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