Hi Christoph,
> From: Christoph Hellwig, Sent: Monday, June 17, 2019 3:54 PM
>
> On Mon, Jun 17, 2019 at 06:46:33AM +0000, Yoshihiro Shimoda wrote:
> > > can_merge seems a little too generic a name to me. Maybe can_iommu_merge?
> >
> > I'll fix the name. Also, only the device_iommu_mapped() condition wiil cause
> > a problem on iommu=pt [1]. So, I'll add another condition here.
>
> Instead of adding another condition here I think we need to properly
> abstract it out in the DMA layer. E.g. have a
Thank you for your comment and sample code! I'll add such functions
on next patch series.
Best regards,
Yoshihiro Shimoda
> unsigned long dma_get_merge_boundary(struct device *dev)
> {
> const struct dma_map_ops *ops = get_dma_ops(dev);
>
> if (!ops || !ops->get_merge_boundary)
> return 0; /* can't merge */
> return ops->get_merge_boundary(dev);
> }
>
> and then implement the method in dma-iommu.c.
>
> blk_queue_can_use_iommu_merging then comes:
>
> bool blk_queue_enable_iommu_merging(struct request_queue *q,
> struct device *dev)
> {
> unsigned long boundary = dma_get_merge_boundary(dev);
>
> if (!boundary)
> return false;
> blk_queue_virt_boundary(q, boundary);
> return true;
> }
