On Fri, Feb 19, 2016 at 09:50:50AM +1100, Julian Calaby wrote: > Hi Mika, > > On Thu, Feb 18, 2016 at 7:54 PM, Mika Westerberg > <mika.westerberg@xxxxxxxxxxxxxxx> wrote: > > Runtime PM of the SCSI host is already handled by calls to > > scsi_autopm_get_host() and scsi_autopm_put_host() from appropriate places > > whenever the host needs to be powered on. This works fine when there is > > device connected to the host as once it runtime suspends the host will too. > > > > However, if there is no device connected the host is never runtime > > suspended (the usage counter is always 0). > > > > Allow runtime suspend of host even if it has no devices connected by > > calling scsi_autopm_put_host() at the end of scsi_add_host_with_dma(). We > > temporarily increase runtime PM usage counter first so call to > > scsi_autopm_put_host() will result idle request to be scheduled for the > > device. > > > > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > > --- > > drivers/scsi/hosts.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c > > index 82ac1cd818ac..e46bf4d152a0 100644 > > --- a/drivers/scsi/hosts.c > > +++ b/drivers/scsi/hosts.c > > @@ -250,6 +250,12 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev, > > if (error) > > goto out_destroy_freelist; > > > > + /* > > + * Increase usage count temporarily here so that calling > > + * scsi_autopm_put_host() will trigger runtime idle if there is > > + * nothing else preventing suspending the device. > > + */ > > + pm_runtime_get_noresume(&shost->shost_gendev); > > pm_runtime_set_active(&shost->shost_gendev); > > pm_runtime_enable(&shost->shost_gendev); > > device_enable_async_suspend(&shost->shost_gendev); > > @@ -290,6 +296,7 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev, > > goto out_destroy_host; > > > > scsi_proc_host_add(shost); > > + scsi_autopm_put_host(shost); > > Would it be cleaner to export the code that runs when the usage > counter decrements and call it here? There actually is no code to run. This just ensures that the device runtime_idle gets called which allows the parent device to runtime suspend (as it returns 0). Alternative way would be just to call pm_request_idle() directly here. -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
