lkml.org 
[lkml]   [2012]   [Mar]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [RFC PATCH v2 8/8] [SCSI] sr: check and enable Zero-power ODD support
    From
    Date
    On Fri, 2012-03-02 at 23:08 +0800, Aaron Lu wrote:
    > Hi,
    >
    > On Fri, Mar 2, 2012 at 3:02 PM, Lin Ming <ming.m.lin@intel.com> wrote:
    > > On Thu, 2012-03-01 at 11:02 -0500, Alan Stern wrote:
    > >> On Thu, 1 Mar 2012, Lin Ming wrote:
    > >>
    > >> > ZPODD(Zero Power Optical Disk Drive) is a new feature in
    > >> > SATA 3.1 specification. It provides a way to power off unused ODD.
    > >> >
    > >> > ZPODD support is checked in in sr_probe().
    > >> > can_power_off flag is set during suspend if ZPODD is supported.
    > >> >
    > >> > ATA port's runtime suspend callback will actually power off the ODD
    > >> > and its runtime resume callback will actually power on the ODD.
    > >> >
    > >> > When ODD is powered off(D3Cold state), inserting disk will trigger a
    > >> > wakeup event(GPE). GPE AML handler notifies the associated device. Then
    > >> > ODD is resumed in the notify handler.
    > >>
    > >> I have one stylistic comment on this patch...
    > >>
    > >> > diff --git a/drivers/scsi/sr.h b/drivers/scsi/sr.h
    > >> > index 37c8f6b..39b3d8c 100644
    > >> > --- a/drivers/scsi/sr.h
    > >> > +++ b/drivers/scsi/sr.h
    > >> > @@ -42,6 +42,9 @@ typedef struct scsi_cd {
    > >> > unsigned readcd_cdda:1; /* reading audio data using READ_CD */
    > >> > unsigned media_present:1; /* media is present */
    > >> >
    > >> > + unsigned zpodd:1; /* is ZPODD supported */
    > >> > + unsigned zpodd_event:1;
    > >> > +
    > >>
    > >> You should not expect your readers to understand what "ZPODD" means.
    > >> drivers/scsi/sr.h is used by lots of different people, many of whom
    > >> will have no idea what it refers to, especially since it is part of
    > >> the SATA spec and not the SCSI spec. You should provide a brief
    > >> explanation.
    > >
    > > I'll add some explanation.
    > >
    > > But I'm thinking maybe it's better to move this flag to ata layer, for
    >
    > Agree.
    >
    > > example, adding a flag to libata.h
    > >
    > > ATA_DFLAG_ZPODD
    > >
    >
    > How about ATA_DFLAG_DA(device attention)?

    Yes, it's better.

    > It follows the name used in the sata spec and this feature might have
    > other uses in the future in addition to zero power odd(just my wild guess).
    >
    > > sr runtime pm is only enabled when ZPODD(or more general, power off) is
    > > supported.
    > > So the problem is how will sr driver know this flag?
    > >
    >
    > What about adding a new field to scsi_device to reflect this capability of
    > the underlying sata device? We can then set this field in ata_scsi_scan_host.

    Nice idea.

    I'll refresh this patch.

    Thanks,
    Lin Ming



    \
     
     \ /
      Last update: 2012-03-03 04:09    [W:0.026 / U:59.992 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site