mmc: Allow host drivers to specify max block count

Many controllers have an upper limit on the number of blocks that can be
transferred in one request. Allow the host drivers to specify this and make
sure we avoid hitting this limit.

Also change the max_sectors field to avoid confusion. This makes it map
less directly to the block layer limits, but as they didn't apply directly
on MMC cards anyway, this isn't a great loss.

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

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 9bda3fddad17..fb04bdd26c36 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -109,6 +109,9 @@ mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
         mrq->cmd->mrq = mrq;
         if (mrq->data) {
                 BUG_ON(mrq->data->blksz > host->max_blk_size);
+                BUG_ON(mrq->data->blocks > host->max_blk_count);
+                BUG_ON(mrq->data->blocks * mrq->data->blksz >
+                        host->max_req_size);
 
                 mrq->cmd->data = mrq->data;
                 mrq->data->error = 0;
@@ -1605,10 +1608,11 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
                  */
                 host->max_hw_segs = 1;
                 host->max_phys_segs = 1;
-                host->max_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
                 host->max_seg_size = PAGE_CACHE_SIZE;
 
+                host->max_req_size = PAGE_CACHE_SIZE;
                 host->max_blk_size = 512;
+                host->max_blk_count = PAGE_CACHE_SIZE / 512;
         }
 
         return host;