diff options
Diffstat (limited to 'target/linux/bcm27xx/patches-5.10/950-0382-drm-panel-raspberrypi-touchscreen-Use-independent-I2.patch')
| -rw-r--r-- | target/linux/bcm27xx/patches-5.10/950-0382-drm-panel-raspberrypi-touchscreen-Use-independent-I2.patch | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-5.10/950-0382-drm-panel-raspberrypi-touchscreen-Use-independent-I2.patch b/target/linux/bcm27xx/patches-5.10/950-0382-drm-panel-raspberrypi-touchscreen-Use-independent-I2.patch new file mode 100644 index 0000000000..57aabc7e87 --- /dev/null +++ b/target/linux/bcm27xx/patches-5.10/950-0382-drm-panel-raspberrypi-touchscreen-Use-independent-I2.patch @@ -0,0 +1,58 @@ +From 3ad3a680ece56c7134d9500a0413b4f9259c07d8 Mon Sep 17 00:00:00 2001 +From: Dave Stevenson <dave.stevenson@raspberrypi.com> +Date: Thu, 23 Apr 2020 10:17:18 +0100 +Subject: [PATCH] drm/panel/raspberrypi-touchscreen: Use independent + I2C actions with delay. + +We now have the hardware I2C controller pinmuxed to the drive the +display I2C, but this controller does not support clock stretching. +The Atmel micro-controller in the panel requires clock stretching +to allow it to prepare any data to be read. + +Split the rpi_touchscreen_i2c_read into two independent transactions with +a delay between them for the Atmel to prepare the data. + +Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com> +--- + .../drm/panel/panel-raspberrypi-touchscreen.c | 30 ++++++++++++++++++- + 1 file changed, 29 insertions(+), 1 deletion(-) + +--- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c ++++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c +@@ -219,7 +219,35 @@ static struct rpi_touchscreen *panel_to_ + + static int rpi_touchscreen_i2c_read(struct rpi_touchscreen *ts, u8 reg) + { +- return i2c_smbus_read_byte_data(ts->i2c, reg); ++ struct i2c_client *client = ts->i2c; ++ 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(100, 300); ++ ++ /* 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; ++ ++ return data_buf[0]; + } + + static void rpi_touchscreen_i2c_write(struct rpi_touchscreen *ts, |