sunxi: video: Use frontend for dma on sun4i to fix memory bandwidth problems

Testing has shown that on sun4i the display backend engine does not have
deep enough fifo-s causing flickering / tearing in full-hd mode due to
fifo underruns. On sun4i use the display frontend engine to do the dma from
memory, as the frontend does have deep enough fifo-s.

As added advantage of this is that it results in much better memory bandwidth
as it reduces the amount of dram bank switches, for more details see:

http://ssvb.github.io/2014/11/11/revisiting-fullhd-x11-desktop-performance-of-the-allwinner-a10.html

Note that this changes the pipeline searched for in the simplefb node, we can
get away with doing this now, since no kernel has yet shipped with simplefb
dtb nodes, and I will make sure to get a simplefb node with the new pipeline
into 3.19 before it ships.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>

1 files changed, 130 insertions, 4 deletions

diff --git a/drivers/video/sunxi_display.c b/drivers/video/sunxi_display.c
index 0505f3c..a6e3778 100644
--- a/drivers/video/sunxi_display.c
+++ b/drivers/video/sunxi_display.c
@@ -271,6 +271,114 @@ static int sunxi_hdmi_edid_get_mode(struct ctfb_res_modes *mode)
 
 #endif /* CONFIG_VIDEO_HDMI */
 
+#ifdef CONFIG_MACH_SUN4I
+/*
+ * Testing has shown that on sun4i the display backend engine does not have
+ * deep enough fifo-s causing flickering / tearing in full-hd mode due to
+ * fifo underruns. So on sun4i we use the display frontend engine to do the
+ * dma from memory, as the frontend does have deep enough fifo-s.
+ */
+
+static const u32 sun4i_vert_coef[32] = {
+	0x00004000, 0x000140ff, 0x00033ffe, 0x00043ffd,
+	0x00063efc, 0xff083dfc, 0x000a3bfb, 0xff0d39fb,
+	0xff0f37fb, 0xff1136fa, 0xfe1433fb, 0xfe1631fb,
+	0xfd192ffb, 0xfd1c2cfb, 0xfd1f29fb, 0xfc2127fc,
+	0xfc2424fc, 0xfc2721fc, 0xfb291ffd, 0xfb2c1cfd,
+	0xfb2f19fd, 0xfb3116fe, 0xfb3314fe, 0xfa3611ff,
+	0xfb370fff, 0xfb390dff, 0xfb3b0a00, 0xfc3d08ff,
+	0xfc3e0600, 0xfd3f0400, 0xfe3f0300, 0xff400100,
+};
+
+static const u32 sun4i_horz_coef[64] = {
+	0x40000000, 0x00000000, 0x40fe0000, 0x0000ff03,
+	0x3ffd0000, 0x0000ff05, 0x3ffc0000, 0x0000ff06,
+	0x3efb0000, 0x0000ff08, 0x3dfb0000, 0x0000ff09,
+	0x3bfa0000, 0x0000fe0d, 0x39fa0000, 0x0000fe0f,
+	0x38fa0000, 0x0000fe10, 0x36fa0000, 0x0000fe12,
+	0x33fa0000, 0x0000fd16, 0x31fa0000, 0x0000fd18,
+	0x2ffa0000, 0x0000fd1a, 0x2cfa0000, 0x0000fc1e,
+	0x29fa0000, 0x0000fc21, 0x27fb0000, 0x0000fb23,
+	0x24fb0000, 0x0000fb26, 0x21fb0000, 0x0000fb29,
+	0x1ffc0000, 0x0000fa2b, 0x1cfc0000, 0x0000fa2e,
+	0x19fd0000, 0x0000fa30, 0x16fd0000, 0x0000fa33,
+	0x14fd0000, 0x0000fa35, 0x11fe0000, 0x0000fa37,
+	0x0ffe0000, 0x0000fa39, 0x0dfe0000, 0x0000fa3b,
+	0x0afe0000, 0x0000fa3e, 0x08ff0000, 0x0000fb3e,
+	0x06ff0000, 0x0000fb40, 0x05ff0000, 0x0000fc40,
+	0x03ff0000, 0x0000fd41, 0x01ff0000, 0x0000fe42,
