mmc: queue: let host controllers specify maximum discard timeout

Some host controllers will not operate without a hardware
timeout that is limited in value.  However large discards
require large timeouts, so there needs to be a way to
specify the maximum discard size.

A host controller driver may now specify the maximum discard
timeout possible so that max_discard_sectors can be calculated.

However, for eMMC when the High Capacity Erase Group Size
is not in use, the timeout calculation depends on clock
rate which may change.  For that case Preferred Erase Size
is used instead.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

2 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index 791f060a6f1d..86d81cf75b70 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -155,6 +155,7 @@ extern int mmc_can_trim(struct mmc_card *card);
 extern int mmc_can_secure_erase_trim(struct mmc_card *card);
 extern int mmc_erase_group_aligned(struct mmc_card *card, unsigned int from,
                                    unsigned int nr);
+extern unsigned int mmc_calc_max_discard(struct mmc_card *card);
 
 extern int mmc_set_blocklen(struct mmc_card *card, unsigned int blocklen);
 
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index fc24b38b48cb..c67d19b5542a 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -231,6 +231,7 @@ struct mmc_host {
         unsigned int            max_req_size;   /* maximum number of bytes in one req */
         unsigned int            max_blk_size;   /* maximum size of one mmc block */
         unsigned int            max_blk_count;  /* maximum number of blocks in one req */
+        unsigned int            max_discard_to; /* max. discard timeout in ms */
 
         /* private data */
         spinlock_t              lock;           /* lock for claim and bus ops */