[PATCH v3 06/12] dmaengine: at_xdmac: Move the free desc to the tail of the desc list

Tudor Ambarus
2021-12-15T11:01:41Z

Move the free desc to the tail of the list, so that the sequence of
descriptors is more track-able in case of debug. One would know which
descriptor should come next and could easier catch concurrency over
descriptors for example. virt-dma uses list_splice_tail_init() as well,
follow the core driver.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
drivers/dma/at_xdmac.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index d5b37459f906..b6547f1b5645 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -729,7 +729,8 @@ at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
if (!desc) {
dev_err(chan2dev(chan), "can't get descriptor\n");
if (first)
- list_splice_init(&first->descs_list, &atchan->free_descs_list);
+ list_splice_tail_init(&first->descs_list,
+ &atchan->free_descs_list);
goto spin_unlock;
}

@@ -817,7 +818,8 @@ at_xdmac_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf_addr,
if (!desc) {
dev_err(chan2dev(chan), "can't get descriptor\n");
if (first)
- list_splice_init(&first->descs_list, &atchan->free_descs_list);
+ list_splice_tail_init(&first->descs_list,
+ &atchan->free_descs_list);
spin_unlock_irqrestore(&atchan->lock, irqflags);
return NULL;
}
@@ -1051,8 +1053,8 @@ at_xdmac_prep_interleaved(struct dma_chan *chan,
src_addr, dst_addr,
xt, chunk);
if (!desc) {
- list_splice_init(&first->descs_list,
- &atchan->free_descs_list);
+ list_splice_tail_init(&first->descs_list,
+ &atchan->free_descs_list);
return NULL;
}

@@ -1132,7 +1134,8 @@ at_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
if (!desc) {
dev_err(chan2dev(chan), "can't get descriptor\n");
if (first)
- list_splice_init(&first->descs_list, &atchan->free_descs_list);
+ list_splice_tail_init(&first->descs_list,
+ &atchan->free_descs_list);
return NULL;
}

@@ -1308,8 +1311,8 @@ at_xdmac_prep_dma_memset_sg(struct dma_chan *chan, struct scatterlist *sgl,
sg_dma_len(sg),
value);
if (!desc && first)
- list_splice_init(&first->descs_list,
- &atchan->free_descs_list);
+ list_splice_tail_init(&first->descs_list,
+ &atchan->free_descs_list);

if (!first)
first = desc;
@@ -1701,7 +1704,8 @@ static void at_xdmac_tasklet(struct tasklet_struct *t)

spin_lock_irq(&atchan->lock);
/* Move the xfer descriptors into the free descriptors list. */
- list_splice_init(&desc->descs_list, &atchan->free_descs_list);
+ list_splice_tail_init(&desc->descs_list,
+ &atchan->free_descs_list);
at_xdmac_advance_work(atchan);
spin_unlock_irq(&atchan->lock);
}
@@ -1850,7 +1854,8 @@ static int at_xdmac_device_terminate_all(struct dma_chan *chan)
/* Cancel all pending transfers. */
list_for_each_entry_safe(desc, _desc, &atchan->xfers_list, xfer_node) {
list_del(&desc->xfer_node);
- list_splice_init(&desc->descs_list, &atchan->free_descs_list);
+ list_splice_tail_init(&desc->descs_list,
+ &atchan->free_descs_list);
}

clear_bit(AT_XDMAC_CHAN_IS_PAUSED, &atchan->status);
--
2.25.1