Hi Alan, On 01/15/2014 06:19 PM, Alan Stern wrote: > On Wed, 15 Jan 2014, Daniel Mack wrote: > >> Hi, >> >> Sorry for the long, primarily holiday-related delay on this. >> >> On 12/18/2013 09:46 PM, Alan Stern wrote: >>> On Wed, 18 Dec 2013, Daniel Mack wrote: >>>> 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. >> >> Ok, this is the usbmon trace that I captured when the system goes to >> suspend with the USB storage media connected but unmounted: >> >> cebe5e00 3629314504 S Bo:1:003:2 -115 31 = 55534243 10000000 00000000 >> 00000a35 00000000 00000000 00000000 000000 >> cebe5e00 3629315214 C Bo:1:003:2 0 31 > >> cebe5e00 3629315413 S Bi:1:003:1 -115 13 < >> cebe5e00 3629315492 C Bi:1:003:1 0 13 = 55534253 10000000 00000000 01 > > That's the SYNCHRONIZE CACHE command, with an error return status. > >> cebe5e00 3629315571 S Bo:1:003:2 -115 31 = 55534243 11000000 12000000 >> 80000603 00000012 00000000 00000000 000000 >> cebe5e00 3629315606 C Bo:1:003:2 0 31 > >> cecd4580 3629315681 S Bi:1:003:1 -115 18 < >> cecd4580 3629315744 C Bi:1:003:1 0 18 = 70000500 0000000a 00000000 >> 20000000 0000 >> cebe5e00 3629315772 S Bi:1:003:1 -115 13 < >> cebe5e00 3629315817 C Bi:1:003:1 0 13 = 55534253 11000000 00000000 00 > > And that's the sense data, confirming SK=5 and ASC=20. This means the > drive doesn't understand the command. Ok. > There's more stuff later on in the usbmon trace that I don't > understand. But if everything else works okay, it won't matter. The host controller tried to reset the port and the device, whatever that results in. You're right, that is unrelated. > I don't think that is the right thing to do. Try this patch instead. [...] > Index: usb-3.13/drivers/scsi/sd.c > =================================================================== > --- usb-3.13.orig/drivers/scsi/sd.c > +++ usb-3.13/drivers/scsi/sd.c > @@ -1463,8 +1463,8 @@ static int sd_sync_cache(struct scsi_dis > sd_print_sense_hdr(sdkp, &sshdr); > /* we need to evaluate the error return */ > if (scsi_sense_valid(&sshdr) && > - /* 0x3a is medium not present */ > - sshdr.asc == 0x3a) > + (sshdr.asc == 0x3a || /* medium not present */ > + sshdr.asc == 0x20)) /* invalid command */ > /* this is no error here */ > return 0; > That seems to work equally well for me, thanks! Feel free to add when submitting: Reported-by: Sven Neumann <s.neumann@xxxxxxxxxxxx> Tested-by: Daniel Mack <zonque@xxxxxxxxx> Thanks for your help! Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
