mmc: bounce requests for simple hosts

Some hosts cannot do scatter/gather in hardware. Since not doing sg
is such a big performance hit, we (optionally) bounce the requests
to a simple linear buffer that we hand over to the driver.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/mmc/card/queue.h b/drivers/mmc/card/queue.h
index 1590b3f3f1f7..64e66e0d4994 100644
--- a/drivers/mmc/card/queue.h
+++ b/drivers/mmc/card/queue.h
@@ -14,6 +14,9 @@ struct mmc_queue {
         void                    *data;
         struct request_queue    *queue;
         struct scatterlist      *sg;
+        char                    *bounce_buf;
+        struct scatterlist      *bounce_sg;
+        unsigned int            bounce_sg_len;
 };
 
 extern int mmc_init_queue(struct mmc_queue *, struct mmc_card *, spinlock_t *);
@@ -21,4 +24,8 @@ extern void mmc_cleanup_queue(struct mmc_queue *);
 extern void mmc_queue_suspend(struct mmc_queue *);
 extern void mmc_queue_resume(struct mmc_queue *);
 
+extern unsigned int mmc_queue_map_sg(struct mmc_queue *);
+extern void mmc_queue_bounce_pre(struct mmc_queue *);
+extern void mmc_queue_bounce_post(struct mmc_queue *);
+
 #endif