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>

diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index 6413afa318d2c65532bd11dc6f36a539c6291107..defc11b4572c4264d6ca86a0f12e8341bb5dbec4 100644 (file)
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -101,6 +101,27 @@ static void mmc_request(struct request_queue *q)
                wake_up_process(mq->thread);
 }
 
+static void mmc_queue_setup_discard(struct request_queue *q,
+                                   struct mmc_card *card)
+{
+       unsigned max_discard;
+
+       max_discard = mmc_calc_max_discard(card);
+       if (!max_discard)
+               return;
+
+       queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
+       q->limits.max_discard_sectors = max_discard;
+       if (card->erased_byte == 0)
+               q->limits.discard_zeroes_data = 1;
+       q->limits.discard_granularity = card->pref_erase << 9;
+       /* granularity must not be greater than max. discard */
+       if (card->pref_erase > max_discard)
+               q->limits.discard_granularity = 0;
+       if (mmc_can_secure_erase_trim(card))
+               queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, q);
+}
+
 /**
  * mmc_init_queue - initialise a queue structure.
  * @mq: mmc queue
@@ -130,16 +151,8 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card,
 
        blk_queue_prep_rq(mq->queue, mmc_prep_request);
        queue_flag_set_unlocked(QUEUE_FLAG_NONROT, mq->queue);
-       if (mmc_can_erase(card)) {
-               queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mq->queue);
-               mq->queue->limits.max_discard_sectors = UINT_MAX;
-               if (card->erased_byte == 0)
-                       mq->queue->limits.discard_zeroes_data = 1;
-               mq->queue->limits.discard_granularity = card->pref_erase << 9;
-               if (mmc_can_secure_erase_trim(card))
-                       queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD,
-                                               mq->queue);
-       }
+       if (mmc_can_erase(card))
+               mmc_queue_setup_discard(mq->queue, card);
 
 #ifdef CONFIG_MMC_BLOCK_BOUNCE
        if (host->max_segs == 1) {

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 7843efe22359916e82bb9781d74826ad457829f6..ac82865b8c2fc702aeeec88e4b18a2574b56cc02 100644 (file)
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1516,6 +1516,82 @@ int mmc_erase_group_aligned(struct mmc_card *card, unsigned int from,
 }
 EXPORT_SYMBOL(mmc_erase_group_aligned);
 
+static unsigned int mmc_do_calc_max_discard(struct mmc_card *card,
+                                           unsigned int arg)
+{
+       struct mmc_host *host = card->host;
+       unsigned int max_discard, x, y, qty = 0, max_qty, timeout;
+       unsigned int last_timeout = 0;
+
+       if (card->erase_shift)
+               max_qty = UINT_MAX >> card->erase_shift;
+       else if (mmc_card_sd(card))
+               max_qty = UINT_MAX;
+       else
+               max_qty = UINT_MAX / card->erase_size;
+
+       /* Find the largest qty with an OK timeout */
+       do {
+               y = 0;
+               for (x = 1; x && x <= max_qty && max_qty - x >= qty; x <<= 1) {
+                       timeout = mmc_erase_timeout(card, arg, qty + x);
+                       if (timeout > host->max_discard_to)
+                               break;
+                       if (timeout < last_timeout)
+                               break;
+                       last_timeout = timeout;
+                       y = x;
+               }
+               qty += y;
+       } while (y);
+
+       if (!qty)
+               return 0;
+
+       if (qty == 1)
+               return 1;
+
+       /* Convert qty to sectors */
+       if (card->erase_shift)
+               max_discard = --qty << card->erase_shift;
+       else if (mmc_card_sd(card))
+               max_discard = qty;
+       else
+               max_discard = --qty * card->erase_size;
+
+       return max_discard;
+}
+
+unsigned int mmc_calc_max_discard(struct mmc_card *card)
+{
+       struct mmc_host *host = card->host;
+       unsigned int max_discard, max_trim;
+
+       if (!host->max_discard_to)
+               return UINT_MAX;
+
+       /*
+        * Without erase_group_def set, MMC erase timeout depends on clock
+        * frequence which can change.  In that case, the best choice is
+        * just the preferred erase size.
+        */
+       if (mmc_card_mmc(card) && !(card->ext_csd.erase_group_def & 1))
+               return card->pref_erase;
+
+       max_discard = mmc_do_calc_max_discard(card, MMC_ERASE_ARG);
+       if (mmc_can_trim(card)) {
+               max_trim = mmc_do_calc_max_discard(card, MMC_TRIM_ARG);
+               if (max_trim < max_discard)
+                       max_discard = max_trim;
+       } else if (max_discard < card->erase_size) {
+               max_discard = 0;
+       }
+       pr_debug("%s: calculated max. discard sectors %u for timeout %u ms\n",
+                mmc_hostname(host), max_discard, host->max_discard_to);
+       return max_discard;
+}
+EXPORT_SYMBOL(mmc_calc_max_discard);
+
 int mmc_set_blocklen(struct mmc_card *card, unsigned int blocklen)
 {
        struct mmc_command cmd = {0};

diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index 791f060a6f1db8610817ce297c448db47006255b..86d81cf75b70ad1e2081b8550cfc16acdcf3d212 100644 (file)
--- 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 fc24b38b48cbec13107a92342efa277839867d0a..c67d19b5542ac9564e86ba7e44163f4e8548f410 100644 (file)
--- 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 */