sfc: Use fixed-size buffers for MCDI NVRAM requests

The low-level MCDI code always uses 32-bit MMIO operations, and
callers must pad input and output buffers to multiples of 4 bytes.
The MCDI NVRAM functions are not doing this.  Also, their buffers are
declared as variable-length arrays with no explicit maximum length.

Switch to a fixed buffer size based on the chunk size used by the
MTD driver (which is a multiple of 4).

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 3 deletions

diff --git a/drivers/net/sfc/mtd.c b/drivers/net/sfc/mtd.c
index 3a464529a46b..407bbaddfea6 100644
--- a/drivers/net/sfc/mtd.c
+++ b/drivers/net/sfc/mtd.c
@@ -23,7 +23,6 @@
 #include "mcdi_pcol.h"
 
 #define EFX_SPI_VERIFY_BUF_LEN 16
-#define EFX_MCDI_CHUNK_LEN 128
 
 struct efx_mtd_partition {
         struct mtd_info mtd;
@@ -428,7 +427,7 @@ static int siena_mtd_read(struct mtd_info *mtd, loff_t start,
         int rc = 0;
 
         while (offset < end) {
-                chunk = min_t(size_t, end - offset, EFX_MCDI_CHUNK_LEN);
+                chunk = min_t(size_t, end - offset, EFX_MCDI_NVRAM_LEN_MAX);
                 rc = efx_mcdi_nvram_read(efx, part->mcdi.nvram_type, offset,
                                          buffer, chunk);
                 if (rc)
@@ -491,7 +490,7 @@ static int siena_mtd_write(struct mtd_info *mtd, loff_t start,
         }
 
         while (offset < end) {
-                chunk = min_t(size_t, end - offset, EFX_MCDI_CHUNK_LEN);
+                chunk = min_t(size_t, end - offset, EFX_MCDI_NVRAM_LEN_MAX);
                 rc = efx_mcdi_nvram_write(efx, part->mcdi.nvram_type, offset,
                                           buffer, chunk);
                 if (rc)