Hi Wolfram,
Thanks for your patch.
On 2018-08-24 16:52:44 +0200, Wolfram Sang wrote:
> a) rename to 'put' instead of 'release' to match 'get' when obtaining
> the buffer
> b) change the argument order to have the buffer as first argument
> c) add a new argument telling the function if the message was
> transferred. This allows the function to be used also in cases
> where setting up DMA failed, so the buffer needs to be freed without
> syncing to the message buffer.
>
> Also convert the only user.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> ---
> Documentation/i2c/DMA-considerations | 10 +++++++---
> drivers/i2c/busses/i2c-sh_mobile.c | 2 +-
> drivers/i2c/i2c-core-base.c | 11 ++++++-----
> 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..bf40f5c01d15 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 9c7f6f8ceb22..16c35d474398 100644
> --- a/drivers/i2c/busses/i2c-sh_mobile.c
> +++ b/drivers/i2c/busses/i2c-sh_mobile.c
> @@ -515,7 +515,7 @@ 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 5a937109a289..4e381aeff917 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -2302,21 +2302,22 @@ 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@xxxxxxxxxxxxxxxxx>");
> MODULE_DESCRIPTION("I2C-Bus main module");
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index 36f357ecdf67..6f77708544ff 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -861,7 +861,7 @@ 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);
> /**
> --
> 2.11.0
>
--
Regards,
Niklas Söderlund
