPP16;
+	priv->bg_col_argb = 0xFFFFFFFF; /* white no transparency */
+	priv->crop_x = 0;
+	priv->crop_y = 0;
+	priv->crop_w = priv->timing.hactive.typ;
+	priv->crop_h = priv->timing.vactive.typ;
+	priv->alpha = 0xFF;
+
+	debug("%s: %dx%d %dbpp frame buffer at 0x%lx\n", __func__,
+	      priv->timing.hactive.typ, priv->timing.vactive.typ,
+	      VNBITS(priv->l2bpp), uc_plat->base);
+	debug("%s: crop %d,%d %dx%d bg 0x%08x alpha %d\n", __func__,
+	      priv->crop_x, priv->crop_y, priv->crop_w, priv->crop_h,
+	      priv->bg_col_argb, priv->alpha);
+
+	/* Configure & start LTDC */
+	stm32_ltdc_set_mode(priv);
+	stm32_ltdc_set_layer1(priv, uc_plat->base);
+	stm32_ltdc_enable(priv);
+
+	uc_priv->xsize = priv->timing.hactive.typ;
+	uc_priv->ysize = priv->timing.vactive.typ;
+	uc_priv->bpix = priv->l2bpp;
+
+	video_set_flush_dcache(dev, true);
+
+	return 0;
+}
+
+static int stm32_ltdc_bind(struct udevice *dev)
+{
+	struct video_uc_platdata *uc_plat = dev_get_uclass_platdata(dev);
+
+	uc_plat->size = CONFIG_VIDEO_STM32_MAX_XRES *
+			CONFIG_VIDEO_STM32_MAX_YRES *
+			(CONFIG_VIDEO_STM32_MAX_BPP >> 3);
+	debug("%s: frame buffer max size %d bytes\n", __func__, uc_plat->size);
+
+	return 0;
+}
+
+static const struct udevice_id stm32_ltdc_ids[] = {
+	{ .compatible = "st,stm32-ltdc" },
+	{ }
+};
+
+U_BOOT_DRIVER(stm32_ltdc) = {
+	.name	= "stm32_ltdc",
+	.id	= UCLASS_VIDEO,
+	.of_match = stm32_ltdc_ids,
+	.probe	= stm32_ltdc_probe,
+	.bind	= stm32_ltdc_bind,
+	.priv_auto_alloc_size	= sizeof(struct stm32_ltdc_priv),
+};

drivers/video/video-uclass.c

@@ -199,7 +199,9 @@ static int video_post_probe(struct udevice *dev)
 #else
 	priv->colour_bg = 0xffffff;
 #endif
-	video_clear(dev);
+
+	if (!CONFIG_IS_ENABLED(NO_FB_CLEAR))
+		video_clear(dev);
 
 	/*
 	 * Create a text console device. For now we always do this, although