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authorKyungsik Lee <kyungsik.lee@lge.com>2012-08-03 00:58:03 +0000
committerChris Ball <cjb@laptop.org>2012-09-19 16:29:42 +0800
commit1a41313e7f8c5b724a2e3ff66558dbe811844423 (patch)
treec6a536fc3288f76049b6301c7c7a4e8ce553e067 /drivers/mmc
parent8f63795c60ef5bc3dbfcbf19c1ac64ed79d23c62 (diff)
downloadlinux-1a41313e7f8c5b724a2e3ff66558dbe811844423.tar.bz2
mmc: core: Remove bounce buffer in mmc_send_cxd_data()
It is expected that Extended CSD register (the size of this register is larger than CID/CSD) will be referenced more frequently as more fields have been added to Extended CSD and it seems that it is not a good option to double the memory used. This patch is intended to avoid the use of bounce buffer for reading Extended CSD register in mmc_send_cxd_data(). It will provide a better performance gain by removing memcpy() overhead for a half KiB and a redundant bounce buffer allocated repeatedly at the cost of providing DMA-capable buffer from upper caller (but on-stack buffer is allowed with no performance gain). Signed-off-by: Kyungsik Lee <kyungsik.lee@lge.com> Reviewed-by: Venkatraman S <svenkatr@ti.com> Signed-off-by: Chris Ball <cjb@laptop.org>
Diffstat (limited to 'drivers/mmc')
-rw-r--r--drivers/mmc/core/mmc_ops.c58
1 files changed, 42 insertions, 16 deletions
diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
index 0ed2cc5f35b6..225371a28861 100644
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -230,6 +230,10 @@ mmc_send_cxd_native(struct mmc_host *host, u32 arg, u32 *cxd, int opcode)
return 0;
}
+/*
+ * NOTE: void *buf, caller for the buf is required to use DMA-capable
+ * buffer or on-stack buffer (with some overhead in callee).
+ */
static int
mmc_send_cxd_data(struct mmc_card *card, struct mmc_host *host,
u32 opcode, void *buf, unsigned len)
@@ -239,13 +243,19 @@ mmc_send_cxd_data(struct mmc_card *card, struct mmc_host *host,
struct mmc_data data = {0};
struct scatterlist sg;
void *data_buf;
+ int is_on_stack;
- /* dma onto stack is unsafe/nonportable, but callers to this
- * routine normally provide temporary on-stack buffers ...
- */
- data_buf = kmalloc(len, GFP_KERNEL);
- if (data_buf == NULL)
- return -ENOMEM;
+ is_on_stack = object_is_on_stack(buf);
+ if (is_on_stack) {
+ /*
+ * dma onto stack is unsafe/nonportable, but callers to this
+ * routine normally provide temporary on-stack buffers ...
+ */
+ data_buf = kmalloc(len, GFP_KERNEL);
+ if (!data_buf)
+ return -ENOMEM;
+ } else
+ data_buf = buf;
mrq.cmd = &cmd;
mrq.data = &data;
@@ -280,8 +290,10 @@ mmc_send_cxd_data(struct mmc_card *card, struct mmc_host *host,
mmc_wait_for_req(host, &mrq);
- memcpy(buf, data_buf, len);
- kfree(data_buf);
+ if (is_on_stack) {
+ memcpy(buf, data_buf, len);
+ kfree(data_buf);
+ }
if (cmd.error)
return cmd.error;
@@ -294,24 +306,32 @@ mmc_send_cxd_data(struct mmc_card *card, struct mmc_host *host,
int mmc_send_csd(struct mmc_card *card, u32 *csd)
{
int ret, i;
+ u32 *csd_tmp;
if (!mmc_host_is_spi(card->host))
return mmc_send_cxd_native(card->host, card->rca << 16,
csd, MMC_SEND_CSD);
- ret = mmc_send_cxd_data(card, card->host, MMC_SEND_CSD, csd, 16);
+ csd_tmp = kmalloc(16, GFP_KERNEL);
+ if (!csd_tmp)
+ return -ENOMEM;
+
+ ret = mmc_send_cxd_data(card, card->host, MMC_SEND_CSD, csd_tmp, 16);
if (ret)
- return ret;
+ goto err;
for (i = 0;i < 4;i++)
- csd[i] = be32_to_cpu(csd[i]);
+ csd[i] = be32_to_cpu(csd_tmp[i]);
- return 0;
+err:
+ kfree(csd_tmp);
+ return ret;
}
int mmc_send_cid(struct mmc_host *host, u32 *cid)
{
int ret, i;
+ u32 *cid_tmp;
if (!mmc_host_is_spi(host)) {
if (!host->card)
@@ -320,14 +340,20 @@ int mmc_send_cid(struct mmc_host *host, u32 *cid)
cid, MMC_SEND_CID);
}
- ret = mmc_send_cxd_data(NULL, host, MMC_SEND_CID, cid, 16);
+ cid_tmp = kmalloc(16, GFP_KERNEL);
+ if (!cid_tmp)
+ return -ENOMEM;
+
+ ret = mmc_send_cxd_data(NULL, host, MMC_SEND_CID, cid_tmp, 16);
if (ret)
- return ret;
+ goto err;
for (i = 0;i < 4;i++)
- cid[i] = be32_to_cpu(cid[i]);
+ cid[i] = be32_to_cpu(cid_tmp[i]);
- return 0;
+err:
+ kfree(cid_tmp);
+ return ret;
}
int mmc_send_ext_csd(struct mmc_card *card, u8 *ext_csd)