Re: USB serial regression 2.6.31.1 -> 2.6.31.2 [PATCH]
From: Benjamin Herrenschmidt
Date: Tue Oct 13 2009 - 00:56:04 EST
usb-storage: Workaround devices with bogus sense size
Some devices, such as Huawei E169, advertise more than the standard
amount of sense data, causing us to set US_FL_SANE_SENSE, assuming
they support it. However, they subsequently fail the request sense
with that size.
This works around it generically. When a sense request fails due to
a device returning an error, US_FL_SANE_SENSE was set, and that sense
request used a larger sense size, we retry with a smaller size before
giving up.
Based on an original patch by Ben Efros <ben@xxxxxxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
---
This should also be applied to 2.6.31 stable
diff -urN linux-source-2.6.31-11-benh/drivers/usb/storage/transport.c linux-source-2.6.31-12-benh/drivers/usb/storage/transport.c
--- linux-source-2.6.31-11-benh/drivers/usb/storage/transport.c 2009-09-10 08:13:59.000000000 +1000
+++ linux-source-2.6.31-12-benh/drivers/usb/storage/transport.c 2009-10-13 15:44:57.117722653 +1100
@@ -696,7 +696,7 @@
/* device supports and needs bigger sense buffer */
if (us->fflags & US_FL_SANE_SENSE)
sense_size = ~0;
-
+Retry_Sense:
US_DEBUGP("Issuing auto-REQUEST_SENSE\n");
scsi_eh_prep_cmnd(srb, &ses, NULL, 0, sense_size);
@@ -720,6 +720,21 @@
srb->result = DID_ABORT << 16;
goto Handle_Errors;
}
+
+ /* Some devices claim to support larger sense but fail when
+ * trying to request it. When a transport failure happens
+ * using US_FS_SANE_SENSE, we always retry with a standard
+ * (small) sense request. This fixes some USB GSM modems
+ */
+ if (temp_result == USB_STOR_TRANSPORT_FAILED &&
+ (us->fflags & US_FL_SANE_SENSE) &&
+ sense_size != US_SENSE_SIZE) {
+ US_DEBUGP("-- auto-sense failure, retry small sense\n");
+ sense_size = US_SENSE_SIZE;
+ goto Retry_Sense;
+ }
+
+ /* Other failures */
if (temp_result != USB_STOR_TRANSPORT_GOOD) {
US_DEBUGP("-- auto-sense failure\n");
--
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