mmc: remove multiwrite capability

Relax requirements on host controllers and only require that they do not
report a transfer count than is larger than the actual one (i.e. a lower
value is okay). This is how many other parts of the kernel behaves so
upper layers should already be prepared to handle that scenario. This
gives us a performance boost on MMC cards.

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

9 files changed, 30 insertions, 44 deletions

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 4b0f8220f153..66e5a5487c20 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -237,17 +237,6 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
                 if (brq.data.blocks > card->host->max_blk_count)
                         brq.data.blocks = card->host->max_blk_count;
 
-                /*
-                 * If the host doesn't support multiple block writes, force
-                 * block writes to single block. SD cards are excepted from
-                 * this rule as they support querying the number of
-                 * successfully written sectors.
-                 */
-                if (rq_data_dir(req) != READ &&
-                    !(card->host->caps & MMC_CAP_MULTIWRITE) &&
-                    !mmc_card_sd(card))
-                        brq.data.blocks = 1;
-
                 if (brq.data.blocks > 1) {
                         /* SPI multiblock writes terminate using a special
                          * token, not a STOP_TRANSMISSION request.
@@ -367,30 +356,32 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
          * mark the known good sectors as ok.
          *
          * If the card is not SD, we can still ok written sectors
-         * if the controller can do proper error reporting.
+         * as reported by the controller (which might be less than
+         * the real number of written sectors, but never more).
          *
          * For reads we just fail the entire chunk as that should
          * be safe in all cases.
          */
-        if (rq_data_dir(req) != READ && mmc_card_sd(card)) {
-                u32 blocks;
-                unsigned int bytes;
-
-                blocks = mmc_sd_num_wr_blocks(card);
-                if (blocks != (u32)-1) {
-                        if (card->csd.write_partial)
-                                bytes = blocks << md->block_bits;
-                        else
-                                bytes = blocks << 9;
+        if (rq_data_dir(req) != READ) {
+                if (mmc_card_sd(card)) {
+                        u32 blocks;
+                        unsigned int bytes;
+
+                        blocks = mmc_sd_num_wr_blocks(card);
+                        if (blocks != (u32)-1) {
+                                if (card->csd.write_partial)
+                                        bytes = blocks << md->block_bits;
+                                else
+                                        bytes = blocks << 9;
+                                spin_lock_irq(&md->lock);
+                                ret = __blk_end_request(req, 0, bytes);
+                                spin_unlock_irq(&md->lock);
+                        }
+                } else {
                         spin_lock_irq(&md->lock);
-                        ret = __blk_end_request(req, 0, bytes);
+                        ret = __blk_end_request(req, 0, brq.data.bytes_xfered);
                         spin_unlock_irq(&md->lock);
                 }
-        } else if (rq_data_dir(req) != READ &&
-                   (card->host->caps & MMC_CAP_MULTIWRITE)) {
-                spin_lock_irq(&md->lock);
-                ret = __blk_end_request(req, 0, brq.data.bytes_xfered);
-                spin_unlock_irq(&md->lock);
         }
 
         mmc_release_host(card->host);
diff --git a/drivers/mmc/host/at91_mci.c b/drivers/mmc/host/at91_mci.c
index 16df235fcc2e..f15e2064305c 100644
--- a/drivers/mmc/host/at91_mci.c
+++ b/drivers/mmc/host/at91_mci.c
@@ -995,7 +995,7 @@ static int __init at91_mci_probe(struct platform_device *pdev)
         mmc->f_min = 375000;
         mmc->f_max = 25000000;
         mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
-        mmc->caps = MMC_CAP_MULTIWRITE | MMC_CAP_SDIO_IRQ;
+        mmc->caps = MMC_CAP_SDIO_IRQ;
 
         mmc->max_blk_size = 4095;
         mmc->max_blk_count = mmc->max_req_size;
diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index 25d5324ab7e2..cce873c5a149 100644
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -849,7 +849,7 @@ static int __init atmci_probe(struct platform_device *pdev)
         mmc->f_min = (host->bus_hz + 511) / 512;
         mmc->f_max = host->bus_hz / 2;
         mmc->ocr_avail  = MMC_VDD_32_33 | MMC_VDD_33_34;
-        mmc->caps |= MMC_CAP_4_BIT_DATA | MMC_CAP_MULTIWRITE;
+        mmc->caps |= MMC_CAP_4_BIT_DATA;
 
         mmc->max_hw_segs = 64;
         mmc->max_phys_segs = 64;
diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c
index 4e82f64a96bc..41cc63360e43 100644
--- a/drivers/mmc/host/mmc_spi.c
+++ b/drivers/mmc/host/mmc_spi.c
@@ -1252,10 +1252,7 @@ static int mmc_spi_probe(struct spi_device *spi)
         mmc->ops = &mmc_spi_ops;
         mmc->max_blk_size = MMC_SPI_BLOCKSIZE;
 
