diff options
| -rw-r--r-- | Documentation/i2c/DMA-considerations | 10 | ||||
| -rw-r--r-- | drivers/i2c/busses/i2c-sh_mobile.c | 2 | ||||
| -rw-r--r-- | drivers/i2c/i2c-core-base.c | 11 | ||||
| -rw-r--r-- | include/linux/i2c.h | 2 |
4 files changed, 15 insertions, 10 deletions
diff --git a/Documentation/i2c/DMA-considerations b/Documentation/i2c/DMA-considerations index 966610aa4620..203002054120 100644 --- a/Documentation/i2c/DMA-considerations +++ b/Documentation/i2c/DMA-considerations @@ -50,10 +50,14 @@ bounce buffer. But you don't need to care about that detail, just use the returned buffer. If NULL is returned, the threshold was not met or a bounce buffer could not be allocated. Fall back to PIO in that case. -In any case, a buffer obtained from above needs to be released. It ensures data -is copied back to the message and a potentially used bounce buffer is freed:: +In any case, a buffer obtained from above needs to be released. Another helper +function ensures a potentially used bounce buffer is freed:: - i2c_release_dma_safe_msg_buf(msg, dma_buf); + i2c_put_dma_safe_msg_buf(dma_buf, msg, xferred); + +The last argument 'xferred' controls if the buffer is synced back to the +message or not. No syncing is needed in cases setting up DMA had an error and +there was no data transferred. The bounce buffer handling from the core is generic and simple. It will always allocate a new bounce buffer. If you want a more sophisticated handling (e.g. diff --git a/drivers/i2c/busses/i2c-sh_mobile.c b/drivers/i2c/busses/i2c-sh_mobile.c index 439e8778f849..279d0e5bd433 100644 --- a/drivers/i2c/busses/i2c-sh_mobile.c +++ b/drivers/i2c/busses/i2c-sh_mobile.c @@ -507,7 +507,7 @@ static void sh_mobile_i2c_dma_callback(void *data) pd->pos = pd->msg->len; pd->stop_after_dma = true; - i2c_release_dma_safe_msg_buf(pd->msg, pd->dma_buf); + i2c_put_dma_safe_msg_buf(pd->dma_buf, pd->msg, true); iic_set_clr(pd, ICIC, 0, ICIC_TDMAE | ICIC_RDMAE); } diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index f15737763608..9ee9a15e7134 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -2293,21 +2293,22 @@ u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold) EXPORT_SYMBOL_GPL(i2c_get_dma_safe_msg_buf); /** - * i2c_release_dma_safe_msg_buf - release DMA safe buffer and sync with i2c_msg - * @msg: the message to be synced with + * i2c_put_dma_safe_msg_buf - release DMA safe buffer and sync with i2c_msg * @buf: the buffer obtained from i2c_get_dma_safe_msg_buf(). May be NULL. + * @msg: the message which the buffer corresponds to + * @xferred: bool saying if the message was transferred */ -void i2c_release_dma_safe_msg_buf(struct i2c_msg *msg, u8 *buf) +void i2c_put_dma_safe_msg_buf(u8 *buf, struct i2c_msg *msg, bool xferred) { if (!buf || buf == msg->buf) return; - if (msg->flags & I2C_M_RD) + if (xferred && msg->flags & I2C_M_RD) memcpy(msg->buf, buf, msg->len); kfree(buf); } -EXPORT_SYMBOL_GPL(i2c_release_dma_safe_msg_buf); +EXPORT_SYMBOL_GPL(i2c_put_dma_safe_msg_buf); MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>"); MODULE_DESCRIPTION("I2C-Bus main module"); diff --git a/include/linux/i2c.h b/include/linux/i2c.h index b79387fd57da..65b4eaed1d96 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -855,7 +855,7 @@ static inline u8 i2c_8bit_addr_from_msg(const struct i2c_msg *msg) } u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold); -void i2c_release_dma_safe_msg_buf(struct i2c_msg *msg, u8 *buf); +void i2c_put_dma_safe_msg_buf(u8 *buf, struct i2c_msg *msg, bool xferred); int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr); /** |