The data sheet for CY8CTMA340 specifies that the reset pulse
shall be at least 1 ms. Specify 1-2 ms with usleep_range()
to cut some slack for the scheduler.
Curiously the datasheet does not specify how long we have to
wait after a hard reset until the chip is up, but I have found
a vendor tree (Samsung GT-S7710) that has code for this touch
screen and there this is set to 5 ms so I use this with
the same 1 ms fuzz.
Reviewed-by: Javier Martinez Canillas <javier@xxxxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
ChangeLog v1->v3:
- Collect Javier's Reviewed-by
---
drivers/input/touchscreen/cyttsp_core.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/input/touchscreen/cyttsp_core.c b/drivers/input/touchscreen/cyttsp_core.c
index 91f8f38b3f06..84f4f1c1a220 100644
--- a/drivers/input/touchscreen/cyttsp_core.c
+++ b/drivers/input/touchscreen/cyttsp_core.c
@@ -230,10 +230,16 @@ static int cyttsp_set_sysinfo_regs(struct cyttsp *ts)
static void cyttsp_hard_reset(struct cyttsp *ts)
{
if (ts->reset_gpio) {
+ /*
+ * According to the CY8CTMA340 datasheet page 21, the external
+ * reset pulse width should be >= 1 ms. The datasheet does not
+ * specify how long we have to wait after reset but a vendor
+ * tree specifies 5 ms here.
+ */
gpiod_set_value_cansleep(ts->reset_gpio, 1);
- msleep(CY_DELAY_DFLT);
+ usleep_range(1000, 2000);
gpiod_set_value_cansleep(ts->reset_gpio, 0);
- msleep(CY_DELAY_DFLT);
+ usleep_range(5000, 6000);
}
}
--
2.29.2
