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dmaengine: pl330: Return DMA_PAUSED when transaction is paused

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pl330_pause() does not set anything to indicate paused condition which
causes pl330_tx_status() to return DMA_IN_PROGRESS. This breaks 8250
DMA flush after the fix in commit 57e9af7831 ("serial: 8250_dma: Fix
DMA Rx rearm race"). The function comment for pl330_pause() claims
pause is supported but resume is not which is enough for 8250 DMA flush
to work as long as DMA status reports DMA_PAUSED when appropriate.

Add PAUSED state for descriptor and mark BUSY descriptors with PAUSED
in pl330_pause(). Return DMA_PAUSED from pl330_tx_status() when the
descriptor is PAUSED.

Reported-by: Richard Tresidder <rtresidd@electromag.com.au>
Tested-by: Richard Tresidder <rtresidd@electromag.com.au>
Fixes: 88987d2c75 ("dmaengine: pl330: add DMA_PAUSE feature")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/linux-serial/f8a86ecd-64b1-573f-c2fa-59f541083f1a@electromag.com.au/
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230526105434.14959-1-ilpo.jarvinen@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Ilpo Järvinen 2023-05-26 13:54:34 +03:00 committed by Vinod Koul
parent e2dcbc330f
commit 8cda3ececf
1 changed files with 16 additions and 2 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

18
drivers/dma/pl330.c
View file

@ -403,6 +403,12 @@ enum desc_status {
* of a channel can be BUSY at any time. * of a channel can be BUSY at any time.
*/ */
BUSY, BUSY,
/*
* Pause was called while descriptor was BUSY. Due to hardware
* limitations, only termination is possible for descriptors
* that have been paused.
*/
PAUSED,
/* /*
* Sitting on the channel work_list but xfer done * Sitting on the channel work_list but xfer done
* by PL330 core * by PL330 core
@ -2041,7 +2047,7 @@ static inline void fill_queue(struct dma_pl330_chan *pch)
list_for_each_entry(desc, &pch->work_list, node) { list_for_each_entry(desc, &pch->work_list, node) {
/* If already submitted */ /* If already submitted */
if (desc->status == BUSY) if (desc->status == BUSY || desc->status == PAUSED)
continue; continue;
ret = pl330_submit_req(pch->thread, desc); ret = pl330_submit_req(pch->thread, desc);
@ -2326,6 +2332,7 @@ static int pl330_pause(struct dma_chan *chan)
{ {
struct dma_pl330_chan *pch = to_pchan(chan); struct dma_pl330_chan *pch = to_pchan(chan);
struct pl330_dmac *pl330 = pch->dmac; struct pl330_dmac *pl330 = pch->dmac;
struct dma_pl330_desc *desc;
unsigned long flags; unsigned long flags;
pm_runtime_get_sync(pl330->ddma.dev); pm_runtime_get_sync(pl330->ddma.dev);
@ -2335,6 +2342,10 @@ static int pl330_pause(struct dma_chan *chan)
_stop(pch->thread); _stop(pch->thread);
spin_unlock(&pl330->lock); spin_unlock(&pl330->lock);
list_for_each_entry(desc, &pch->work_list, node) {
if (desc->status == BUSY)
desc->status = PAUSED;
}
spin_unlock_irqrestore(&pch->lock, flags); spin_unlock_irqrestore(&pch->lock, flags);
pm_runtime_mark_last_busy(pl330->ddma.dev); pm_runtime_mark_last_busy(pl330->ddma.dev);
pm_runtime_put_autosuspend(pl330->ddma.dev); pm_runtime_put_autosuspend(pl330->ddma.dev);
@ -2425,7 +2436,7 @@ pl330_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
else if (running && desc == running) else if (running && desc == running)
transferred = transferred =
pl330_get_current_xferred_count(pch, desc); pl330_get_current_xferred_count(pch, desc);
else if (desc->status == BUSY) else if (desc->status == BUSY || desc->status == PAUSED)
/* /*
* Busy but not running means either just enqueued, * Busy but not running means either just enqueued,
* or finished and not yet marked done * or finished and not yet marked done
@ -2442,6 +2453,9 @@ pl330_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
case DONE: case DONE:
ret = DMA_COMPLETE; ret = DMA_COMPLETE;
break; break;
case PAUSED:
ret = DMA_PAUSED;
break;
case PREP: case PREP:
case BUSY: case BUSY:
ret = DMA_IN_PROGRESS; ret = DMA_IN_PROGRESS;