From: Jérôme Pouiller <jerome.pouiller@xxxxxxxxxx>
Using DMA with stack allocated buffers is not supported, whatever the
value of CONFIG_VMAP_STACK.
Signed-off-by: Jérôme Pouiller <jerome.pouiller@xxxxxxxxxx>
---
drivers/staging/wfx/hwio.c | 12 ------------
drivers/staging/wfx/hwio.h | 4 ++++
2 files changed, 4 insertions(+), 12 deletions(-)
diff --git a/drivers/staging/wfx/hwio.c b/drivers/staging/wfx/hwio.c
index 30eb888830d2..393bcb1e2f4e 100644
--- a/drivers/staging/wfx/hwio.c
+++ b/drivers/staging/wfx/hwio.c
@@ -14,18 +14,6 @@
#include "bus.h"
#include "traces.h"
-/*
- * Internal helpers.
- *
- * About CONFIG_VMAP_STACK:
- * When CONFIG_VMAP_STACK is enabled, it is not possible to run DMA on stack
- * allocated data. Functions below that work with registers (aka functions
- * ending with "32") automatically reallocate buffers with kmalloc. However,
- * functions that work with arbitrary length buffers let's caller to handle
- * memory location. In doubt, enable CONFIG_DEBUG_SG to detect badly located
- * buffer.
- */
-
static int read32(struct wfx_dev *wdev, int reg, u32 *val)
{
int ret;
diff --git a/drivers/staging/wfx/hwio.h b/drivers/staging/wfx/hwio.h
index ff09575dd1af..d34baae47017 100644
--- a/drivers/staging/wfx/hwio.h
+++ b/drivers/staging/wfx/hwio.h
@@ -12,6 +12,10 @@
struct wfx_dev;
+/* Caution: in the functions below, 'buf' will used with a DMA. So, it must be
+ * kmalloc'd (do not use stack allocated buffers). In doubt, enable
+ * CONFIG_DEBUG_SG to detect badly located buffer.
+ */
int wfx_data_read(struct wfx_dev *wdev, void *buf, size_t buf_len);
int wfx_data_write(struct wfx_dev *wdev, const void *buf, size_t buf_len);
--
2.34.1
