git.openwrt.org Git - openwrt/staging/xback.git/blob

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