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drivers: display: st7735r: hold CS for pixels

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Use a continuous transaction with CS kept low for the entire batch of
row address, column address and actual pixel data write.  This is
required by ST7735S and shouldn't hurt elsewhere.

Signed-off-by: David Lamparter <equinox@diac24.net>
This commit is contained in:
David Lamparter 2023-09-10 16:13:34 +02:00 • committed by Carles Cufí
commit 19113d6e8c
1 changed files with 13 additions and 9 deletions
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22
drivers/display/display_st7735r.c
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@ -182,18 +182,19 @@ static int st7735r_set_mem_area(const struct device *dev,
spi_data[0] = sys_cpu_to_be16(ram_x);
spi_data[1] = sys_cpu_to_be16(ram_x + w - 1);
ret = st7735r_transmit(dev, ST7735R_CMD_CASET, (uint8_t *)&spi_data[0], 4);
ret = st7735r_transmit_hold(dev, ST7735R_CMD_CASET, (uint8_t *)&spi_data[0], 4);
if (ret < 0) {
return ret;
}
spi_data[0] = sys_cpu_to_be16(ram_y);
spi_data[1] = sys_cpu_to_be16(ram_y + h - 1);
ret = st7735r_transmit(dev, ST7735R_CMD_RASET, (uint8_t *)&spi_data[0], 4);
ret = st7735r_transmit_hold(dev, ST7735R_CMD_RASET, (uint8_t *)&spi_data[0], 4);
if (ret < 0) {
return ret;
}
/* NB: CS still held - data transfer coming next */
return 0;
}
@ -220,7 +221,7 @@ static int st7735r_write(const struct device *dev,
desc->width, desc->height, x, y);
ret = st7735r_set_mem_area(dev, x, y, desc->width, desc->height);
if (ret < 0) {
return ret;
goto out;
}
if (desc->pitch > desc->width) {
@ -231,11 +232,11 @@ static int st7735r_write(const struct device *dev,
nbr_of_writes = 1U;
}
ret = st7735r_transmit(dev, ST7735R_CMD_RAMWR,
(void *) write_data_start,
desc->width * ST7735R_PIXEL_SIZE * write_h);
ret = st7735r_transmit_hold(dev, ST7735R_CMD_RAMWR,
(void *) write_data_start,
desc->width * ST7735R_PIXEL_SIZE * write_h);
if (ret < 0) {
return ret;
goto out;
}
tx_bufs.buffers = &tx_buf;
@ -247,13 +248,16 @@ static int st7735r_write(const struct device *dev,
tx_buf.len = desc->width * ST7735R_PIXEL_SIZE * write_h;
ret = spi_write_dt(&config->bus, &tx_bufs);
if (ret < 0) {
return ret;
goto out;
}
write_data_start += (desc->pitch * ST7735R_PIXEL_SIZE);
}
return 0;
ret = 0;
out:
spi_release_dt(&config->bus);
return ret;
}
static void *st7735r_get_framebuffer(const struct device *dev)