USB: otg/ulpi: bail out on read errors

otg_read may return errnos, so bail out correctly to prevent bogus
ID-numbers.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Daniel Mack <daniel@caiaq.de>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 6 deletions

diff --git a/drivers/usb/otg/ulpi.c b/drivers/usb/otg/ulpi.c
index b1b346932946..d331b222ad21 100644
--- a/drivers/usb/otg/ulpi.c
+++ b/drivers/usb/otg/ulpi.c
@@ -59,12 +59,17 @@ static int ulpi_set_flags(struct otg_transceiver *otg)
 
 static int ulpi_init(struct otg_transceiver *otg)
 {
-        int i, vid, pid;
-
-        vid = (otg_io_read(otg, ULPI_VENDOR_ID_HIGH) << 8) |
-               otg_io_read(otg, ULPI_VENDOR_ID_LOW);
-        pid = (otg_io_read(otg, ULPI_PRODUCT_ID_HIGH) << 8) |
-               otg_io_read(otg, ULPI_PRODUCT_ID_LOW);
+        int i, vid, pid, ret;
+        u32 ulpi_id = 0;
+
+        for (i = 0; i < 4; i++) {
+                ret = otg_io_read(otg, ULPI_PRODUCT_ID_HIGH - i);
+                if (ret < 0)
+                        return ret;
+                ulpi_id = (ulpi_id << 8) | ret;
+        }
+        vid = ulpi_id & 0xffff;
+        pid = ulpi_id >> 16;
 
         pr_info("ULPI transceiver vendor/product ID 0x%04x/0x%04x\n", vid, pid);