| Message ID | 20190411070948.29564-2-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] mmc: let the dma map ops handle bouncing | expand |
Hi Christoph, On Thu, 11 Apr 2019 at 09:10, Christoph Hellwig <hch@lst.de> wrote: > > Just like we do for all other block drivers. Especially as the limit > imposed at the moment might be way to pessimistic for iommus. I would appreciate some information in the changelog, as it's quite unclear of what this change really means. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > drivers/mmc/core/queue.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c > index 7c364a9c4eeb..eb9c0692062c 100644 > --- a/drivers/mmc/core/queue.c > +++ b/drivers/mmc/core/queue.c > @@ -354,18 +354,15 @@ static const struct blk_mq_ops mmc_mq_ops = { > static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card) > { > struct mmc_host *host = card->host; > - u64 limit = BLK_BOUNCE_HIGH; > unsigned block_size = 512; > > - if (mmc_dev(host)->dma_mask && *mmc_dev(host)->dma_mask) > - limit = (u64)dma_max_pfn(mmc_dev(host)) << PAGE_SHIFT; > - > blk_queue_flag_set(QUEUE_FLAG_NONROT, mq->queue); > blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, mq->queue); > if (mmc_can_erase(card)) > mmc_queue_setup_discard(mq->queue, card); > > - blk_queue_bounce_limit(mq->queue, limit); > + if (!mmc_dev(host)->dma_mask || !*mmc_dev(host)->dma_mask) > + blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_HIGH); So this means we are not going to set a bounce limit for the queue, in case we have a dma mask. Why isn't that needed no more? Whats has changed? > blk_queue_max_hw_sectors(mq->queue, > min(host->max_blk_count, host->max_req_size / 512)); > blk_queue_max_segments(mq->queue, host->max_segs); > -- > 2.20.1 > Kind regards Uffe
On Thu, Apr 11, 2019 at 11:00:56AM +0200, Ulf Hansson wrote: > > blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, mq->queue); > > if (mmc_can_erase(card)) > > mmc_queue_setup_discard(mq->queue, card); > > > > - blk_queue_bounce_limit(mq->queue, limit); > > + if (!mmc_dev(host)->dma_mask || !*mmc_dev(host)->dma_mask) > > + blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_HIGH); > > So this means we are not going to set a bounce limit for the queue, in > case we have a dma mask. > > Why isn't that needed no more? Whats has changed? On most architectures it was never needed, the major hold out was x86-32 with PAE. In general the dma_mask tells the DMA API layer what is supported, and if the physical addressing doesn't support that it has to use bounce buffering like swiotlb (or dmabounce on arm32). A couple month ago I finally fixes x86-32 to also properly set up swiotlb, and remove the block layerer bounce buffering that wasn't for highmem (which is about having a kernel mapping, not addressing), and ISA DMA (which is not handled like everything else, but we'll get there). But for some reason I missed mmc back then, so mmc right now is the only remaining user of address based block layer bouncing.
diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c index 7c364a9c4eeb..eb9c0692062c 100644 --- a/drivers/mmc/core/queue.c +++ b/drivers/mmc/core/queue.c @@ -354,18 +354,15 @@ static const struct blk_mq_ops mmc_mq_ops = { static void mmc_setup_queue(struct mmc_queue *mq, struct mmc_card *card) { struct mmc_host *host = card->host; - u64 limit = BLK_BOUNCE_HIGH; unsigned block_size = 512; - if (mmc_dev(host)->dma_mask && *mmc_dev(host)->dma_mask) - limit = (u64)dma_max_pfn(mmc_dev(host)) << PAGE_SHIFT; - blk_queue_flag_set(QUEUE_FLAG_NONROT, mq->queue); blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, mq->queue); if (mmc_can_erase(card)) mmc_queue_setup_discard(mq->queue, card); - blk_queue_bounce_limit(mq->queue, limit); + if (!mmc_dev(host)->dma_mask || !*mmc_dev(host)->dma_mask) + blk_queue_bounce_limit(mq->queue, BLK_BOUNCE_HIGH); blk_queue_max_hw_sectors(mq->queue, min(host->max_blk_count, host->max_req_size / 512)); blk_queue_max_segments(mq->queue, host->max_segs);
Just like we do for all other block drivers. Especially as the limit imposed at the moment might be way to pessimistic for iommus. Signed-off-by: Christoph Hellwig <hch@lst.de> --- drivers/mmc/core/queue.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)