Commit 9e8987ac authored by Charles Keepax's avatar Charles Keepax Committed by Mark Brown

spi: spi-mxs: Fix mapping from vmalloc-ed buffer to scatter list

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: default avatarCharles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 617100c2
...@@ -182,7 +182,6 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi, ...@@ -182,7 +182,6 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi,
int min, ret; int min, ret;
u32 ctrl0; u32 ctrl0;
struct page *vm_page; struct page *vm_page;
void *sg_buf;
struct { struct {
u32 pio[4]; u32 pio[4];
struct scatterlist sg; struct scatterlist sg;
...@@ -232,13 +231,14 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi, ...@@ -232,13 +231,14 @@ static int mxs_spi_txrx_dma(struct mxs_spi *spi,
ret = -ENOMEM; ret = -ENOMEM;
goto err_vmalloc; 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 { } 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, ret = dma_map_sg(ssp->dev, &dma_xfer[sg_count].sg, 1,
(flags & TXRX_WRITE) ? DMA_TO_DEVICE : DMA_FROM_DEVICE); (flags & TXRX_WRITE) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
......
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