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 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 cebe5e00 3629319750 S Bo:1:003:2 -115 31 = 55534243 12000000 00000000 00000a35 00000000 00000000 00000000 000000 cebe5e00 3629319826 C Bo:1:003:2 0 31 > cebe5e00 3629319856 S Bi:1:003:1 -115 13 < cebe5e00 3629319910 C Bi:1:003:1 0 13 = 55534253 12000000 00000000 01 cebe5e00 3629319964 S Bo:1:003:2 -115 31 = 55534243 13000000 12000000 80000603 00000012 00000000 00000000 000000 cebe5e00 3629319996 C Bo:1:003:2 0 31 > cecd4300 3629320026 S Bi:1:003:1 -115 18 < cecd4300 3629320086 C Bi:1:003:1 0 18 = 70000500 0000000a 00000000 20000000 0000 cebe5e00 3629320111 S Bi:1:003:1 -115 13 < cebe5e00 3629320152 C Bi:1:003:1 0 13 = 55534253 13000000 00000000 00 cebe5e00 3629320360 S Bo:1:003:2 -115 31 = 55534243 14000000 00000000 00000a35 00000000 00000000 00000000 000000 cebe5e00 3629320610 C Bo:1:003:2 0 31 > cebe5e00 3629320670 S Bi:1:003:1 -115 13 < cebe5e00 3629320714 C Bi:1:003:1 0 13 = 55534253 14000000 00000000 01 cebe5e00 3629320752 S Bo:1:003:2 -115 31 = 55534243 15000000 12000000 80000603 00000012 00000000 00000000 000000 cebe5e00 3629320809 C Bo:1:003:2 0 31 > cecd4300 3629320834 S Bi:1:003:1 -115 18 < cecd4300 3629320863 C Bi:1:003:1 0 18 = 70000500 0000000a 00000000 20000000 0000 cebe5e00 3629320885 S Bi:1:003:1 -115 13 < cebe5e00 3629320923 C Bi:1:003:1 0 13 = 55534253 15000000 00000000 00 ceb36280 3629350243 C Ii:1:001:1 -2:2048 0 cecd4800 3630011191 S Ci:1:001:0 s a3 00 0000 0001 0004 4 < cecd4800 3630011333 C Ci:1:001:0 0 4 = 07051200 cecd4800 3630011574 S Co:1:001:0 s 23 01 0011 0001 0000 0 cecd4800 3630011699 C Co:1:001:0 0 0 cecd4800 3630011745 S Co:1:001:0 s 23 01 0014 0001 0000 0 cecd4800 3630011789 C Co:1:001:0 0 0 ceb36280 3630112579 S Ii:1:001:1 -115:2048 4 < cecd4500 3630112825 S Ci:1:001:0 s a3 00 0000 0001 0004 4 < cecd4500 3630112952 C Ci:1:001:0 0 4 = 07050000 cecd4500 3630113001 S Co:1:001:0 s 23 01 0002 0001 0000 0 cecd4500 3630113084 C Co:1:001:0 0 0 ceb36280 3630122552 C Ii:1:001:1 0:2048 1 = 02 ceb36280 3630122566 S Ii:1:001:1 -115:2048 4 < cecd4500 3630152573 S Ci:1:001:0 s a3 00 0000 0001 0004 4 < cecd4500 3630152625 C Ci:1:001:0 0 4 = 03050000 cecd4500 3630172588 S Ci:1:003:0 s 80 00 0000 0000 0002 2 < cecd4500 3630172603 E Ci:1:003:0 -19 0 cecd4500 3630172744 S Co:1:001:0 s 23 03 0004 0001 0000 0 cecd4500 3630184219 C Co:1:001:0 0 0 cecd4500 3630242590 S Ci:1:001:0 s a3 00 0000 0001 0004 4 < cecd4500 3630242657 C Ci:1:001:0 0 4 = 13050000 cecd4500 3630302564 S Ci:1:001:0 s a3 00 0000 0001 0004 4 < cecd4500 3630302609 C Ci:1:001:0 0 4 = 13050000 ceb36280 3630315035 C Ii:1:001:1 0:2048 1 = 02 FWIW, the following patch seems to work fine on our machines, but as I said, I'm uncertain wrt to whether that's the right approach. diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 69725f7..ec99787 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -1469,6 +1469,7 @@ static int sd_sync_cache(struct scsi_disk *sdkp) return 0; switch (host_byte(res)) { + case DID_OK: /* ignore errors due to racing a disconnection */ case DID_BAD_TARGET: case DID_NO_CONNECT: Thanks, Daniel -- 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