From: Carlis zhangxuezhi1@yulong.com
For st7789v IC, when we need continuous full screen refresh, it is best to wait for the tearing effect line signal to arrive to avoid screen tearing.
Signed-off-by: Carlis zhangxuezhi1@yulong.com --- v15: change ret value return logic in write_vmem. v14: change to define TE completion and TE irq only in st7789v. v13: change TE completion to par data struct member and add a new function to deal te gpio request, add new write_vmem function. 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 | 115 +++++++++++++++++++++++++++++++++++++ 1 file changed, 115 insertions(+)
diff --git a/drivers/staging/fbtft/fb_st7789v.c b/drivers/staging/fbtft/fb_st7789v.c index 3a280cc..abe9395 100644 --- a/drivers/staging/fbtft/fb_st7789v.c +++ b/drivers/staging/fbtft/fb_st7789v.c @@ -7,9 +7,13 @@
#include <linux/bitops.h> #include <linux/delay.h> +#include <linux/gpio/consumer.h> #include <linux/init.h> #include <linux/kernel.h> +#include <linux/interrupt.h> +#include <linux/completion.h> #include <linux/module.h> + #include <video/mipi_display.h>
#include "fbtft.h" @@ -66,6 +70,62 @@ enum st7789v_command { #define MADCTL_MX BIT(6) /* bitmask for column address order */ #define MADCTL_MY BIT(7) /* bitmask for page address order */
+/* 60Hz for 16.6ms, configured as 2*16.6ms */ +#define PANEL_TE_TIMEOUT_MS 33 + +static struct completion panel_te; /* completion for panel TE line */ +static int irq_te; /* Linux IRQ for LCD TE line */ + +static irqreturn_t panel_te_handler(int irq, void *data) +{ + complete(&panel_te); + return IRQ_HANDLED; +} + +/* + * init_tearing_effect_line() - init tearing effect line. + * @par: FBTFT parameter object. + * + * Return: 0 on success, or a negative error code otherwise. + */ +static int init_tearing_effect_line(struct fbtft_par *par) +{ + struct device *dev = par->info->device; + struct gpio_desc *te; + int rc, irq; + + te = gpiod_get_optional(dev, "te", GPIOD_IN); + if (IS_ERR(te)) + return dev_err_probe(dev, PTR_ERR(te), "Failed to request te GPIO\n"); + + /* if te is NULL, indicating no configuration, directly return success */ + if (!te) { + irq_te = 0; + return 0; + } + + irq = gpiod_to_irq(te); + + /* GPIO is locked as an IRQ, we may drop the reference */ + gpiod_put(te); + + if (irq < 0) + return irq; + + irq_te = irq; + init_completion(&panel_te); + + /* The effective state is high and lasts no more than 1000 microseconds */ + rc = devm_request_irq(dev, irq_te, panel_te_handler, + IRQF_TRIGGER_RISING, "TE_GPIO", par); + if (rc) + return dev_err_probe(dev, rc, "TE IRQ request failed.\n"); + + disable_irq_nosync(irq_te); + + return 0; +} + /** * init_display() - initialize the display controller * @@ -82,6 +142,12 @@ enum st7789v_command { */ static int init_display(struct fbtft_par *par) { + int rc; + + rc = init_tearing_effect_line(par); + if (rc) + return rc; + /* turn off sleep mode */ write_reg(par, MIPI_DCS_EXIT_SLEEP_MODE); mdelay(120); @@ -137,6 +203,10 @@ static int init_display(struct fbtft_par *par) */ write_reg(par, PWCTRL1, 0xA4, 0xA1);
+ /* TE line output is off by default when powering on */ + if (irq_te) + write_reg(par, MIPI_DCS_SET_TEAR_ON, 0x00); + write_reg(par, MIPI_DCS_SET_DISPLAY_ON);
if (HSD20_IPS) @@ -145,6 +215,50 @@ static int init_display(struct fbtft_par *par) return 0; }
+/* + * write_vmem() - write data to display. + * @par: FBTFT parameter object. + * @offset: offset from screen_buffer. + * @len: the length of data to be writte. + * + * Return: 0 on success, or a negative error code otherwise. + */ +static int write_vmem(struct fbtft_par *par, size_t offset, size_t len) +{ + struct device *dev = par->info->device; + int ret; + + if (irq_te) { + enable_irq(irq_te); + reinit_completion(&panel_te); + ret = wait_for_completion_timeout(&panel_te, + msecs_to_jiffies(PANEL_TE_TIMEOUT_MS)); + if (ret == 0) + dev_err(dev, "wait panel TE timeout\n"); + + disable_irq(irq_te); + } + + switch (par->pdata->display.buswidth) { + case 8: + ret = fbtft_write_vmem16_bus8(par, offset, len); + break; + case 9: + ret = fbtft_write_vmem16_bus9(par, offset, len); + break; + case 16: + ret = fbtft_write_vmem16_bus16(par, offset, len); + break; + default: + dev_err(dev, "Unsupported buswidth %d\n", + par->pdata->display.buswidth); + ret = 0; + break; + } + + return ret; +} + /** * set_var() - apply LCD properties like rotation and BGR mode * @@ -259,6 +373,7 @@ static int blank(struct fbtft_par *par, bool on) .gamma = HSD20_IPS_GAMMA, .fbtftops = { .init_display = init_display, + .write_vmem = write_vmem, .set_var = set_var, .set_gamma = set_gamma, .blank = blank,