On Mon, 24 Jun 2019 at 08:24, Christoph Hellwig <hch@xxxxxx> wrote:
>
> On Thu, Jun 20, 2019 at 05:50:10PM +0900, Yoshihiro Shimoda wrote:
> > When the max_segs of a mmc host is smaller than 512, the mmc
> > subsystem tries to use 512 segments if DMA MAP layer can merge
> > the segments, and then the mmc subsystem exposes such information
> > to the block layer by using blk_queue_can_use_dma_map_merging().
> >
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
> > ---
> > drivers/mmc/core/queue.c | 35 ++++++++++++++++++++++++++++++++---
> > include/linux/mmc/host.h | 1 +
> > 2 files changed, 33 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
> > index 92900a0..ab0ecc6 100644
> > --- a/drivers/mmc/core/queue.c
> > +++ b/drivers/mmc/core/queue.c
> > @@ -24,6 +24,8 @@
> > #include "card.h"
> > #include "host.h"
> >
> > +#define MMC_DMA_MAP_MERGE_SEGMENTS 512
> > +
> > static inline bool mmc_cqe_dcmd_busy(struct mmc_queue *mq)
> > {
> > /* Allow only 1 DCMD at a time */
> > @@ -196,6 +198,12 @@ static void mmc_queue_setup_discard(struct request_queue *q,
> > blk_queue_flag_set(QUEUE_FLAG_SECERASE, q);
> > }
> >
> > +static unsigned int mmc_get_max_segments(struct mmc_host *host)
> > +{
> > + return host->can_dma_map_merge ? MMC_DMA_MAP_MERGE_SEGMENTS :
> > + host->max_segs;
>
> I personally don't like superflous use of ? : if an if would be more
> obvious:
>
> if (host->can_dma_map_merge)
> return MMC_DMA_MAP_MERGE_SEGMENTS;
> return host->max_segs;
>
> but that is really just a nitpick and for the mmc maintainer to decide.
I have no strong opinions, both formats are used in mmc code, so I am
fine as is.
>
> Otherwise looks good:
>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Kind regards
Uffe
