openwrt/target/linux/bcm27xx/patches-6.6/950-1092-regulator-rpi_panel_v2-Add-delay-on-I2C-reads.patch
Álvaro Fernández Rojas 8c405cdccc bcm27xx: add 6.6 kernel patches
The patches were generated from the RPi repo with the following command:
git format-patch v6.6.34..rpi-6.1.y

Some patches needed rebasing and, as usual, the applied and reverted, wireless
drivers, Github workflows, READMEs and defconfigs patches were removed.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
2024-06-18 18:52:49 +02:00

71 lines
2.1 KiB
Diff

From f1a2a9a675899c166a75c6e398af8aa5445e5e5f Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Fri, 17 May 2024 14:27:59 +0100
Subject: [PATCH 1092/1135] regulator: rpi_panel_v2: Add delay on I2C reads
As with many microcontrollers, the panel wants to use clock
stretching during a read so that the appropriate return value
can be generated and programmed into the hardware.
With Pi0-3 really not supporting clock stretching, this resulted
in the panel firmware dying.
Insert a delay between the write and the read to give the firmware
a chance to generate the relevant return value.
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
drivers/regulator/rpi-panel-v2-regulator.c | 35 +++++++++++++++++++++-
1 file changed, 34 insertions(+), 1 deletion(-)
--- a/drivers/regulator/rpi-panel-v2-regulator.c
+++ b/drivers/regulator/rpi-panel-v2-regulator.c
@@ -87,6 +87,39 @@ static const struct backlight_ops rpi_pa
.update_status = rpi_panel_v2_update_status,
};
+static int rpi_panel_v2_i2c_read(struct i2c_client *client, u8 reg, unsigned int *buf)
+{
+ struct i2c_msg msgs[1];
+ u8 addr_buf[1] = { reg };
+ u8 data_buf[1] = { 0, };
+ int ret;
+
+ /* Write register address */
+ msgs[0].addr = client->addr;
+ msgs[0].flags = 0;
+ msgs[0].len = ARRAY_SIZE(addr_buf);
+ msgs[0].buf = addr_buf;
+
+ ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+ if (ret != ARRAY_SIZE(msgs))
+ return -EIO;
+
+ usleep_range(5000, 10000);
+
+ /* Read data from register */
+ msgs[0].addr = client->addr;
+ msgs[0].flags = I2C_M_RD;
+ msgs[0].len = 1;
+ msgs[0].buf = data_buf;
+
+ ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+ if (ret != ARRAY_SIZE(msgs))
+ return -EIO;
+
+ *buf = data_buf[0];
+ return 0;
+}
+
/*
* I2C driver interface functions
*/
@@ -114,7 +147,7 @@ static int rpi_panel_v2_i2c_probe(struct
goto error;
}
- ret = regmap_read(regmap, REG_ID, &data);
+ ret = rpi_panel_v2_i2c_read(i2c, REG_ID, &data);
if (ret < 0) {
dev_err(&i2c->dev, "Failed to read REG_ID reg: %d\n", ret);
goto error;