1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
|
From 480c8e9f48f8a96c457eb3dc0079a73598fb7477 Mon Sep 17 00:00:00 2001
From: Nick Hollinghurst <nick.hollinghurst@raspberrypi.org>
Date: Wed, 1 Dec 2021 19:43:08 +0000
Subject: [PATCH] drm/panel/raspberrypi-touchscreen: Insert more delays.
This avoids failures in cases where the panel is enabled
or re-probed very soon after being disabled or probed.
These can occur because the Atmel device can mis-behave
over I2C for a few ms after any write to the POWERON register.
---
drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
+++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
@@ -299,6 +299,13 @@ static int rpi_touchscreen_prepare(struc
struct rpi_touchscreen *ts = panel_to_ts(panel);
int i, data;
+ /*
+ * Power up the Toshiba bridge. The Atmel device can misbehave
+ * over I2C for a few ms after writes to REG_POWERON (including the
+ * write in rpi_touchscreen_disable()), so sleep before and after.
+ * Also to ensure that the bridge has been off for at least 100ms.
+ */
+ msleep(100);
rpi_touchscreen_i2c_write(ts, REG_POWERON, 1);
usleep_range(20000, 25000);
/* Wait for nPWRDWN to go low to indicate poweron is done. */
@@ -431,6 +438,7 @@ static int rpi_touchscreen_probe(struct
/* Turn off at boot, so we can cleanly sequence powering on. */
rpi_touchscreen_i2c_write(ts, REG_POWERON, 0);
+ usleep_range(20000, 25000);
/* Look up the DSI host. It needs to probe before we do. */
endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
|