From: Luca Ellero l.ellero@asem.it
[ Upstream commit 13f82ca3878db8284a70ef9711d7f710a31eb562 ]
Controllers that report pressure (e.g. ADS7846) use 5 commands and the correct sequence is READ_X, READ_Y, READ_Z1, READ_Z2, PWRDOWN.
Controllers that don't report pressure (e.g. ADS7845/ADS7843) use only 3 commands and the correct sequence should be READ_X, READ_Y, PWRDOWN. But the sequence sent was incorrect: READ_X, READ_Y, READ_Z1.
Fix this by setting the third (and last) command to PWRDOWN.
Fixes: ffa458c1bd9b ("spi: ads7846 driver") Signed-off-by: Luca Ellero l.ellero@asem.it Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com Link: https://lore.kernel.org/r/20230126105227.47648-3-l.ellero@asem.it Signed-off-by: Dmitry Torokhov dmitry.torokhov@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/input/touchscreen/ads7846.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c index 0610fab5ed93b..9f5cc42a567a5 100644 --- a/drivers/input/touchscreen/ads7846.c +++ b/drivers/input/touchscreen/ads7846.c @@ -1075,6 +1075,9 @@ static int ads7846_setup_spi_msg(struct ads7846 *ts, struct ads7846_buf_layout *l = &packet->l[cmd_idx]; unsigned int max_count;
+ if (cmd_idx == packet->cmds - 1) + cmd_idx = ADS7846_PWDOWN; + if (ads7846_cmd_need_settle(cmd_idx)) max_count = packet->count + packet->count_skip; else @@ -1111,7 +1114,12 @@ static int ads7846_setup_spi_msg(struct ads7846 *ts,
for (cmd_idx = 0; cmd_idx < packet->cmds; cmd_idx++) { struct ads7846_buf_layout *l = &packet->l[cmd_idx]; - u8 cmd = ads7846_get_cmd(cmd_idx, vref); + u8 cmd; + + if (cmd_idx == packet->cmds - 1) + cmd_idx = ADS7846_PWDOWN; + + cmd = ads7846_get_cmd(cmd_idx, vref);
for (b = 0; b < l->count; b++) packet->tx[l->offset + b].cmd = cmd;