Nico Huber has uploaded this change for review.

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linux_spi: Reduce maximum read chunksize

It turned out that older kernels use a single buffer of `bufsiz` bytes
for combined input and output data. So we have to account for the read
command + max 4 address bytes.

Change-Id: Ide50db38af1004fde09a70b15938e77f5e1285ac
Signed-off-by: Nico Huber <nico.huber@secunet.com>
---
M linux_spi.c
1 file changed, 3 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/49/25149/1

diff --git a/linux_spi.c b/linux_spi.c
index 1d3605a..714e612 100644
--- a/linux_spi.c
+++ b/linux_spi.c
@@ -221,8 +221,9 @@
 
 static int linux_spi_read(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len)
 {
-	/* Read buffer is fully utilized for data. */
-	return spi_read_chunked(flash, buf, start, len, max_kernel_buf_size);
+	/* Older kernels use a single buffer for combined input and output
+	   data. So account for longest possible command + address, too. */
+	return spi_read_chunked(flash, buf, start, len, max_kernel_buf_size - 5);
 }
 
 static int linux_spi_write_256(struct flashctx *flash, const uint8_t *buf, unsigned int start, unsigned int len)

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