From: Hans de Goede <hdego...@redhat.com> The response iu struct before this patch has a size of 7 bytes (discounting padding), which is weird since all other iu-s are explictly padded to a multiple of 4 bytes.
More over submitting a 7 byte bulk transfer to the status endpoint when expecting a response iu results in an USB babble error, as the device actually sends 8 bytes. Up on closer reading of the UAS spec: http://www.t10.org/cgi-bin/ac.pl?t=f&f=uas2r00.pdf The reason for this becomes clear, the 2 entries in "Table 17 — RESPONSE IU" are numbered 4 and 6, looking at other iu definitions in the spec, esp. multi-byte fields, this indicates that the ADDITIONAL RESPONSE INFORMATION field is not a 2 byte field as one might assume at a first look, but is a multi-byte field containing 3 bytes. This also aligns with the SCSI Architecture Model 4 spec, which UAS is based on which states in paragraph "7.1 Task management function procedure calls" that the "Additional Response Information" output argument for a Task management function procedure call is 3 bytes. Last but not least I've verified this by sending a logical unit reset task management call with an invalid lun to an actual uasp device, and received back a response-iu with byte 6 being 0, and byte 7 being 9, which is the responce code for an invalid iu, which confirms that the response code is being reported in byte 7 of the response iu rather then in byte 6. Things were working before despite this error in the response iu struct definition because the additional response info field is normally filled with zeros, and 0 is the response code value for success. Signed-off-by: Hans de Goede <hdego...@redhat.com> Signed-off-by: Sarah Sharp <sarah.a.sh...@linux.intel.com> --- include/linux/usb/uas.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/usb/uas.h b/include/linux/usb/uas.h index 14041780fb6c..772b66bcdd7d 100644 --- a/include/linux/usb/uas.h +++ b/include/linux/usb/uas.h @@ -83,7 +83,7 @@ struct response_iu { __u8 iu_id; __u8 rsvd1; __be16 tag; - __be16 add_response_info; + __u8 add_response_info[3]; __u8 response_code; }; -- 1.8.5.5 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
