[PATCH 22/22] mtd: rawnand: Use dma_alloc_noncoherent() for dma buffer

Baoquan He
2022-02-19T00:59:36Z

Use dma_alloc_noncoherent() instead of directly allocating buffer
from kmalloc with GFP_DMA. DMA API will try to allocate buffer
depending on devices addressing limitation.

[ 42.hyeyoo@gmail.com: Use dma_alloc_noncoherent() instead of
__get_free_page() and update changelog.

As it does not allocate high order buffers, allocate buffer
when needed and free after DMA. ]

Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: christian.koenig@amd.com
Cc: linux-mtd@lists.infradead.org

---
drivers/mtd/nand/raw/marvell_nand.c | 55 ++++++++++++++++++-----------
1 file changed, 34 insertions(+), 21 deletions(-)

diff --git a/drivers/mtd/nand/raw/marvell_nand.c b/drivers/mtd/nand/raw/marvell_nand.c
index 2455a581fd70..c0b64a7e50af 100644
--- a/drivers/mtd/nand/raw/marvell_nand.c
+++ b/drivers/mtd/nand/raw/marvell_nand.c
@@ -860,26 +860,45 @@ static int marvell_nfc_xfer_data_dma(struct marvell_nfc *nfc,
struct dma_async_tx_descriptor *tx;
struct scatterlist sg;
dma_cookie_t cookie;
- int ret;
+ dma_addr_t dma_handle;
+ int ret = 0;

marvell_nfc_enable_dma(nfc);
+
+ /*
+ * DMA must act on length multiple of 32 and this length may be
+ * bigger than the destination buffer. Use this buffer instead
+ * for DMA transfers and then copy the desired amount of data to
+ * the provided buffer.
+ */
+ nfc->dma_buf = dma_alloc_noncoherent(nfc->dev, MAX_CHUNK_SIZE,
+ &dma_handle,
+ direction,
+ GFP_ATOMIC);
+ if (!nfc->dma_buf) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+
/* Prepare the DMA transfer */
- sg_init_one(&sg, nfc->dma_buf, dma_len);
- dma_map_sg(nfc->dma_chan->device->dev, &sg, 1, direction);
- tx = dmaengine_prep_slave_sg(nfc->dma_chan, &sg, 1,
+ tx = dmaengine_prep_slave_single(nfc->dma_chan, dma_handle, dma_len,
direction == DMA_FROM_DEVICE ?
DMA_DEV_TO_MEM : DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT);
if (!tx) {
dev_err(nfc->dev, "Could not prepare DMA S/G list\n");
- return -ENXIO;
+ ret = -ENXIO;
+ goto free;
}

/* Do the task and wait for it to finish */
cookie = dmaengine_submit(tx);
ret = dma_submit_error(cookie);
- if (ret)
- return -EIO;
+ if (ret) {
+ ret = -EIO;
+ goto free;
+ }

dma_async_issue_pending(nfc->dma_chan);
ret = marvell_nfc_wait_cmdd(nfc->selected_chip);
@@ -889,10 +908,16 @@ static int marvell_nfc_xfer_data_dma(struct marvell_nfc *nfc,
dev_err(nfc->dev, "Timeout waiting for DMA (status: %d)\n",
dmaengine_tx_status(nfc->dma_chan, cookie, NULL));
dmaengine_terminate_all(nfc->dma_chan);
- return -ETIMEDOUT;
+ ret = -ETIMEDOUT;
+ goto free;
}

- return 0;
+free:
+ dma_free_noncoherent(nfc->dev, MAX_CHUNK_SIZE, nfc->dma_buf,
+ dma_handle, direction);
+
+out:
+ return ret;
}

static int marvell_nfc_xfer_data_in_pio(struct marvell_nfc *nfc, u8 *in,
@@ -2814,18 +2839,6 @@ static int marvell_nfc_init_dma(struct marvell_nfc *nfc)
goto release_channel;
}

- /*
- * DMA must act on length multiple of 32 and this length may be
- * bigger than the destination buffer. Use this buffer instead
- * for DMA transfers and then copy the desired amount of data to
- * the provided buffer.
- */
- nfc->dma_buf = kmalloc(MAX_CHUNK_SIZE, GFP_KERNEL | GFP_DMA);
- if (!nfc->dma_buf) {
- ret = -ENOMEM;
- goto release_channel;
- }
-
nfc->use_dma = true;

return 0;
--
2.17.2