[PATCH v12] staging: fbtft: add tearing signal detect

[Carlis <zhangxuezhi3@gmail.com>]

From: zhangxuezhi <zhangxuezhi1@yulong.com>

For st7789v ic,when we need continuous full screen refresh, it is best to
wait for the TE signal arrive to avoid screen tearing

Signed-off-by: zhangxuezhi <zhangxuezhi1@yulong.com>
---
v12: change dev_err to dev_err_probe and add space in comments start, and
     delete te_mutex, change te wait logic
v11: remove devm_gpio_put and change a dev_err to dev_info
v10: additional notes
v9: change pr_* to dev_*
v8: delete a log line
v7: return error value when request fail
v6: add te gpio request fail deal logic
v5: fix log print
v4: modify some code style and change te irq set function name
v3: modify author and signed-off-by name
v2: add release te gpio after irq request fail
---
 drivers/staging/fbtft/fb_st7789v.c | 116 +++++++++++++++++++++++++++++++++++++
 drivers/staging/fbtft/fbtft.h      |   1 +
 2 files changed, 117 insertions(+)

diff --git a/drivers/staging/fbtft/fb_st7789v.c b/drivers/staging/fbtft/fb_st7789v.c
index 3a280cc..f08e9da 100644
--- a/drivers/staging/fbtft/fb_st7789v.c
+++ b/drivers/staging/fbtft/fb_st7789v.c
@@ -9,7 +9,11 @@
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
 #include <linux/module.h>
+#include <linux/gpio/consumer.h>
+
 #include <video/mipi_display.h>
 
 #include "fbtft.h"
@@ -66,6 +70,15 @@ enum st7789v_command {
 #define MADCTL_MX BIT(6) /* bitmask for column address order */
 #define MADCTL_MY BIT(7) /* bitmask for page address order */
 
+#define SPI_PANEL_TE_TIMEOUT	400 /* msecs */
+static struct completion spi_panel_te;
+
+static irqreturn_t spi_panel_te_handler(int irq, void *data)
+{
+	complete(&spi_panel_te);
+	return IRQ_HANDLED;
+}
+
 /**
  * init_display() - initialize the display controller
  *
@@ -82,6 +95,29 @@ enum st7789v_command {
  */
 static int init_display(struct fbtft_par *par)
 {
+	int rc;
+	struct device *dev = par->info->device;
+
+	par->gpio.te = devm_gpiod_get_index_optional(dev, "te", 0, GPIOD_IN);
+	if (IS_ERR(par->gpio.te))
+		return dev_err_probe(par->info->device, PTR_ERR(par->gpio.te),
+				     "Failed to request te gpio\n");
+
+	if (par->gpio.te) {
+		init_completion(&spi_panel_te);
+		rc = devm_request_irq(dev,
+				      gpiod_to_irq(par->gpio.te),
+				     spi_panel_te_handler, IRQF_TRIGGER_RISING,
+				     "TE_GPIO", par);
+		if (IS_ERR(rc))
+			return dev_err_probe(par->info->device, PTR_ERR(rc),
+					     "TE request_irq failed.\n");
+
+		disable_irq_nosync(gpiod_to_irq(par->gpio.te));
+	} else {
+		dev_info(par->info->device, "%s:%d, TE gpio not specified\n",
+			 __func__, __LINE__);
+	}
 	/* turn off sleep mode */
 	write_reg(par, MIPI_DCS_EXIT_SLEEP_MODE);
 	mdelay(120);
@@ -137,6 +173,10 @@ static int init_display(struct fbtft_par *par)
 	 */
 	write_reg(par, PWCTRL1, 0xA4, 0xA1);
 
+	/* tearing effect line on */
+	if (par->gpio.te)
+		write_reg(par, 0x35, 0x00);
+
 	write_reg(par, MIPI_DCS_SET_DISPLAY_ON);
 
 	if (HSD20_IPS)
@@ -146,6 +186,81 @@ static int init_display(struct fbtft_par *par)
 }
 
