This is a note to let you know that I've just added the patch titled
ASoC: meson: axg-fifo: fix irq scheduling issue with PREEMPT_RT
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
asoc-meson-axg-fifo-fix-irq-scheduling-issue-with-pr.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 65cc8a10ec933b168fbb0a632d67261a6d38c05e
Author: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
Date: Wed Aug 7 18:27:03 2024 +0200
ASoC: meson: axg-fifo: fix irq scheduling issue with PREEMPT_RT
[ Upstream commit 5003d0ce5c7da3a02c0aff771f516f99731e7390 ]
With PREEMPT_RT enabled a spinlock_t becomes a sleeping lock.
This is usually not a problem with spinlocks used in IRQ context since
IRQ handlers get threaded. However, if IRQF_ONESHOT is set, the primary
handler won't be force-threaded and runs always in hardirq context. This is
a problem because spinlock_t requires a preemptible context on PREEMPT_RT.
In this particular instance, regmap mmio uses spinlock_t to protect the
register access and IRQF_ONESHOT is set on the IRQ. In this case, it is
actually better to do everything in threaded handler and it solves the
problem with PREEMPT_RT.
Reported-by: Arseniy Krasnov <avkrasnov@xxxxxxxxxxxxxxxxx>
Closes: https://lore.kernel.org/linux-amlogic/20240729131652.3012327-1-avkrasnov@xxxxxxxxxxxxxxxxx
Suggested-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Fixes: b11d26660dff ("ASoC: meson: axg-fifo: use threaded irq to check periods")
Signed-off-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Link: https://patch.msgid.link/20240807162705.4024136-1-jbrunet@xxxxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/sound/soc/meson/axg-fifo.c b/sound/soc/meson/axg-fifo.c
index 94b169a5493b5..5218e40aeb1bb 100644
--- a/sound/soc/meson/axg-fifo.c
+++ b/sound/soc/meson/axg-fifo.c
@@ -207,25 +207,18 @@ static irqreturn_t axg_fifo_pcm_irq_block(int irq, void *dev_id)
status = FIELD_GET(STATUS1_INT_STS, status);
axg_fifo_ack_irq(fifo, status);
- /* Use the thread to call period elapsed on nonatomic links */
- if (status & FIFO_INT_COUNT_REPEAT)
- return IRQ_WAKE_THREAD;
+ if (status & ~FIFO_INT_COUNT_REPEAT)
+ dev_dbg(axg_fifo_dev(ss), "unexpected irq - STS 0x%02x\n",
+ status);
- dev_dbg(axg_fifo_dev(ss), "unexpected irq - STS 0x%02x\n",
- status);
+ if (status & FIFO_INT_COUNT_REPEAT) {
+ snd_pcm_period_elapsed(ss);
+ return IRQ_HANDLED;
+ }
return IRQ_NONE;
}
-static irqreturn_t axg_fifo_pcm_irq_block_thread(int irq, void *dev_id)
-{
- struct snd_pcm_substream *ss = dev_id;
-
- snd_pcm_period_elapsed(ss);
-
- return IRQ_HANDLED;
-}
-
int axg_fifo_pcm_open(struct snd_soc_component *component,
struct snd_pcm_substream *ss)
{
@@ -251,8 +244,9 @@ int axg_fifo_pcm_open(struct snd_soc_component *component,
if (ret)
return ret;
- ret = request_threaded_irq(fifo->irq, axg_fifo_pcm_irq_block,
- axg_fifo_pcm_irq_block_thread,
+ /* Use the threaded irq handler only with non-atomic links */
+ ret = request_threaded_irq(fifo->irq, NULL,
+ axg_fifo_pcm_irq_block,
IRQF_ONESHOT, dev_name(dev), ss);
if (ret)
return ret;
