Hi,
On 08/03/2024 23:00, Sean Anderson wrote:
xilinx_dpdma_chan_done_irq and xilinx_dpdma_chan_vsync_irq are always
called with IRQs disabled from xilinx_dpdma_irq_handler. Therefore we
don't need to save/restore the IRQ flags.
I think this is fine, but a few thoughts:
- Is spin_lock clearly faster than the irqsave variant, or is this a
pointless optimization? It's safer to just use irqsave variant, instead
of making sure the code is always called from the expected contexts.
- Is this style documented/recommended anywhere? Going through docs, I
only found docs telling to use irqsave when mixing irq and non-irq contexts.
- Does this cause issues on PREEMPT_RT?
Tomi
Signed-off-by: Sean Anderson <sean.anderson@xxxxxxxxx>
---
drivers/dma/xilinx/xilinx_dpdma.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/drivers/dma/xilinx/xilinx_dpdma.c b/drivers/dma/xilinx/xilinx_dpdma.c
index eb0637d90342..36bd4825d389 100644
--- a/drivers/dma/xilinx/xilinx_dpdma.c
+++ b/drivers/dma/xilinx/xilinx_dpdma.c
@@ -1043,9 +1043,8 @@ static int xilinx_dpdma_chan_stop(struct xilinx_dpdma_chan *chan)
static void xilinx_dpdma_chan_done_irq(struct xilinx_dpdma_chan *chan)
{
struct xilinx_dpdma_tx_desc *active;
- unsigned long flags;
- spin_lock_irqsave(&chan->lock, flags);
+ spin_lock(&chan->lock);
xilinx_dpdma_debugfs_desc_done_irq(chan);
@@ -1057,7 +1056,7 @@ static void xilinx_dpdma_chan_done_irq(struct xilinx_dpdma_chan *chan)
"chan%u: DONE IRQ with no active descriptor!\n",
chan->id);
- spin_unlock_irqrestore(&chan->lock, flags);
+ spin_unlock(&chan->lock);
}
/**
@@ -1072,10 +1071,9 @@ static void xilinx_dpdma_chan_vsync_irq(struct xilinx_dpdma_chan *chan)
{
struct xilinx_dpdma_tx_desc *pending;
struct xilinx_dpdma_sw_desc *sw_desc;
- unsigned long flags;
u32 desc_id;
- spin_lock_irqsave(&chan->lock, flags);
+ spin_lock(&chan->lock);
pending = chan->desc.pending;
if (!chan->running || !pending)
@@ -1108,7 +1106,7 @@ static void xilinx_dpdma_chan_vsync_irq(struct xilinx_dpdma_chan *chan)
spin_unlock(&chan->vchan.lock);
out:
- spin_unlock_irqrestore(&chan->lock, flags);
+ spin_unlock(&chan->lock);
}
/**