 /**
+ * st7789v_write_vmem16_bus8() -  write data to display
+ *
+ * @par: FBTFT parameter object
+ * @offset: offset from screen_buffer
+ * @len: the length of data to be written
+ *
+ * 16 bit pixel over 8-bit databus
+ *
+ * Return: 0 on success, < 0 if error occurred.
+ */
+
+static int st7789v_write_vmem16_bus8(struct fbtft_par *par, size_t offset, size_t len)
+{
+	u16 *vmem16;
+	__be16 *txbuf16 = par->txbuf.buf;
+	size_t remain;
+	size_t to_copy;
+	size_t tx_array_size;
+	int i;
+	int ret = 0;
+	size_t startbyte_size = 0;
+
+	fbtft_par_dbg(DEBUG_WRITE_VMEM, par, "st7789v ---%s(offset=%zu, len=%zu)\n",
+		      __func__, offset, len);
+
+	remain = len / 2;
+	vmem16 = (u16 *)(par->info->screen_buffer + offset);
+
+	if (par->gpio.dc)
+		gpiod_set_value(par->gpio.dc, 1);
+
+	if (par->gpio.te) {
+		enable_irq(gpiod_to_irq(par->gpio.te));
+		reinit_completion(&spi_panel_te);
+		ret = wait_for_completion_timeout(&spi_panel_te,
+						  msecs_to_jiffies(SPI_PANEL_TE_TIMEOUT));
+		if (ret == 0)
+			dev_err(par->info->device, "wait panel TE time out\n");
+
+		disable_irq(gpiod_to_irq(par->gpio.te));
+	}
+	/* non buffered write */
+	if (!par->txbuf.buf)
+		return par->fbtftops.write(par, vmem16, len);
+
+	/* buffered write */
+	tx_array_size = par->txbuf.len / 2;
+
+	if (par->startbyte) {
+		txbuf16 = par->txbuf.buf + 1;
+		tx_array_size -= 2;
+		*(u8 *)(par->txbuf.buf) = par->startbyte | 0x2;
+		startbyte_size = 1;
+	}
+
+	while (remain) {
+		to_copy = min(tx_array_size, remain);
+		dev_dbg(par->info->device, "    to_copy=%zu, remain=%zu\n",
+			to_copy, remain - to_copy);
+
+		for (i = 0; i < to_copy; i++)
+			txbuf16[i] = cpu_to_be16(vmem16[i]);
+
+		vmem16 = vmem16 + to_copy;
+		ret = par->fbtftops.write(par, par->txbuf.buf,
+					 startbyte_size + to_copy * 2);
+		if (ret < 0)
+			return ret;
+		remain -= to_copy;
+	}
+
+	return ret;
+}
+
+/**
  * set_var() - apply LCD properties like rotation and BGR mode
  *
  * @par: FBTFT parameter object
@@ -259,6 +374,7 @@ static int blank(struct fbtft_par *par, bool on)
 	.gamma = HSD20_IPS_GAMMA,
 	.fbtftops = {
 		.init_display = init_display,
+		.write_vmem = st7789v_write_vmem16_bus8,
 		.set_var = set_var,
 		.set_gamma = set_gamma,
 		.blank = blank,
diff --git a/drivers/staging/fbtft/fbtft.h b/drivers/staging/fbtft/fbtft.h
index 76f8c09..93bac05 100644
--- a/drivers/staging/fbtft/fbtft.h
+++ b/drivers/staging/fbtft/fbtft.h
@@ -212,6 +212,7 @@ struct fbtft_par {
 		struct gpio_desc *wr;
 		struct gpio_desc *latch;
 		struct gpio_desc *cs;
+		struct gpio_desc *te;
 		struct gpio_desc *db[16];
 		struct gpio_desc *led[16];
 		struct gpio_desc *aux[16];
-- 
1.9.1