+};
+
+static void sunxi_frontend_init(void)
+{
+	struct sunxi_ccm_reg * const ccm =
+		(struct sunxi_ccm_reg *)SUNXI_CCM_BASE;
+	struct sunxi_de_fe_reg * const de_fe =
+		(struct sunxi_de_fe_reg *)SUNXI_DE_FE0_BASE;
+	int i;
+
+	/* Clocks on */
+	setbits_le32(&ccm->ahb_gate1, 1 << AHB_GATE_OFFSET_DE_FE0);
+	setbits_le32(&ccm->dram_clk_gate, 1 << CCM_DRAM_GATE_OFFSET_DE_FE0);
+	clock_set_de_mod_clock(&ccm->fe0_clk_cfg, 300000000);
+
+	setbits_le32(&de_fe->enable, SUNXI_DE_FE_ENABLE_EN);
+
+	for (i = 0; i < 32; i++) {
+		writel(sun4i_horz_coef[2 * i], &de_fe->ch0_horzcoef0[i]);
+		writel(sun4i_horz_coef[2 * i + 1], &de_fe->ch0_horzcoef1[i]);
+		writel(sun4i_vert_coef[i], &de_fe->ch0_vertcoef[i]);
+		writel(sun4i_horz_coef[2 * i], &de_fe->ch1_horzcoef0[i]);
+		writel(sun4i_horz_coef[2 * i + 1], &de_fe->ch1_horzcoef1[i]);
+		writel(sun4i_vert_coef[i], &de_fe->ch1_vertcoef[i]);
+	}
+
+	setbits_le32(&de_fe->frame_ctrl, SUNXI_DE_FE_FRAME_CTRL_COEF_RDY);
+}
+
+static void sunxi_frontend_mode_set(const struct ctfb_res_modes *mode,
+				    unsigned int address)
+{
+	struct sunxi_de_fe_reg * const de_fe =
+		(struct sunxi_de_fe_reg *)SUNXI_DE_FE0_BASE;
+
+	setbits_le32(&de_fe->bypass, SUNXI_DE_FE_BYPASS_CSC_BYPASS);
+	writel(CONFIG_SYS_SDRAM_BASE + address, &de_fe->ch0_addr);
+	writel(mode->xres * 4, &de_fe->ch0_stride);
+	writel(SUNXI_DE_FE_INPUT_FMT_ARGB8888, &de_fe->input_fmt);
+	writel(SUNXI_DE_FE_OUTPUT_FMT_ARGB8888, &de_fe->output_fmt);
+
+	writel(SUNXI_DE_FE_HEIGHT(mode->yres) | SUNXI_DE_FE_WIDTH(mode->xres),
+	       &de_fe->ch0_insize);
+	writel(SUNXI_DE_FE_HEIGHT(mode->yres) | SUNXI_DE_FE_WIDTH(mode->xres),
+	       &de_fe->ch0_outsize);
+	writel(SUNXI_DE_FE_FACTOR_INT(1), &de_fe->ch0_horzfact);
+	writel(SUNXI_DE_FE_FACTOR_INT(1), &de_fe->ch0_vertfact);
+
+	writel(SUNXI_DE_FE_HEIGHT(mode->yres) | SUNXI_DE_FE_WIDTH(mode->xres),
+	       &de_fe->ch1_insize);
+	writel(SUNXI_DE_FE_HEIGHT(mode->yres) | SUNXI_DE_FE_WIDTH(mode->xres),
+	       &de_fe->ch1_outsize);
+	writel(SUNXI_DE_FE_FACTOR_INT(1), &de_fe->ch1_horzfact);
+	writel(SUNXI_DE_FE_FACTOR_INT(1), &de_fe->ch1_vertfact);
+
+	setbits_le32(&de_fe->frame_ctrl, SUNXI_DE_FE_FRAME_CTRL_REG_RDY);
+}
+
+static void sunxi_frontend_enable(void)
+{
+	struct sunxi_de_fe_reg * const de_fe =
+		(struct sunxi_de_fe_reg *)SUNXI_DE_FE0_BASE;
+
+	setbits_le32(&de_fe->frame_ctrl, SUNXI_DE_FE_FRAME_CTRL_FRM_START);
+}
+#else
+static void sunxi_frontend_init(void) {}
+static void sunxi_frontend_mode_set(const struct ctfb_res_modes *mode,
+				    unsigned int address) {}
+static void sunxi_frontend_enable(void) {}
+#endif
+
 /*
  * This is the entity that mixes and matches the different layers and inputs.
  * Allwinner calls it the back-end, but i like composer better.
@@ -283,6 +391,8 @@ static void sunxi_composer_init(void)
 		(struct sunxi_de_be_reg *)SUNXI_DE_BE0_BASE;
 	int i;
 
