[PATCH RFC 15/31] mmc: sdhci: convert ADMA descriptors to a coherent allocation

Rather than using the streaming API, use the coherent allocator to
provide this memory, thereby eliminating cache flushing of it each
time we map and unmap it.  This results in a 7.5% increase in
transfer speed with a UHS-1 card operating in 3.3v mode at a clock
of 49.5MHz.

Signed-off-by: Russell King <redacted>
=-DO NOT APPLY-=
 drivers/mmc/host/sdhci.c | 43 ++++++++++++++++++++++---------------------
 1 file changed, 22 insertions(+), 21 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index e918e17c39e4..d046b4eee335 100644

=-DO NOT APPLY-= a/drivers/mmc/host/sdhci.c
=+DO NOT APPLY+= b/drivers/mmc/host/sdhci.c

@@ -44,6 +44,8 @@
 
 #define MAX_TUNING_LOOP 40
 

=+DO NOT APPLY+=#define ADMA_SIZE	((128 * 2 + 1) * 4)
=+DO NOT APPLY+=
 static unsigned int debug_quirks = 0;
 static unsigned int debug_quirks2;
 

@@ -481,11 +483,6 @@ static int sdhci_adma_table_pre(struct sdhci_host *host,
 	else
 		direction = DMA_TO_DEVICE;
 
-	/*
-	 * The ADMA descriptor table is mapped further down as we
-	 * need to fill it with data first.
-	 */
-
 	host->align_addr = dma_map_single(mmc_dev(host->mmc),
 		host->align_buffer, 128 * 4, direction);
 	if (dma_mapping_error(mmc_dev(host->mmc), host->align_addr))

@@ -546,7 +543,7 @@ static int sdhci_adma_table_pre(struct sdhci_host *host,
 		 * If this triggers then we have a calculation bug
 		 * somewhere. :/
 		 */
-		WARN_ON((desc - host->adma_desc) > (128 * 2 + 1) * 4);

=+DO NOT APPLY+=		WARN_ON((desc - host->adma_desc) > ADMA_SIZE);
 	}
 
 	if (host->quirks & SDHCI_QUIRK_NO_ENDATTR_IN_NOPDESC) {

@@ -574,17 +571,8 @@ static int sdhci_adma_table_pre(struct sdhci_host *host,
 			host->align_addr, 128 * 4, direction);
 	}
 
-	host->adma_addr = dma_map_single(mmc_dev(host->mmc),
-		host->adma_desc, (128 * 2 + 1) * 4, DMA_TO_DEVICE);
-	if (dma_mapping_error(mmc_dev(host->mmc), host->adma_addr))
-		goto unmap_entries;
-	BUG_ON(host->adma_addr & 0x3);
-
 	return 0;
 
-unmap_entries:
-	dma_unmap_sg(mmc_dev(host->mmc), data->sg,
-		data->sg_len, direction);
 unmap_align:
 	dma_unmap_single(mmc_dev(host->mmc), host->align_addr,
 		128 * 4, direction);

@@ -609,9 +597,6 @@ static void sdhci_adma_table_post(struct sdhci_host *host,
 	else
 		direction = DMA_TO_DEVICE;
 
-	dma_unmap_single(mmc_dev(host->mmc), host->adma_addr,
-		(128 * 2 + 1) * 4, DMA_TO_DEVICE);
-
 	dma_unmap_single(mmc_dev(host->mmc), host->align_addr,
 		128 * 4, direction);
 

@@ -2854,15 +2839,29 @@ int sdhci_add_host(struct sdhci_host *host)
 		 * (128) and potentially one alignment transfer for
 		 * each of those entries.
 		 */
-		host->adma_desc = kmalloc((128 * 2 + 1) * 4, GFP_KERNEL);

=+DO NOT APPLY+=		host->adma_desc = dma_alloc_coherent(mmc_dev(host->mmc),
=+DO NOT APPLY+=						     ADMA_SIZE, &host->adma_addr,
=+DO NOT APPLY+=						     GFP_KERNEL);
 		host->align_buffer = kmalloc(128 * 4, GFP_KERNEL);
 		if (!host->adma_desc || !host->align_buffer) {
-			kfree(host->adma_desc);
=+DO NOT APPLY+=			dma_free_coherent(mmc_dev(host->mmc), ADMA_SIZE,
=+DO NOT APPLY+=					  host->adma_desc, host->adma_addr);
 			kfree(host->align_buffer);
 			pr_warning("%s: Unable to allocate ADMA "
 				"buffers. Falling back to standard DMA.\n",
 				mmc_hostname(mmc));
 			host->flags &= ~SDHCI_USE_ADMA;
=+DO NOT APPLY+=			host->adma_desc = NULL;
=+DO NOT APPLY+=			host->align_buffer = NULL;
=+DO NOT APPLY+=		} else if (host->adma_addr & 3) {
=+DO NOT APPLY+=			pr_warning("%s: unable to allocate aligned ADMA descriptor\n",
=+DO NOT APPLY+=				   mmc_hostname(mmc));
=+DO NOT APPLY+=			host->flags &= ~SDHCI_USE_ADMA;
=+DO NOT APPLY+=			dma_free_coherent(mmc_dev(host->mmc), ADMA_SIZE,
=+DO NOT APPLY+=					  host->adma_desc, host->adma_addr);
=+DO NOT APPLY+=			kfree(host->align_buffer);
=+DO NOT APPLY+=			host->adma_desc = NULL;
=+DO NOT APPLY+=			host->align_buffer = NULL;
 		}
 	}
 

@@ -3339,7 +3338,9 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
 		regulator_put(host->vqmmc);
 	}
 
-	kfree(host->adma_desc);

=+DO NOT APPLY+=	if (host->adma_desc)
=+DO NOT APPLY+=		dma_free_coherent(mmc_dev(host->mmc), ADMA_SIZE,
=+DO NOT APPLY+=				  host->adma_desc, host->adma_addr);
 	kfree(host->align_buffer);
 
 	host->adma_desc = NULL;
-- 
1.8.3.1