drm/ingenic: Use the highest possible DMA burst size

Until now, when running at the maximum resolution of 1280x720 at 32bpp
on the JZ4770 SoC the output was garbled, the X/Y position of the
top-left corner of the framebuffer warping to a random position with
the whole image being offset accordingly, every time a new frame was
being submitted.

This problem can be eliminated by using a bigger burst size for the DMA.

Set in each soc_info structure the maximum burst size supported by the
corresponding SoC, and use it in the driver.

Set the new value using regmap_update_bits() instead of
regmap_set_bits(), since we do want to override the old value of the
burst size. (Note that regmap_set_bits() wasn't really valid before for
the same reason, but it never seemed to be a problem).

Cc: <[e-mail]>
Fixes: 90b86fcc47b4 ("DRM: Add KMS driver for the Ingenic JZ47xx SoCs")
Signed-off-by: Paul Cercueil <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Acked-by: Sam Ravnborg <[e-mail]>
Tested-by: Christophe Branchereau <[e-mail]>

drivers/gpu/drm/ingenic/ingenic-drm-drv.c

···
 	bool map_noncoherent;
 	bool use_extended_hwdesc;
 	bool plane_f0_not_working;
+	u32 max_burst;
 	unsigned int max_width, max_height;
 	const u32 *formats_f0, *formats_f1;
 	unsigned int num_formats_f0, num_formats_f1;
···
 		regmap_write(priv->map, JZ_REG_LCD_REV, mode->htotal << 16);
 	}
 
-	regmap_set_bits(priv->map, JZ_REG_LCD_CTRL,
-			JZ_LCD_CTRL_OFUP | JZ_LCD_CTRL_BURST_16);
+	regmap_update_bits(priv->map, JZ_REG_LCD_CTRL,
+			   JZ_LCD_CTRL_OFUP | JZ_LCD_CTRL_BURST_MASK,
+			   JZ_LCD_CTRL_OFUP | priv->soc_info->max_burst);
 
 	/*
 	 * IPU restart - specify how much time the LCDC will wait before
···
 	.map_noncoherent = false,
 	.max_width = 800,
 	.max_height = 600,
+	.max_burst = JZ_LCD_CTRL_BURST_16,
 	.formats_f1 = jz4740_formats,
 	.num_formats_f1 = ARRAY_SIZE(jz4740_formats),
 	/* JZ4740 has only one plane */
···
 	.map_noncoherent = false,
 	.max_width = 800,
 	.max_height = 600,
+	.max_burst = JZ_LCD_CTRL_BURST_16,
 	.formats_f1 = jz4725b_formats_f1,
 	.num_formats_f1 = ARRAY_SIZE(jz4725b_formats_f1),
 	.formats_f0 = jz4725b_formats_f0,
···
 	.map_noncoherent = true,
 	.max_width = 1280,
 	.max_height = 720,
+	.max_burst = JZ_LCD_CTRL_BURST_64,
 	.formats_f1 = jz4770_formats_f1,
 	.num_formats_f1 = ARRAY_SIZE(jz4770_formats_f1),
 	.formats_f0 = jz4770_formats_f0,
···
 	.plane_f0_not_working = true,	/* REVISIT */
 	.max_width = 4096,
 	.max_height = 2048,
+	.max_burst = JZ_LCD_CTRL_BURST_64,
 	.formats_f1 = jz4770_formats_f1,
 	.num_formats_f1 = ARRAY_SIZE(jz4770_formats_f1),
 	.formats_f0 = jz4770_formats_f0,

drivers/gpu/drm/ingenic/ingenic-drm.h

···
 #define JZ_LCD_CTRL_BURST_4			(0x0 << 28)
 #define JZ_LCD_CTRL_BURST_8			(0x1 << 28)
 #define JZ_LCD_CTRL_BURST_16			(0x2 << 28)
+#define JZ_LCD_CTRL_BURST_32			(0x3 << 28)
+#define JZ_LCD_CTRL_BURST_64			(0x4 << 28)
+#define JZ_LCD_CTRL_BURST_MASK			(0x7 << 28)
 #define JZ_LCD_CTRL_RGB555			BIT(27)
 #define JZ_LCD_CTRL_OFUP			BIT(26)
 #define JZ_LCD_CTRL_FRC_GRAYSCALE_16		(0x0 << 24)