On 2020-06-23 04:10, Martin Kepplinger wrote: > This add a very conservative but simple implementation for runtime PM > to the sd scsi driver: > Resume when opened (mounted) and suspend when released (unmounted). > > Improvements that allow suspending while a device is "open" can > be added later, but now we save power when no filesystem is mounted > and runtime PM is enabled. > > Signed-off-by: Martin Kepplinger <[email protected]> > --- > drivers/scsi/sd.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c > index d90fefffe31b..fe4cb7c50ec1 100644 > --- a/drivers/scsi/sd.c > +++ b/drivers/scsi/sd.c > @@ -1372,6 +1372,7 @@ static int sd_open(struct block_device *bdev, fmode_t > mode) > SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_open\n")); > > sdev = sdkp->device; > + scsi_autopm_get_device(sdev); > > /* > * If the device is in error recovery, wait until it is done. > @@ -1418,6 +1419,9 @@ static int sd_open(struct block_device *bdev, fmode_t > mode) > > error_out: > scsi_disk_put(sdkp); > + > + scsi_autopm_put_device(sdev); > + > return retval; > } > > @@ -1441,6 +1445,8 @@ static void sd_release(struct gendisk *disk, fmode_t > mode) > > SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp, "sd_release\n")); > > + scsi_autopm_put_device(sdev); > + > if (atomic_dec_return(&sdkp->openers) == 0 && sdev->removable) { > if (scsi_block_when_processing_errors(sdev)) > scsi_set_medium_removal(sdev, SCSI_REMOVAL_ALLOW);
My understanding of the above patch is that it introduces a regression, namely by disabling runtime suspend as long as an sd device is held open. Bart.
