RE: [RFC PATCH v6 5/5] mmc: queue: Use bigger segments if IOMMU can merge the segments

[Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>]

Hi Wolfram-san,

> From: Wolfram Sang, Sent: Friday, June 14, 2019 4:59 AM
> 
> > -	blk_queue_max_segments(mq->queue, host->max_segs);
> > +	/* blk_queue_can_use_iommu_merging() should succeed if can_merge = 1 */
> > +	if (host->can_merge &&
> > +	    !blk_queue_can_use_iommu_merging(mq->queue, mmc_dev(host)))
> > +		WARN_ON(1);
> > +	blk_queue_max_segments(mq->queue, mmc_get_max_segments(host));
> 
> Maybe we could use WARN here to save the comment and move the info to
> the printout?
> 
> -	blk_queue_max_segments(mq->queue, host->max_segs);
> +	if (host->can_merge)
> +		WARN(!blk_queue_can_use_iommu_merging(mq->queue, mmc_dev(host)),
> +		     "merging was advertised but not possible\n");
> +	blk_queue_max_segments(mq->queue, mmc_get_max_segments(host));

Thank you for the suggestion. It's a good idea! I'll fix the patch.

Best regards,
Yoshihiro Shimoda