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authorWolfram Sang <wsa+renesas@sang-engineering.com>2019-03-12 13:44:42 +0100
committerWolfram Sang <wsa@the-dreams.de>2019-03-13 18:03:26 +0100
commitbf263c35b2ebe7f1674205f6b36487250299b5a7 (patch)
treed281179a1dfafd96a655cd4234e1238179973113 /drivers/i2c
parenti2c: i2c-stm32f7: Fix SDADEL minimum formula (diff)
downloadlinux-bf263c35b2ebe7f1674205f6b36487250299b5a7.tar.xz
linux-bf263c35b2ebe7f1674205f6b36487250299b5a7.zip
i2c: add extra check to safe DMA buffer helper
Make sure we report 'no buffer' for 0-length messages. This can only happen if threshold is set to 0 which is kind of bogus but we should still handle this situation. Update the docs and add a debug message to educate callers of this function. Reported-by: Hsin-Yi Wang <hsinyi@chromium.org> Fixes: e94bc5d18be0 ("i2c: add helpers to ease DMA handling") Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Reviewed-by: Hsin-Yi Wang <hsinyi@chromium.org> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/i2c-core-base.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index cb6c5cb0df0b..38af18645133 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -2258,7 +2258,8 @@ EXPORT_SYMBOL(i2c_put_adapter);
/**
* i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg
* @msg: the message to be checked
- * @threshold: the minimum number of bytes for which using DMA makes sense
+ * @threshold: the minimum number of bytes for which using DMA makes sense.
+ * Should at least be 1.
*
* Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO.
* Or a valid pointer to be used with DMA. After use, release it by
@@ -2268,7 +2269,11 @@ EXPORT_SYMBOL(i2c_put_adapter);
*/
u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold)
{
- if (msg->len < threshold)
+ /* also skip 0-length msgs for bogus thresholds of 0 */
+ if (!threshold)
+ pr_debug("DMA buffer for addr=0x%02x with length 0 is bogus\n",
+ msg->addr);
+ if (msg->len < threshold || msg->len == 0)
return NULL;
if (msg->flags & I2C_M_DMA_SAFE)