+	sunxi_frontend_init();
+
 #if defined CONFIG_MACH_SUN6I || defined CONFIG_MACH_SUN8I
 	/* Reset off */
 	setbits_le32(&ccm->ahb_reset1_cfg, 1 << AHB_RESET_OFFSET_DE_BE0);
@@ -290,7 +400,9 @@ static void sunxi_composer_init(void)
 
 	/* Clocks on */
 	setbits_le32(&ccm->ahb_gate1, 1 << AHB_GATE_OFFSET_DE_BE0);
+#ifndef CONFIG_MACH_SUN4I /* On sun4i the frontend does the dma */
 	setbits_le32(&ccm->dram_clk_gate, 1 << CCM_DRAM_GATE_OFFSET_DE_BE0);
+#endif
 	clock_set_de_mod_clock(&ccm->be0_clk_cfg, 300000000);
 
 	/* Engine bug, clear registers after reset */
@@ -306,13 +418,19 @@ static void sunxi_composer_mode_set(const struct ctfb_res_modes *mode,
 	struct sunxi_de_be_reg * const de_be =
 		(struct sunxi_de_be_reg *)SUNXI_DE_BE0_BASE;
 
+	sunxi_frontend_mode_set(mode, address);
+
 	writel(SUNXI_DE_BE_HEIGHT(mode->yres) | SUNXI_DE_BE_WIDTH(mode->xres),
 	       &de_be->disp_size);
 	writel(SUNXI_DE_BE_HEIGHT(mode->yres) | SUNXI_DE_BE_WIDTH(mode->xres),
 	       &de_be->layer0_size);
+#ifndef CONFIG_MACH_SUN4I /* On sun4i the frontend does the dma */
 	writel(SUNXI_DE_BE_LAYER_STRIDE(mode->xres), &de_be->layer0_stride);
 	writel(address << 3, &de_be->layer0_addr_low32b);
 	writel(address >> 29, &de_be->layer0_addr_high4b);
+#else
+	writel(SUNXI_DE_BE_LAYER_ATTR0_SRC_FE0, &de_be->layer0_attr0_ctrl);
+#endif
 	writel(SUNXI_DE_BE_LAYER_ATTR1_FMT_XRGB8888, &de_be->layer0_attr1_ctrl);
 
 	setbits_le32(&de_be->mode, SUNXI_DE_BE_MODE_LAYER0_ENABLE);
@@ -323,6 +441,8 @@ static void sunxi_composer_enable(void)
 	struct sunxi_de_be_reg * const de_be =
 		(struct sunxi_de_be_reg *)SUNXI_DE_BE0_BASE;
 
+	sunxi_frontend_enable();
+
 	setbits_le32(&de_be->reg_ctrl, SUNXI_DE_BE_REG_CTRL_LOAD_REGS);
 	setbits_le32(&de_be->mode, SUNXI_DE_BE_MODE_START);
 }
@@ -1060,21 +1180,27 @@ int sunxi_simplefb_setup(void *blob)
 	int offset, ret;
 	const char *pipeline = NULL;
 
+#ifdef CONFIG_MACH_SUN4I
+#define PIPELINE_PREFIX "de_fe0-"
+#else
+#define PIPELINE_PREFIX
+#endif
+
 	switch (sunxi_display.monitor) {
 	case sunxi_monitor_none:
 		return 0;
 	case sunxi_monitor_dvi:
 	case sunxi_monitor_hdmi:
-		pipeline = "de_be0-lcd0-hdmi";
+		pipeline = PIPELINE_PREFIX "de_be0-lcd0-hdmi";
 		break;
 	case sunxi_monitor_lcd:
-		pipeline = "de_be0-lcd0";
+		pipeline = PIPELINE_PREFIX "de_be0-lcd0";
 		break;
 	case sunxi_monitor_vga:
 #ifdef CONFIG_VIDEO_VGA
-		pipeline = "de_be0-lcd0-tve0";
+		pipeline = PIPELINE_PREFIX "de_be0-lcd0-tve0";
 #elif defined CONFIG_VIDEO_VGA_VIA_LCD
-		pipeline = "de_be0-lcd0";
+		pipeline = PIPELINE_PREFIX "de_be0-lcd0";
 #endif
 		break;
 	}