On an Advantech MICA-071 tablet, with a builtin barcode scanner connected
to ttyS0, the following message is shown on suspend:
serial 00:02: disabled
And after suspend/resume trying to use the barcode scanner / ttyS0 shows:
serial 00:02: LSR safety check engaged!
Indicating that the UARTs io-ports are no longer reachable.
This is caused by __pnp_bus_suspend() calling pnp_stop_dev() on the "00:02"
pnp device on suspend (this outputs the disabled message).
The problem is that pnp_can_write() returns false for the "00:02" pnp
device, so after disabling it (disabling its decoding of IO addresses)
during suspend, it cannot be re-enabled.
Add a pnp_can_write() check to the suspend path and only disable devices
which can actually be re-enabled on resume.
This fixes the Advantech MICA-071's ttyS0 no longer working after
a suspend/resume.
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
drivers/pnp/driver.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/pnp/driver.c b/drivers/pnp/driver.c
index c02e7bf643a6..46c534f6b1c9 100644
--- a/drivers/pnp/driver.c
+++ b/drivers/pnp/driver.c
@@ -182,7 +182,8 @@ static int __pnp_bus_suspend(struct device *dev, pm_message_t state)
return error;
}
- if (pnp_can_disable(pnp_dev)) {
+ /* can_write is necessary to be able to re-start the device on resume */
+ if (pnp_can_disable(pnp_dev) && pnp_can_write(pnp_dev)) {
error = pnp_stop_dev(pnp_dev);
if (error)
return error;
--
2.38.1
