drivers: uc81xx: Add workaround for chips without autocopy

The UC8176 doesn't automatically copy writes to the buffer containing
the old SRAM contents. In this case, we need to manually copy data to
the back buffer.

Signed-off-by: Andreas Sandberg <[email protected]>

Author: andysan

drivers/display/uc81xx.c

@@ -63,6 +63,8 @@ struct uc81xx_quirks {
 	uint16_t max_width;
 	uint16_t max_height;
 
+	bool auto_copy;
+
 	int (*set_cdi)(const struct device *dev, bool border);
 };
 
@@ -409,6 +411,8 @@ static int uc81xx_write(const struct device *dev, const uint16_t x, const uint16
 		.flags = UC81XX_PTL_FLAG_PT_SCAN,
 	};
 	size_t buf_len;
+	const uint8_t back_buffer = data->blanking_on ?
+		UC81XX_CMD_DTM1 : UC81XX_CMD_DTM2;
 
 	LOG_DBG("x %u, y %u, height %u, width %u, pitch %u",
 		x, y, desc->height, desc->width, desc->pitch);
@@ -477,6 +481,23 @@ static int uc81xx_write(const struct device *dev, const uint16_t x, const uint16
 		}
 	}
 
+	if (!config->quirks->auto_copy) {
+		/* Some controllers don't copy the new data to the old
+		 * data buffer on refresh. Do that manually here if
+		 * needed.
+		 */
+
+		if (uc81xx_write_cmd(dev, UC81XX_CMD_PTL,
+				     (const void *)&ptl, sizeof(ptl))) {
+			return -EIO;
+		}
+
+		if (uc81xx_write_cmd(dev, back_buffer,
+				     (uint8_t *)buf, buf_len)) {
+			return -EIO;
+		}
+	}
+
 	if (uc81xx_write_cmd(dev, UC81XX_CMD_PTOUT, NULL, 0)) {
 		return -EIO;
 	}
@@ -659,6 +680,8 @@ static const struct uc81xx_quirks uc8176_quirks = {
 	.max_width = 400,
 	.max_height = 300,
 
+	.auto_copy = false,
+
 	.set_cdi = uc8176_set_cdi,
 };
 #endif
@@ -688,6 +711,8 @@ static const struct uc81xx_quirks uc8179_quirks = {
 	.max_width = 800,
 	.max_height = 600,
 
+	.auto_copy = true,
+
 	.set_cdi = uc8179_set_cdi,
 };
 #endif