Adds support for writing multiple sectors at once. This allows
back-to-back transfers of sectors giving roughly double write throughput.
To be able to detect which sector is causing problems the system falls
back to single sector writes if a failure is detected.
Tested by several people with no side-effects found.
Signed-off-by: Pierre Ossman <[email protected]>
---
Previously submitted: 2005-03-16
Previously submitted: 2004-12-03
Index: linux-wbsd/drivers/mmc/mmc_block.c
===================================================================
--- linux-wbsd/drivers/mmc/mmc_block.c (revision 77)
+++ linux-wbsd/drivers/mmc/mmc_block.c (working copy)
@@ -166,9 +166,25 @@
struct mmc_blk_data *md = mq->data;
struct mmc_card *card = md->queue.card;
int ret;
+
+#ifdef CONFIG_MMC_BULKTRANSFER
+ int failsafe;
+#endif
if (mmc_card_claim_host(card))
goto cmd_err;
+
+#ifdef CONFIG_MMC_BULKTRANSFER
+ /*
+ * We first try transfering multiple blocks. If this fails
+ * we fall back to single block transfers.
+ *
+ * This gives us good performance when all is well and the
+ * possibility to determine which sector fails when all
+ * is not well.
+ */
+ failsafe = 0;
+#endif
do {
struct mmc_blk_request brq;
@@ -189,14 +205,32 @@
brq.stop.arg = 0;
brq.stop.flags = MMC_RSP_R1B;
+#ifdef CONFIG_MMC_BULKTRANSFER
+ /*
+ * A multi-block transfer failed. Falling back to single
+ * blocks.
+ */
+ if (failsafe)
+ brq.data.blocks = 1;
+
+#else
+ /*
+ * Writes are done one sector at a time.
+ */
+ if (rq_data_dir(req) != READ)
+ brq.data.blocks = 1;
+#endif
+
+ ret = 1;
+
if (rq_data_dir(req) == READ) {
brq.cmd.opcode = brq.data.blocks > 1 ? MMC_READ_MULTIPLE_BLOCK : MMC_READ_SINGLE_BLOCK;
brq.data.flags |= MMC_DATA_READ;
} else {
- brq.cmd.opcode = MMC_WRITE_BLOCK;
+ brq.cmd.opcode = brq.data.blocks > 1 ? MMC_WRITE_MULTIPLE_BLOCK :
+ MMC_WRITE_BLOCK;
brq.cmd.flags = MMC_RSP_R1B;
brq.data.flags |= MMC_DATA_WRITE;
- brq.data.blocks = 1;
}
brq.mrq.stop = brq.data.blocks > 1 ? &brq.stop : NULL;
@@ -204,19 +238,19 @@
if (brq.cmd.error) {
printk(KERN_ERR "%s: error %d sending read/write command\n",
req->rq_disk->disk_name, brq.cmd.error);
- goto cmd_err;
+ goto cmd_fail;
}
if (brq.data.error) {
printk(KERN_ERR "%s: error %d transferring data\n",
req->rq_disk->disk_name, brq.data.error);
- goto cmd_err;
+ goto cmd_fail;
}
if (brq.stop.error) {
printk(KERN_ERR "%s: error %d sending stop command\n",
req->rq_disk->disk_name, brq.stop.error);
- goto cmd_err;
+ goto cmd_fail;
}
do {
@@ -229,7 +263,7 @@
if (err) {
printk(KERN_ERR "%s: error %d requesting status\n",
req->rq_disk->disk_name, err);
- goto cmd_err;
+ goto cmd_fail;
}
} while (!(cmd.resp[0] & R1_READY_FOR_DATA));
@@ -255,6 +289,27 @@
end_that_request_last(req);
}
spin_unlock_irq(&md->lock);
+
+#ifdef CONFIG_MMC_BULKTRANSFER
+ /*
+ * Go back to bulk mode if in failsafe mode.
+ */
+ failsafe = 0;
+#endif
+
+ continue;
+
+ cmd_fail:
+
+#ifdef CONFIG_MMC_BULKTRANSFER
+ if (failsafe)
+ goto cmd_err;
+ else
+ failsafe = 1;
+#else
+ goto cmd_err;
+#endif
+
} while (ret);
mmc_card_release_host(card);
Index: linux-wbsd/drivers/mmc/Kconfig
===================================================================
--- linux-wbsd/drivers/mmc/Kconfig (revision 96)
+++ linux-wbsd/drivers/mmc/Kconfig (working copy)
@@ -41,6 +41,15 @@
mount the filesystem. Almost everyone wishing MMC support
should say Y or M here.
+config MMC_BULKTRANSFER
+ bool "Multi-block writes (EXPERIMENTAL)"
+ depends on MMC_BLOCK != n && EXPERIMENTAL
+ default n
+ help
+ By default all writes are done one sector at a time. Enable
+ this option to transfer as large blocks as the host supports.
+ The transfer speed is in most cases doubled.
+
config MMC_ARMMMCI
tristate "ARM AMBA Multimedia Card Interface support"
depends on ARM_AMBA && MMC
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