-        /* As long as we keep track of the number of successfully
-         * transmitted blocks, we're good for multiwrite.
-         */
-        mmc->caps = MMC_CAP_SPI | MMC_CAP_MULTIWRITE;
+        mmc->caps = MMC_CAP_SPI;
 
         /* SPI doesn't need the lowspeed device identification thing for
          * MMC or SD cards, since it never comes up in open drain mode.
diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index da5fecad74d9..696cf3647ceb 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -535,7 +535,6 @@ static int mmci_probe(struct amba_device *dev, void *id)
         mmc->f_min = (host->mclk + 511) / 512;
         mmc->f_max = min(host->mclk, fmax);
         mmc->ocr_avail = plat->ocr_mask;
-        mmc->caps = MMC_CAP_MULTIWRITE;
 
         /*
          * We can do SGIO
diff --git a/drivers/mmc/host/omap.c b/drivers/mmc/host/omap.c
index 549517c35675..dbc26eb6a89e 100644
--- a/drivers/mmc/host/omap.c
+++ b/drivers/mmc/host/omap.c
@@ -1317,7 +1317,7 @@ static int __init mmc_omap_new_slot(struct mmc_omap_host *host, int id)
 
         host->slots[id] = slot;
 
-        mmc->caps = MMC_CAP_MULTIWRITE;
+        mmc->caps = 0;
         if (host->pdata->conf.wire4)
                 mmc->caps |= MMC_CAP_4_BIT_DATA;
 
diff --git a/drivers/mmc/host/tifm_sd.c b/drivers/mmc/host/tifm_sd.c
index 1c14a186f000..13844843e8de 100644
--- a/drivers/mmc/host/tifm_sd.c
+++ b/drivers/mmc/host/tifm_sd.c
@@ -973,7 +973,7 @@ static int tifm_sd_probe(struct tifm_dev *sock)
 
         mmc->ops = &tifm_sd_ops;
         mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
-        mmc->caps = MMC_CAP_4_BIT_DATA | MMC_CAP_MULTIWRITE;
+        mmc->caps = MMC_CAP_4_BIT_DATA;
         mmc->f_min = 20000000 / 60;
         mmc->f_max = 24000000;
 
diff --git a/drivers/mmc/host/wbsd.c b/drivers/mmc/host/wbsd.c
index f7dcd8ec0d7f..adda37952032 100644
--- a/drivers/mmc/host/wbsd.c
+++ b/drivers/mmc/host/wbsd.c
@@ -1219,7 +1219,7 @@ static int __devinit wbsd_alloc_mmc(struct device *dev)
         mmc->f_min = 375000;
         mmc->f_max = 24000000;
         mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
-        mmc->caps = MMC_CAP_4_BIT_DATA | MMC_CAP_MULTIWRITE;
+        mmc->caps = MMC_CAP_4_BIT_DATA;
 
         spin_lock_init(&host->lock);
 
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 753b7231b887..10a2080086ca 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -111,12 +111,11 @@ struct mmc_host {
         unsigned long           caps;           /* Host capabilities */
 
 #define MMC_CAP_4_BIT_DATA      (1 << 0)        /* Can the host do 4 bit transfers */
-#define MMC_CAP_MULTIWRITE      (1 << 1)        /* Can accurately report bytes sent to card on error */
-#define MMC_CAP_MMC_HIGHSPEED   (1 << 2)        /* Can do MMC high-speed timing */
-#define MMC_CAP_SD_HIGHSPEED    (1 << 3)        /* Can do SD high-speed timing */
-#define MMC_CAP_SDIO_IRQ        (1 << 4)        /* Can signal pending SDIO IRQs */
-#define MMC_CAP_SPI             (1 << 5)        /* Talks only SPI protocols */
-#define MMC_CAP_NEEDS_POLL      (1 << 6)        /* Needs polling for card-detection */
+#define MMC_CAP_MMC_HIGHSPEED   (1 << 1)        /* Can do MMC high-speed timing */
+#define MMC_CAP_SD_HIGHSPEED    (1 << 2)        /* Can do SD high-speed timing */
+#define MMC_CAP_SDIO_IRQ        (1 << 3)        /* Can signal pending SDIO IRQs */
+#define MMC_CAP_SPI             (1 << 4)        /* Talks only SPI protocols */
+#define MMC_CAP_NEEDS_POLL      (1 << 5)        /* Needs polling for card-detection */
 
         /* host specific block data */
         unsigned int            max_seg_size;   /* see blk_queue_max_segment_size */