Accordingly to the documentation the CH_DRAIN bit enforses single bursts when
channel is going to be suspended. This, in case when channel will be resumed,
makes data to flow in non-optimal mode until DMA returns to full burst mode.
The fix differentiates pause / resume cycle from pause / terminate and sets
CH_DRAIN bit accordingly.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
drivers/dma/idma64.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/dma/idma64.c b/drivers/dma/idma64.c
index c7da43c..7d56b47 100644
--- a/drivers/dma/idma64.c
+++ b/drivers/dma/idma64.c
@@ -65,9 +65,6 @@ static void idma64_chan_init(struct idma64 *idma64, struct idma64_chan *idma64c)
u32 cfghi = IDMA64C_CFGH_SRC_PER(1) | IDMA64C_CFGH_DST_PER(0);
u32 cfglo = 0;
- /* Enforce FIFO drain when channel is suspended */
- cfglo |= IDMA64C_CFGL_CH_DRAIN;
-
/* Set default burst alignment */
cfglo |= IDMA64C_CFGL_DST_BURST_ALIGN | IDMA64C_CFGL_SRC_BURST_ALIGN;
@@ -428,12 +425,17 @@ static int idma64_slave_config(struct dma_chan *chan,
return 0;
}
-static void idma64_chan_deactivate(struct idma64_chan *idma64c)
+static void idma64_chan_deactivate(struct idma64_chan *idma64c, bool drain)
{
unsigned short count = 100;
u32 cfglo;
cfglo = channel_readl(idma64c, CFG_LO);
+ if (drain)
+ cfglo |= IDMA64C_CFGL_CH_DRAIN;
+ else
+ cfglo &= ~IDMA64C_CFGL_CH_DRAIN;
+
channel_writel(idma64c, CFG_LO, cfglo | IDMA64C_CFGL_CH_SUSP);
do {
udelay(1);
@@ -456,7 +458,7 @@ static int idma64_pause(struct dma_chan *chan)
spin_lock_irqsave(&idma64c->vchan.lock, flags);
if (idma64c->desc && idma64c->desc->status == DMA_IN_PROGRESS) {
- idma64_chan_deactivate(idma64c);
+ idma64_chan_deactivate(idma64c, false);
idma64c->desc->status = DMA_PAUSED;
}
spin_unlock_irqrestore(&idma64c->vchan.lock, flags);
@@ -486,7 +488,7 @@ static int idma64_terminate_all(struct dma_chan *chan)
LIST_HEAD(head);
spin_lock_irqsave(&idma64c->vchan.lock, flags);
- idma64_chan_deactivate(idma64c);
+ idma64_chan_deactivate(idma64c, true);
idma64_stop_transfer(idma64c);
if (idma64c->desc) {
idma64_vdesc_free(&idma64c->desc->vdesc);
--
2.5.1
--
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