diff options
Diffstat (limited to 'block/blk-settings.c')
| -rw-r--r-- | block/blk-settings.c | 37 |
1 files changed, 0 insertions, 37 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c index 14397b4c4b53..2ab1967b9716 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -652,43 +652,6 @@ void blk_queue_update_dma_pad(struct request_queue *q, unsigned int mask) EXPORT_SYMBOL(blk_queue_update_dma_pad); /** - * blk_queue_dma_drain - Set up a drain buffer for excess dma. - * @q: the request queue for the device - * @dma_drain_needed: fn which returns non-zero if drain is necessary - * @buf: physically contiguous buffer - * @size: size of the buffer in bytes - * - * Some devices have excess DMA problems and can't simply discard (or - * zero fill) the unwanted piece of the transfer. They have to have a - * real area of memory to transfer it into. The use case for this is - * ATAPI devices in DMA mode. If the packet command causes a transfer - * bigger than the transfer size some HBAs will lock up if there - * aren't DMA elements to contain the excess transfer. What this API - * does is adjust the queue so that the buf is always appended - * silently to the scatterlist. - * - * Note: This routine adjusts max_hw_segments to make room for appending - * the drain buffer. If you call blk_queue_max_segments() after calling - * this routine, you must set the limit to one fewer than your device - * can support otherwise there won't be room for the drain buffer. - */ -int blk_queue_dma_drain(struct request_queue *q, - dma_drain_needed_fn *dma_drain_needed, - void *buf, unsigned int size) -{ - if (queue_max_segments(q) < 2) - return -EINVAL; - /* make room for appending the drain */ - blk_queue_max_segments(q, queue_max_segments(q) - 1); - q->dma_drain_needed = dma_drain_needed; - q->dma_drain_buffer = buf; - q->dma_drain_size = size; - - return 0; -} -EXPORT_SYMBOL_GPL(blk_queue_dma_drain); - -/** * blk_queue_segment_boundary - set boundary rules for segment merging * @q: the request queue for the device * @mask: the memory boundary mask |