Unnecessarily mapping and unmapping the align buffer for SD cards is
expensive: performance measurements on iMX6 show that this gives a hit
of 10% on hdparm buffered disk reads.
MMC/SD card IO comes from the mm/vfs which gives us page based IO, so
for this case, the align buffer is not going to be used. However, we
still map and unmap this buffer.
Eliminate this by switching the align buffer to be a DMA coherent
buffer, which needs no DMA maintenance to access the buffer.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org # v4.5+
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
static int sdhci_adma_table_pre(struct sdhci_host *host,
struct mmc_data *data)
{
static int sdhci_adma_table_pre(struct sdhci_host *host,
struct mmc_data *data)
{
void *desc;
void *align;
dma_addr_t addr;
void *desc;
void *align;
dma_addr_t addr;
* We currently guess that it is LE.
*/
* We currently guess that it is LE.
*/
- if (data->flags & MMC_DATA_READ)
- direction = DMA_FROM_DEVICE;
- else
- direction = DMA_TO_DEVICE;
-
- host->align_addr = dma_map_single(mmc_dev(host->mmc),
- host->align_buffer, host->align_buffer_sz, direction);
- if (dma_mapping_error(mmc_dev(host->mmc), host->align_addr))
- goto fail;
- BUG_ON(host->align_addr & SDHCI_ADMA2_MASK);
-
host->sg_count = sdhci_pre_dma_transfer(host, data);
if (host->sg_count < 0)
host->sg_count = sdhci_pre_dma_transfer(host, data);
if (host->sg_count < 0)
desc = host->adma_table;
align = host->align_buffer;
desc = host->adma_table;
align = host->align_buffer;
/* nop, end, valid */
sdhci_adma_write_desc(host, desc, 0, 0, ADMA2_NOP_END_VALID);
}
/* nop, end, valid */
sdhci_adma_write_desc(host, desc, 0, 0, ADMA2_NOP_END_VALID);
}
-
- /*
- * Resync align buffer as we might have changed it.
- */
- if (data->flags & MMC_DATA_WRITE) {
- dma_sync_single_for_device(mmc_dev(host->mmc),
- host->align_addr, host->align_buffer_sz, direction);
- }
-
-
-unmap_align:
- dma_unmap_single(mmc_dev(host->mmc), host->align_addr,
- host->align_buffer_sz, direction);
-fail:
- return -EINVAL;
}
static void sdhci_adma_table_post(struct sdhci_host *host,
}
static void sdhci_adma_table_post(struct sdhci_host *host,
else
direction = DMA_TO_DEVICE;
else
direction = DMA_TO_DEVICE;
- dma_unmap_single(mmc_dev(host->mmc), host->align_addr,
- host->align_buffer_sz, direction);
-
/* Do a quick scan of the SG list for any unaligned mappings */
has_unaligned = false;
for_each_sg(data->sg, sg, host->sg_count, i)
/* Do a quick scan of the SG list for any unaligned mappings */
has_unaligned = false;
for_each_sg(data->sg, sg, host->sg_count, i)
&host->adma_addr,
GFP_KERNEL);
host->align_buffer_sz = SDHCI_MAX_SEGS * SDHCI_ADMA2_ALIGN;
&host->adma_addr,
GFP_KERNEL);
host->align_buffer_sz = SDHCI_MAX_SEGS * SDHCI_ADMA2_ALIGN;
- host->align_buffer = kmalloc(host->align_buffer_sz, GFP_KERNEL);
+ host->align_buffer = dma_alloc_coherent(mmc_dev(mmc),
+ host->align_buffer_sz,
+ &host->align_addr,
+ GFP_KERNEL);
if (!host->adma_table || !host->align_buffer) {
if (host->adma_table)
dma_free_coherent(mmc_dev(mmc),
host->adma_table_sz,
host->adma_table,
host->adma_addr);
if (!host->adma_table || !host->align_buffer) {
if (host->adma_table)
dma_free_coherent(mmc_dev(mmc),
host->adma_table_sz,
host->adma_table,
host->adma_addr);
- kfree(host->align_buffer);
+ if (host->align_buffer)
+ dma_free_coherent(mmc_dev(mmc),
+ host->align_buffer_sz,
+ host->align_buffer,
+ host->align_addr);
pr_warn("%s: Unable to allocate ADMA buffers - falling back to standard DMA\n",
mmc_hostname(mmc));
host->flags &= ~SDHCI_USE_ADMA;
pr_warn("%s: Unable to allocate ADMA buffers - falling back to standard DMA\n",
mmc_hostname(mmc));
host->flags &= ~SDHCI_USE_ADMA;
host->flags &= ~SDHCI_USE_ADMA;
dma_free_coherent(mmc_dev(mmc), host->adma_table_sz,
host->adma_table, host->adma_addr);
host->flags &= ~SDHCI_USE_ADMA;
dma_free_coherent(mmc_dev(mmc), host->adma_table_sz,
host->adma_table, host->adma_addr);
- kfree(host->align_buffer);
+ dma_free_coherent(mmc_dev(mmc), host->align_buffer_sz,
+ host->align_buffer, host->align_addr);
host->adma_table = NULL;
host->align_buffer = NULL;
}
host->adma_table = NULL;
host->align_buffer = NULL;
}
+
+ /* dma_alloc_coherent returns page aligned and sized buffers */
+ BUG_ON(host->align_addr & SDHCI_ADMA2_MASK);
if (host->adma_table)
dma_free_coherent(mmc_dev(mmc), host->adma_table_sz,
host->adma_table, host->adma_addr);
if (host->adma_table)
dma_free_coherent(mmc_dev(mmc), host->adma_table_sz,
host->adma_table, host->adma_addr);
- kfree(host->align_buffer);
+ if (host->align_buffer)
+ dma_free_coherent(mmc_dev(mmc), host->align_buffer_sz,
+ host->align_buffer, host->align_addr);
host->adma_table = NULL;
host->align_buffer = NULL;
host->adma_table = NULL;
host->align_buffer = NULL;