Re: [PATCH v10] staging: fbtft: add tearing signal detect

On Thu, 28 Jan 2021 00:32:22 +0200
Kari Argillander [off-list ref] wrote:

On Wed, Jan 27, 2021 at 09:42:52PM +0800, Carlis wrote:

quoted

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

quoted

diff --git a/drivers/staging/fbtft/fb_st7789v.c

b/drivers/staging/fbtft/fb_st7789v.c index 3a280cc..cba08a8 100644

--- a/drivers/staging/fbtft/fb_st7789v.c
+++ b/drivers/staging/fbtft/fb_st7789v.c

@@ -9,9 +9,12 @@
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/mutex.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
 #include <linux/module.h>
 #include <video/mipi_display.h>
-
+#include <linux/gpio/consumer.h>  

Space after local headers. Also this should one up so all Linux
headers are group together. You agreed?

OK,i will fix it in patch v12 tomorrow

quoted

 #include "fbtft.h"
 
 #define DRVNAME "fb_st7789v"

@@ -66,6 +69,32 @@ 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 mutex te_mutex;/* mutex for set te gpio irq status

*/  

Space after ;

hi, i have fix it in the patch v11

quoted

+static struct completion spi_panel_te;  

What if multiple displays? Is this possible for user?

I will check it carefully again about this logic.

quoted

+
+static irqreturn_t spi_panel_te_handler(int irq, void *data)
+{
+	complete(&spi_panel_te);
+	return IRQ_HANDLED;
+}
+
+static void set_spi_panel_te_irq_status(struct fbtft_par *par,
bool enable) +{
+	static int te_irq_count;  

Same here. Maybe you can think better way and then this code would
also be cleaner.

quoted

+
+	mutex_lock(&te_mutex);  

So locking should be done if we really do action and not just in case.

quoted

+
+	if (enable) {
+		if (++te_irq_count == 1)
+			enable_irq(gpiod_to_irq(par->gpio.te));
+	} else {
+		if (--te_irq_count == 0)
+			disable_irq(gpiod_to_irq(par->gpio.te));
+	}
+	mutex_unlock(&te_mutex);
+}
+
 /**
  * init_display() - initialize the display controller
  *

@@ -82,6 +111,33 @@ 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)) {
+		rc = PTR_ERR(par->gpio.te);
+		dev_err(par->info->device, "Failed to request te
gpio: %d\n", rc);
+		return rc;
+	}  

You request with optinal and you still want to error out? We could
just continue and not care about that error. User will be happier if
device still works somehow.

You mean i just delete this dev_err print ?!
like this:
	par->gpio.te = devm_gpiod_get_index_optional(dev, "te",
0,GPIOD_IN); 
        if (IS_ERR(par->gpio.te))
		return PTR_ERR(par->gpio.te);

quoted

+	if (par->gpio.te) {
+		init_completion(&spi_panel_te);
+		mutex_init(&te_mutex);
+		rc = devm_request_irq(dev,
+				      gpiod_to_irq(par->gpio.te),
+				     spi_panel_te_handler,
IRQF_TRIGGER_RISING,
+				     "TE_GPIO", par);
+		if (rc) {
+			dev_err(par->info->device, "TE request_irq
failed.\n");
+			devm_gpiod_put(dev, par->gpio.te);
+			return rc;
+		}
+
+		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 +193,9 @@ static int init_display(struct fbtft_par *par)
 	 */
 	write_reg(par, PWCTRL1, 0xA4, 0xA1);
 
+    /*Tearing Effect Line On*/  

Spaces and why upcase everything?

i will fix it in patch v12 tomorrow

quoted

+	if (par->gpio.te)
+		write_reg(par, 0x35, 0x00);
 	write_reg(par, MIPI_DCS_SET_DISPLAY_ON);
 
 	if (HSD20_IPS)

@@ -145,6 +204,76 @@ static int init_display(struct fbtft_par *par)
 	return 0;
 }
 
+/*****************************************************************************
+ *
+ *   int (*write_vmem)(struct fbtft_par *par);
+ *
+

*****************************************************************************/
+  

Why this kind of function comment? Please use same as another function
comments in this file. They are atleast almoust like kernel-doc style.

i will fix it in patch v12 tomorrow

quoted

+/* 16 bit pixel over 8-bit databus */
+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);
+
+	/* 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) {  

for (remain = len / 2; remain; remain -= to_copy) {

or even use len = len / 2 if you wanna save variable.

quoted

+		to_copy = min(tx_array_size, remain);  

Care must be taken that this will not be endless loop if another is
0. I will not check this further but hopefully you have.

quoted

+		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;  

+= Or you can ++ vmem16 at the for loop but that is not so readable
sometimes with pointers.

quoted

+		if (par->gpio.te) {
+			set_spi_panel_te_irq_status(par, true);
+			reinit_completion(&spi_panel_te);
+			ret =
wait_for_completion_timeout(&spi_panel_te,
+
msecs_to_jiffies(SPI_PANEL_TE_TIMEOUT));
+			if (ret == 0)  

!ret

quoted

+				dev_err(par->info->device, "wait
panel TE time out\n");
+		}
+		ret = par->fbtftops.write(par, par->txbuf.buf,
+					 startbyte_size + to_copy
* 2);
+		if (par->gpio.te)
+			set_spi_panel_te_irq_status(par, false);
+		if (ret < 0)
+			return ret;
+		remain -= to_copy;
+	}
+
+	return ret;  

Do we want to return something over 0? If not then this can be return
0. And then you do not need to even init ret value at the beginning.

Also wait little bit like Greg sayd before sending new version.
Someone might nack about what I say or say something more.

hi, i copy fbtft_write_vmem16_bus8 from file fbtft_bus.c and modify it
,just add te wait logic, i will take more time to check this original
function.

quoted

+}
+
 /**
  * set_var() - apply LCD properties like rotation and BGR mode
  *

@@ -259,6 +388,7 @@ 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