linux-kernel - [PATCH v2 8/9] regulator/rpi-panel-attiny: Don't read the LCD power status

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Date:   Fri, 21 Jan 2022 10:20:55 -0500
From:   Detlev Casanova <detlev.casanova@...labora.com>
To:     linux-kernel@...r.kernel.org
Cc:     Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Subject: [PATCH v2 8/9] regulator/rpi-panel-attiny: Don't read the LCD power status

From: Dave Stevenson <dave.stevenson@...pberrypi.com>

The I2C to the Atmel is very fussy, and locks up easily on
Pi0-3 particularly on reads.

The LCD power status is controlled solely by this driver, so
rather than reading it back from the Atmel, use the cached
status last set.

Signed-off-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
---
 drivers/regulator/rpi-panel-attiny-regulator.c | 18 +-----------------
 1 file changed, 1 insertion(+), 17 deletions(-)

diff --git a/drivers/regulator/rpi-panel-attiny-regulator.c b/drivers/regulator/rpi-panel-attiny-regulator.c
index 8090b9a485b5..8b80c0de1022 100644
--- a/drivers/regulator/rpi-panel-attiny-regulator.c
+++ b/drivers/regulator/rpi-panel-attiny-regulator.c
@@ -144,24 +144,8 @@ static int attiny_lcd_power_disable(struct regulator_dev *rdev)
 static int attiny_lcd_power_is_enabled(struct regulator_dev *rdev)
 {
 	struct attiny_lcd *state = rdev_get_drvdata(rdev);
-	unsigned int data;
-	int ret, i;
-
-	mutex_lock(&state->lock);
-
-	for (i = 0; i < 10; i++) {
-		ret = regmap_read(rdev->regmap, REG_PORTC, &data);
-		if (!ret)
-			break;
-		usleep_range(10000, 12000);
-	}
-
-	mutex_unlock(&state->lock);
-
-	if (ret < 0)
-		return ret;
 
-	return data & PC_RST_BRIDGE_N;
+	return state->port_states[REG_PORTC - REG_PORTA] & PC_RST_BRIDGE_N;
 }
 
 static const struct regulator_init_data attiny_regulator_default = {
-- 
2.34.1