Messages in this thread | | | Date | Wed, 11 Aug 2004 10:09:36 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH] SCSI midlayer power management |
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Hi!
> This proposed patch implements enough power-management support within > the SCSI midlayer to get ACPI S3 working on my system. Changes as follows: > > * Add generic_scsi_{suspend,resume} methods to scsi.c > * Add suspend and resume callbacks to the scsi_driver structure, and > implement those callbacks in sd.c > * In sd.c, we call sd_shutdown on suspend, in order to synchronize the > write-back cache. > * In sd.c, we call sd_rescan from sd_resume in order to ensure that > drives have spun up and avoid passing not ready errors back to the block > layer. > * In generic_scsi_suspend, we call scsi_device_quiesce before calling > the scsi_driver suspend callback. We resume from quiesce state in > reverse order in generic_scsi_resume. > > ACPI S1 and S4/swsusp are untested, but I think there should be no > regressions with S1. To do S1 properly, we probably need to tell the > drive to spin down, and I don't know what the SCSI command is for > that... For S4, the call to scsi_device_quiesce might pose a problem for > the subsequent state dump to disk. But I'm not sure swsusp ever worked > for SCSI.
swsusp will then resume disk and write the image, that should not be a problem. Is it guaranteed that after generic_scsi_suspend() no DMA is going on?
Anyway, you should try swsusp, preferably on some IDE notebook first and prefereably -mm one, to get feel how it works. It should be possible/easy to make it work with SCSI...
> This might help SATA drives, too, but I seem to remember that the SATA > layer doesn't properly emulate the SYNCHRONIZE_CACHE command. > > Comments, anybody? Can this be applied upstream? I think it's a step in > the right direction.
Looks good to me. Pavel -- People were complaining that M$ turns users into beta-testers... ...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl! - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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