[PATCH v3 11/12] dmaengine: at_xdmac: Remove a level of indentation in at_xdmac_tasklet()

Tudor Ambarus
2021-12-15T11:01:59Z

Apart of making the code easier to read, this patch is a prerequisite for
a functional change: tasklets run with interrupts enabled, so we need to
protect atchan->irq_status with spin_lock_irq() otherwise the tasklet can
be interrupted by the IRQ that modifies irq_status. atchan->irq_status
will be protected in a further patch.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
drivers/dma/at_xdmac.c | 70 ++++++++++++++++++++----------------------
1 file changed, 34 insertions(+), 36 deletions(-)

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index abe8c4615e65..ba727751a9f6 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -1667,53 +1667,51 @@ static void at_xdmac_tasklet(struct tasklet_struct *t)
{
struct at_xdmac_chan *atchan = from_tasklet(atchan, t, tasklet);
struct at_xdmac_desc *desc;
+ struct dma_async_tx_descriptor *txd;
u32 error_mask;

dev_dbg(chan2dev(&atchan->chan), "%s: status=0x%08x\n",
__func__, atchan->irq_status);

- error_mask = AT_XDMAC_CIS_RBEIS
- | AT_XDMAC_CIS_WBEIS
- | AT_XDMAC_CIS_ROIS;
-
- if (at_xdmac_chan_is_cyclic(atchan)) {
- at_xdmac_handle_cyclic(atchan);
- } else if ((atchan->irq_status & AT_XDMAC_CIS_LIS)
- || (atchan->irq_status & error_mask)) {
- struct dma_async_tx_descriptor *txd;
-
- if (atchan->irq_status & error_mask)
- at_xdmac_handle_error(atchan);
-
- spin_lock_irq(&atchan->lock);
- desc = list_first_entry(&atchan->xfers_list,
- struct at_xdmac_desc,
- xfer_node);
- dev_vdbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, desc);
- if (!desc->active_xfer) {
- dev_err(chan2dev(&atchan->chan), "Xfer not active: exiting");
- spin_unlock_irq(&atchan->lock);
- return;
- }
+ if (at_xdmac_chan_is_cyclic(atchan))
+ return at_xdmac_handle_cyclic(atchan);

- txd = &desc->tx_dma_desc;
- dma_cookie_complete(txd);
- /* Remove the transfer from the transfer list. */
- list_del(&desc->xfer_node);
- spin_unlock_irq(&atchan->lock);
+ error_mask = AT_XDMAC_CIS_RBEIS | AT_XDMAC_CIS_WBEIS |
+ AT_XDMAC_CIS_ROIS;

- if (txd->flags & DMA_PREP_INTERRUPT)
- dmaengine_desc_get_callback_invoke(txd, NULL);
+ if (!(atchan->irq_status & AT_XDMAC_CIS_LIS) &&
+ !(atchan->irq_status & error_mask))
+ return;

- dma_run_dependencies(txd);
+ if (atchan->irq_status & error_mask)
+ at_xdmac_handle_error(atchan);

- spin_lock_irq(&atchan->lock);
- /* Move the xfer descriptors into the free descriptors list. */
- list_splice_tail_init(&desc->descs_list,
- &atchan->free_descs_list);
- at_xdmac_advance_work(atchan);
+ spin_lock_irq(&atchan->lock);
+ desc = list_first_entry(&atchan->xfers_list, struct at_xdmac_desc,
+ xfer_node);
+ dev_vdbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, desc);
+ if (!desc->active_xfer) {
+ dev_err(chan2dev(&atchan->chan), "Xfer not active: exiting");
spin_unlock_irq(&atchan->lock);
+ return;
}
+
+ txd = &desc->tx_dma_desc;
+ dma_cookie_complete(txd);
+ /* Remove the transfer from the transfer list. */
+ list_del(&desc->xfer_node);
+ spin_unlock_irq(&atchan->lock);
+
+ if (txd->flags & DMA_PREP_INTERRUPT)
+ dmaengine_desc_get_callback_invoke(txd, NULL);
+
+ dma_run_dependencies(txd);
+
+ spin_lock_irq(&atchan->lock);
+ /* Move the xfer descriptors into the free descriptors list. */
+ list_splice_tail_init(&desc->descs_list, &atchan->free_descs_list);
+ at_xdmac_advance_work(atchan);
+ spin_unlock_irq(&atchan->lock);
}

static irqreturn_t at_xdmac_interrupt(int irq, void *dev_id)
--
2.25.1