Re: [PATCH RFC v1 1/1] scsi: pm: Leave runtime resume along if block layer PM is enabled

[Bart Van Assche <bvanassche@acm.org>]

On 11/12/20 10:30 PM, Can Guo wrote:
> If block layer runtime PM is enabled for one SCSI device, then there is
> no need to forcibly change the SCSI device and its request queue's runtime
> PM status to active in scsi_dev_type_resume(), since block layer PM shall
> resume the SCSI device on the demand of bios.

Please change "along" into "alone" in the subject of this patch (if that
is what you meant).

> +	if (scsi_is_sdev_device(dev)) {
> +		struct scsi_device *sdev;
>  
> +		sdev = to_scsi_device(dev);

A minor comment: I think that "struct scsi_device *sdev =
to_scsi_device(dev);" fits on a single line.

> +		 * If block layer runtime PM is enabled for the SCSI device,
> +		 * let block layer PM handle its runtime PM routines.

Please change "its runtime PM routines" into "runtime resume" or
similar. I think that will make the comment more clear.

> +		if (sdev->request_queue->dev)
> +			return err;
> +	}

The 'dev' member only exists in struct request_queue if CONFIG_PM=y so
the above won't compile if CONFIG_PM=n. How about adding a function in
include/linux/blk-pm.h to check whether or not runtime PM has been enabled?

Otherwise this patch looks good to me.

Thanks,

Bart.