From 480c8e9f48f8a96c457eb3dc0079a73598fb7477 Mon Sep 17 00:00:00 2001 From: Nick Hollinghurst 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);