-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 11/20/2013 09:48 AM, Phillip Susi wrote: > My original idea was actually to just have the system resume force > the runtime pm status to suspended, then it will take care of > calling the runtime resume which can easily start the drive, but I > was hoping to get it working whether or not runtime pm is > configured. I may just have to fall back to that.
So the problem with this is that some drives spin up without being issued the START UNIT command. ATA disks without PuiS enabled do, and the SCSI standards indicate that scsi disks can be configured to do so as well, though the method for configuring that is not defined in the standard ( do such things actually exist? ). This would leave the drive spun up but the kernel thinking it is runtime suspended, which isn't good either. I think the way to deal with this is to throw a work queue item in the system resume method that issues TEST UNIT READY and if the drive indicates that it is currently active, then force the runtime pm status back to active. According to SAT-3, an ata emulation layer should issue CHECK POWER MODE and return POWER CONDITION CHANGE TO STANDBY, but libata does not do this; instead it always returns 0/0/0 for the sense status, so this would need fixed as well. Does this sound like the right idea? Also, I don't see any of the ASQ/ASCQ codes defined in the headers. Am I missing them or are they just not there? Also, I'm a bit unclear on whether you actually have to issue TEST UNIT READY or can just issue REQUEST SENSE to check the power condition. The standards seem to indicate the latter, but I'm not sure if REQUEST SENSE would return the sense status of the previous command rather than the power status, so you need the TEST UNIT READY first. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.14 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCgAGBQJSlp7ZAAoJEI5FoCIzSKrw5PIH/0wGsyAEr9xR6BkN/C7SOSNh ArhET3A+Af4Zo1HTe9vKDOIsf9OTrjXxWuLYDBoZSCC0GOw3XPYPdnZ1V4xIBtey 0lMSa8VU9KZMZs8KTYNp6LWToBqChBHSFEd9FLwdWnqLKCp/CtOqgeHO1wOyt1LJ NkYM4Mpsx6dGO7dzCTZ6Q5ogoXtGcokbGvUXbvuR1idNy1dEdBHaGStaVmIXxImd u2uJI+1ygk9lMvIa66zJK4f5X6OATd3+SkJlJTsAiEayOEqSAxXNh3QmYJzmJdy/ PDVdgjkgavpKDvbJjNBDSF9skbF9z40EK2NQ9R2kvUMHA8ui66/AQfQHAr04aZI= =kjuO -----END PGP SIGNATURE----- -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
