Patch "regulator: rpi-panel: Handle I2C errors/timing to the Atmel" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    regulator: rpi-panel: Handle I2C errors/timing to the Atmel

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     regulator-rpi-panel-handle-i2c-errors-timing-to-the-.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit bdddb998251b74b4c9590410f852fd56be749ceb
Author: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
Date:   Mon Jan 24 17:01:22 2022 -0500

    regulator: rpi-panel: Handle I2C errors/timing to the Atmel
    
    [ Upstream commit 5665eee7a3800430e7dc3ef6f25722476b603186 ]
    
    The Atmel is doing some things in the I2C ISR, during which
    period it will not respond to further commands. This is
    particularly true of the POWERON command.
    
    Increase delays appropriately, and retry should I2C errors be
    reported.
    
    Signed-off-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
    Signed-off-by: Detlev Casanova <detlev.casanova@xxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20220124220129.158891-3-detlev.casanova@xxxxxxxxxxxxx
    Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/regulator/rpi-panel-attiny-regulator.c b/drivers/regulator/rpi-panel-attiny-regulator.c
index ee46bfbf5eee..991b4730d768 100644
--- a/drivers/regulator/rpi-panel-attiny-regulator.c
+++ b/drivers/regulator/rpi-panel-attiny-regulator.c
@@ -37,11 +37,24 @@ static const struct regmap_config attiny_regmap_config = {
 static int attiny_lcd_power_enable(struct regulator_dev *rdev)
 {
 	unsigned int data;
+	int ret, i;
 
 	regmap_write(rdev->regmap, REG_POWERON, 1);
+	msleep(80);
+
 	/* Wait for nPWRDWN to go low to indicate poweron is done. */
-	regmap_read_poll_timeout(rdev->regmap, REG_PORTB, data,
-					data & BIT(0), 10, 1000000);
+	for (i = 0; i < 20; i++) {
+		ret = regmap_read(rdev->regmap, REG_PORTB, &data);
+		if (!ret) {
+			if (data & BIT(0))
+				break;
+		}
+		usleep_range(10000, 12000);
+	}
+	usleep_range(10000, 12000);
+
+	if (ret)
+		pr_err("%s: regmap_read_poll_timeout failed %d\n", __func__, ret);
 
 	/* Default to the same orientation as the closed source
 	 * firmware used for the panel.  Runtime rotation
@@ -57,23 +70,34 @@ static int attiny_lcd_power_disable(struct regulator_dev *rdev)
 {
 	regmap_write(rdev->regmap, REG_PWM, 0);
 	regmap_write(rdev->regmap, REG_POWERON, 0);
-	udelay(1);
+	msleep(30);
 	return 0;
 }
 
 static int attiny_lcd_power_is_enabled(struct regulator_dev *rdev)
 {
 	unsigned int data;
-	int ret;
+	int ret, i;
 
-	ret = regmap_read(rdev->regmap, REG_POWERON, &data);
+	for (i = 0; i < 10; i++) {
+		ret = regmap_read(rdev->regmap, REG_POWERON, &data);
+		if (!ret)
+			break;
+		usleep_range(10000, 12000);
+	}
 	if (ret < 0)
 		return ret;
 
 	if (!(data & BIT(0)))
 		return 0;
 
-	ret = regmap_read(rdev->regmap, REG_PORTB, &data);
+	for (i = 0; i < 10; i++) {
+		ret = regmap_read(rdev->regmap, REG_PORTB, &data);
+		if (!ret)
+			break;
+		usleep_range(10000, 12000);
+	}
+
 	if (ret < 0)
 		return ret;
 
@@ -103,20 +127,32 @@ static int attiny_update_status(struct backlight_device *bl)
 {
 	struct regmap *regmap = bl_get_data(bl);
 	int brightness = bl->props.brightness;
+	int ret, i;
 
 	if (bl->props.power != FB_BLANK_UNBLANK ||
 	    bl->props.fb_blank != FB_BLANK_UNBLANK)
 		brightness = 0;
 
-	return regmap_write(regmap, REG_PWM, brightness);
+	for (i = 0; i < 10; i++) {
+		ret = regmap_write(regmap, REG_PWM, brightness);
+		if (!ret)
+			break;
+	}
+
+	return ret;
 }
 
 static int attiny_get_brightness(struct backlight_device *bl)
 {
 	struct regmap *regmap = bl_get_data(bl);
-	int ret, brightness;
+	int ret, brightness, i;
+
+	for (i = 0; i < 10; i++) {
+		ret = regmap_read(regmap, REG_PWM, &brightness);
+		if (!ret)
+			break;
+	}
 
-	ret = regmap_read(regmap, REG_PWM, &brightness);
 	if (ret)
 		return ret;
 
@@ -166,7 +202,7 @@ static int attiny_i2c_probe(struct i2c_client *i2c,
 	}
 
 	regmap_write(regmap, REG_POWERON, 0);
-	mdelay(1);
+	msleep(30);
 
 	config.dev = &i2c->dev;
 	config.regmap = regmap;