From 82fe39a6bc7b866fc3ffd838e3c5a4cadb328b04 Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Fri, 24 Aug 2018 16:52:44 +0200 Subject: i2c: refactor function to release a DMA safe buffer 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 Reviewed-by: Niklas Söderlund Signed-off-by: Wolfram Sang --- Documentation/i2c/DMA-considerations | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'Documentation/i2c') 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. -- cgit v1.2.3