gnss: sirf: fix synchronous write timeout

commit 1decef37 upstream.

Passing a timeout of zero to the synchronous serdev_device_write()
helper does currently not imply to wait forever (unlike passing zero to
serdev_device_wait_until_sent()). Instead, if there's insufficient
room in the write buffer, we'd end up with an incomplete write.

Fixes: d2efbbd1 ("gnss: add driver for sirfstar-based receivers")
Cc: stable <stable@vger.kernel.org>     # 4.19
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gnss/sirf.c

@@ -16,6 +16,7 @@
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
+#include <linux/sched.h>
 #include <linux/serdev.h>
 #include <linux/slab.h>
 #include <linux/wait.h>
@@ -83,7 +84,7 @@ static int sirf_write_raw(struct gnss_device *gdev, const unsigned char *buf,
 	int ret;
 
 	/* write is only buffered synchronously */
-	ret = serdev_device_write(serdev, buf, count, 0);
+	ret = serdev_device_write(serdev, buf, count, MAX_SCHEDULE_TIMEOUT);
 	if (ret < 0)
 		return ret;