diff mbox

[2/2] spi: spi-mxs: Fix mapping from vmalloc-ed buffer to scatter list

Message ID 1416215672-31554-2-git-send-email-ckeepax@opensource.wolfsonmicro.com (mailing list archive)
State Accepted
Commit 9e8987acf051e48fc0e228b6f38c47a75352c58b
Headers show

Commit Message

Charles Keepax Nov. 17, 2014, 9:14 a.m. UTC 
We can only use page_address on memory that has been mapped using kmap,
when the buffer passed to the SPI has been allocated by vmalloc the page
has not necessarily been mapped through kmap. This means sometimes
page_address will return NULL causing the pointer we pass to sg_init_one
to be invalid. Currently, this issue doesn't show up on the MXS
architecture as the defconfig defines CONFIG_HIGHMEM=n which means all
pages are mapped. For the sake of robustness though it is best to
correct the issue.

As we only call page_address so that we can pass a virtual address to
sg_init_one which will eventually call virt_to_page on it, fix this
by calling sg_set_page directly rather then relying on the sg_init_one
helper.

Note this patch is only build tested as I don't have an MXS system to
test on.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
---
 drivers/spi/spi-mxs.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

Comments

Mark Brown Nov. 24, 2014, 6:58 p.m. UTC | #1 
On Mon, Nov 17, 2014 at 09:14:32AM +0000, Charles Keepax wrote:
> We can only use page_address on memory that has been mapped using kmap,
> when the buffer passed to the SPI has been allocated by vmalloc the page
> has not necessarily been mapped through kmap. This means sometimes

Applied, thanks.
diff mbox

Patch

diff --git a/drivers/spi/spi-mxs.c b/drivers/spi/spi-mxs.c
index a9e72f9..06a1154 100644
--- a/drivers/spi/spi-mxs.c
+++ b/drivers/spi/spi-mxs.c
@@ -182,7 +182,6 @@  static int mxs_spi_txrx_dma(struct mxs_spi *spi,
 	int min, ret;
 	u32 ctrl0;
 	struct page *vm_page;
-	void *sg_buf;
 	struct {
 		u32			pio[4];
 		struct scatterlist	sg;
@@ -232,13 +231,14 @@  static int mxs_spi_txrx_dma(struct mxs_spi *spi,
 				ret = -ENOMEM;
 				goto err_vmalloc;
 			}
-			sg_buf = page_address(vm_page) +
-				((size_t)buf & ~PAGE_MASK);
+
+			sg_init_table(&dma_xfer[sg_count].sg, 1);
+			sg_set_page(&dma_xfer[sg_count].sg, vm_page,
+				    min, offset_in_page(buf));
 		} else {
-			sg_buf = buf;
+			sg_init_one(&dma_xfer[sg_count].sg, buf, min);
 		}
 
-		sg_init_one(&dma_xfer[sg_count].sg, sg_buf, min);
 		ret = dma_map_sg(ssp->dev, &dma_xfer[sg_count].sg, 1,
 			(flags & TXRX_WRITE) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);