[U-Boot] [PATCH V3] mmc: seperate block number into small parts for multi-write cmd

[Lei Wen]

Constraint the mmc framework to only send no more than 65535
blocks in one go during the multi-write command. This constraint
comes due to the limitation of 16bit width block counter register
at some hardware.

Signed-off-by: Lei Wen <lei...@marvell.com>
Cc: Reinhard Meyer <u-b...@emk-elektronik.de>
---
V3: return to the V1 solution that keep the 65535 constraint,
    but cut the 512KiB dma limitation
V2: add additional members in mmc structure

 drivers/mmc/mmc.c |   52 ++++++++++++++++++++++++++++++++++++----------------
 1 files changed, 36 insertions(+), 16 deletions(-)

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 80cd9bf..18980e6 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -78,17 +78,11 @@ struct mmc *find_mmc_device(int dev_num)
 }
 
 static ulong
-mmc_bwrite(int dev_num, ulong start, lbaint_t blkcnt, const void*src)
+mmc_write_blocks(struct mmc *mmc, ulong start, lbaint_t blkcnt, const void*src)
 {
        struct mmc_cmd cmd;
        struct mmc_data data;
-       int err;
-       int stoperr = 0;
-       struct mmc *mmc = find_mmc_device(dev_num);
-       int blklen;
-
-       if (!mmc)
-               return -1;
+       int blklen, err;
 
        blklen = mmc->write_bl_len;
 
@@ -97,12 +91,6 @@ mmc_bwrite(int dev_num, ulong start, lbaint_t blkcnt, const 
void*src)
                        start + blkcnt, mmc->block_dev.lba);
                return 0;
        }
-       err = mmc_set_blocklen(mmc, mmc->write_bl_len);
-
-       if (err) {
-               printf("set write bl len failed\n\r");
-               return err;
-       }
 
        if (blkcnt > 1)
                cmd.cmdidx = MMC_CMD_WRITE_MULTIPLE_BLOCK;
@@ -123,7 +111,6 @@ mmc_bwrite(int dev_num, ulong start, lbaint_t blkcnt, const 
void*src)
        data.flags = MMC_DATA_WRITE;
 
        err = mmc_send_cmd(mmc, &cmd, &data);
-
        if (err) {
                printf("mmc write failed\n\r");
                return err;
@@ -134,9 +121,42 @@ mmc_bwrite(int dev_num, ulong start, lbaint_t blkcnt, 
const void*src)
                cmd.cmdarg = 0;
                cmd.resp_type = MMC_RSP_R1b;
                cmd.flags = 0;
-               stoperr = mmc_send_cmd(mmc, &cmd, NULL);
+               err = mmc_send_cmd(mmc, &cmd, NULL);
+               if (err) {
+                       printf("mmc fail to send stop cmd\n\r");
+                       return err;
+               }
+       }
+
+       return blkcnt;
+}
+
+static ulong
+mmc_bwrite(int dev_num, ulong start, lbaint_t blkcnt, const void*src)
+{
+       int err;
+       struct mmc *mmc = find_mmc_device(dev_num);
+       lbaint_t cur, blocks_todo = blkcnt;
+
+       if (!mmc)
+               return -1;
+
+       err = mmc_set_blocklen(mmc, mmc->write_bl_len);
+       if (err) {
+               printf("set write bl len failed\n\r");
+               return err;
        }
 
+       do {
+               /* The 65535 constraint comes from some hardware has
+                * only 16 bit width block number counter */
+               cur = (blocks_todo > 65535) ? 65535 : blocks_todo;
+               if(mmc_write_blocks(mmc, start, cur, src) != cur)
+                       return -1;
+               blocks_todo -= cur;
+               start += cur;
+               src += cur * mmc->write_bl_len;
+       } while (blocks_todo > 0);
        return blkcnt;
 }
 
-- 
1.7.0.4

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