On Wed, 18 Dec 2013, Daniel Mack wrote: > Hi, > > I'm facing an issue putting an embedded system to sleep while a Lacie > external USB hard disk is connected. Relevant kernel messages that occur > at the attempt are: > > [ 13.834731] PM: Sending message for entering DeepSleep mode > [ 13.846575] sd 0:0:0:0: [sda] Synchronizing SCSI cache > [ 13.858818] sd 0:0:0:0: [sda] > [ 13.862432] Result: hostbyte=0x00 driverbyte=0x08 > [ 13.867349] sd 0:0:0:0: [sda] > [ 13.870626] Sense Key : 0x5 [current] > [ 13.874602] sd 0:0:0:0: [sda] > [ 13.877879] ASC=0x20 ASCQ=0x0 > [ 13.885053] dpm_run_callback(): scsi_bus_suspend+0x0/0x20 returns -5 > [ 13.901130] PM: Device 0:0:0:0 failed to suspend async: error -5 > [ 13.907507] PM: Some devices failed to suspend, or early wake event > detected > > What happens is that in sd_sync_cache(), scsi_execute_req_flags() > returns 0x08000002, so driver_byte(res) evaluates to DRIVER_SENSE and > host_byte(res) is DID_OK, which is an unhandled case that leads to -EIO > eventually. > > I have admittedly not much clue about the SCSI layer, so I wonder what > would be the best way to fix this. Should DID_OK just be handled as > non-error condition in the switch? Should the suspend call chain ignore > such errors from sd_sync_cache()? > > I'm open to suggestions and happy to test patches. The Sense Key and ASC values indicate that the drive did not understand the SYNCHRONIZE CACHE command. A usbmon trace would verify this; see the instructions in Documentation/usb/usbmon.txt. Assuming that really is what happened, we have to decide how to handle the situation. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
