On 09/17/2018 04:36 PM, Boris Brezillon wrote:
As documented in spi-mem.h, spi_mem_op->data.buf.{in,out} must be
DMA-able, and commit 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx()
API") failed to follow this rule as buffers passed to
->{read,write}_reg() are usually placed on the stack.
Fix that by allocating a scratch buffer and copying the data in there
before passing it to the spi-mem layer.
Fixes: 4120f8d158ef ("mtd: spi-nor: Use the spi_mem_xx() API")
Reported-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
---
Note that the ->{read,write}() path is still buggy since nothing
guarantees that buffers passed by the MTD layer to the SPI NOR layer
are DMA-able, but this is a long-standing issue which we'll have to
address at the spi-nor level (this layer can choose the bounce buffer
size based on nor->page_size).
---
drivers/mtd/devices/m25p80.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index cbfafc453274..3b7fafa4bbd6 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -39,14 +39,22 @@ static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 *val, int len)
struct spi_mem_op op = SPI_MEM_OP(SPI_MEM_OP_CMD(code, 1),
SPI_MEM_OP_NO_ADDR,
SPI_MEM_OP_NO_DUMMY,
- SPI_MEM_OP_DATA_IN(len, val, 1));
+ SPI_MEM_OP_DATA_IN(len, NULL, 1));
+ void *scratchbuf;
int ret;
+ scratchbuf = kmemdup(val, len, GFP_KERNEL);
+ if (!scratchbuf)
+ return -ENOMEM;
+
+ op.data.buf.in = scratchbuf;
ret = spi_mem_exec_op(flash->spimem, &op);
if (ret < 0)
dev_err(&flash->spimem->spi->dev, "error %d reading %x\n", ret,
code);
+ kfree(scratchbuf);
+
Actually this makes things even worse: "unrecognized JEDEC id bytes: b1,
74, 01" since we don't copy scratchbuf to original buffer and kmemdup
before bus read is needless :-)
--
Jarkko
