[PATCH 16/16] ata: ahci: allocate memory in one call in ahci_init_port()

[Denis Orlov]

Memory allocated with dma_alloc_coherent() is aligned by page size.
Calling it multiple times leads to unnecessary fragmentation and
overhead considering that we are actually able to allocate all the
memory that we need at once by issuing only one call.

Signed-off-by: Denis Orlov <denorl2009 at gmail.com>
---
 drivers/ata/ahci.c | 40 ++++++++++++++--------------------------
 1 file changed, 14 insertions(+), 26 deletions(-)

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 24098ada08..f707efb50f 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -273,6 +273,8 @@ static int ahci_write(struct ata_port *ata, const void *buf, sector_t block,
 static int ahci_init_port(struct ahci_port *ahci_port)
 {
 	u32 val, cmd;
+	void *mem;
+	dma_addr_t mem_dma;
 	int ret;
 
 	/* make sure port is not active */
@@ -290,16 +292,17 @@ static int ahci_init_port(struct ahci_port *ahci_port)
 		mdelay(500);
 	}
 
+	mem = dma_alloc_coherent(AHCI_PORT_PRIV_DMA_SZ, &mem_dma);
+	if (!mem) {
+		return -ENOMEM;
+	}
+
 	/*
 	 * First item in chunk of DMA memory: 32-slot command list,
 	 * 32 bytes each in size
 	 */
-	ahci_port->cmd_slot = dma_alloc_coherent(AHCI_CMD_LIST_SZ,
-						  &ahci_port->cmd_slot_dma);
-	if (!ahci_port->cmd_slot) {
-		ret = -ENOMEM;
-		goto err_alloc;
-	}
+	ahci_port->cmd_slot = mem;
+	ahci_port->cmd_slot_dma = mem_dma;
 
 	ahci_port_debug(ahci_port, "cmd_slot = 0x%p (0x%pa)\n",
 			ahci_port->cmd_slot, ahci_port->cmd_slot_dma);
@@ -307,22 +310,15 @@ static int ahci_init_port(struct ahci_port *ahci_port)
 	/*
 	 * Second item: Received-FIS area
 	 */
-	ahci_port->rx_fis = dma_alloc_coherent(AHCI_RX_FIS_SZ, &ahci_port->rx_fis_dma);
-	if (!ahci_port->rx_fis) {
-		ret = -ENOMEM;
-		goto err_alloc1;
-	}
+	ahci_port->rx_fis = mem + AHCI_CMD_SLOT_SZ;
+	ahci_port->rx_fis_dma = mem_dma + AHCI_CMD_SLOT_SZ;
 
 	/*
 	 * Third item: data area for storing a single command
 	 * and its scatter-gather table
 	 */
-	ahci_port->cmd_tbl = dma_alloc_coherent(AHCI_CMD_TBL_SZ,
-						 &ahci_port->cmd_tbl_dma);
-	if (!ahci_port->cmd_tbl) {
-		ret = -ENOMEM;
-		goto err_alloc2;
-	}
+	ahci_port->cmd_tbl = mem + AHCI_CMD_SLOT_SZ + AHCI_RX_FIS_SZ;
+	ahci_port->cmd_tbl_dma = mem_dma + AHCI_CMD_SLOT_SZ + AHCI_RX_FIS_SZ;
 
 	ahci_port_debug(ahci_port, "cmd_tbl = 0x%p (0x%pa)\n",
 			ahci_port->cmd_tbl, ahci_port->cmd_tbl_dma);
@@ -418,15 +414,7 @@ static int ahci_init_port(struct ahci_port *ahci_port)
 	ret = -ENODEV;
 
 err_init:
-	dma_free_coherent(ahci_port->cmd_tbl, ahci_port->cmd_tbl_dma,
-			  AHCI_CMD_TBL_SZ);
-err_alloc2:
-	dma_free_coherent(ahci_port->rx_fis, ahci_port->rx_fis_dma,
-			  AHCI_RX_FIS_SZ);
-err_alloc1:
-	dma_free_coherent(ahci_port->cmd_slot, ahci_port->cmd_slot_dma,
-			  AHCI_CMD_LIST_SZ);
-err_alloc:
+	dma_free_coherent(mem, mem_dma, AHCI_PORT_PRIV_DMA_SZ);
 	return ret;
 }
 
-- 
2.20.1