Re: [PATCH v2 2/4] ALSA: hda: Rework snd_hdac_stream_reset() to use macros

From: Takashi Iwai
Date: Wed Oct 05 2022 - 10:08:01 EST


On Wed, 05 Oct 2022 15:52:01 +0200,
Jon Hunter wrote:
>
>
> On 05/10/2022 13:29, Takashi Iwai wrote:
>
> ...
>
> >> HDA playback is failing on -next for various Tegra boards. Bisect is
> >> point to this commit and reverting it fixes the problem. I was a bit
> >> puzzled why this change is causing a problem, but looking closer there
> >> is a difference between the previous code that was calling
> >> snd_hdac_stream_readb() and the new code that is calling
> >> snd_hdac_stream_readb_poll(). The function snd_hdac_stream_readb()
> >> calls snd_hdac_aligned_mmio() is see if the device has an aligned MMIO
> >> which Tegra does and then would call snd_hdac_aligned_read(). However,
> >> now the code always call readb() and this is breaking Tegra.
> >>
> >> So it is either necessary to update snd_hdac_stream_readb_poll() to
> >> handle this or revert this change.
> >
> > Does the patch below work?
> >
> >
> > thanks,
> >
> > Takashi
> >
> > -- 8< --
> > --- a/include/sound/hdaudio.h
> > +++ b/include/sound/hdaudio.h
> > @@ -592,8 +592,8 @@ int snd_hdac_get_stream_stripe_ctl(struct hdac_bus *bus,
> > #define snd_hdac_stream_readb(dev, reg) \
> > snd_hdac_reg_readb((dev)->bus, (dev)->sd_addr + AZX_REG_ ## reg)
> > #define snd_hdac_stream_readb_poll(dev, reg, val, cond, delay_us, timeout_us) \
> > - readb_poll_timeout((dev)->sd_addr + AZX_REG_ ## reg, val, cond, \
> > - delay_us, timeout_us)
> > + read_poll_timeout(snd_hdac_reg_readb, val, cond, delay_us, timeout_us,\
> > + false, (dev)->bus, (dev)->sd_addr + AZX_REG_ ## reg)
> > #define snd_hdac_stream_readl_poll(dev, reg, val, cond, delay_us, timeout_us) \
> > readl_poll_timeout((dev)->sd_addr + AZX_REG_ ## reg, val, cond, \
> > delay_us, timeout_us)
>
>
> Amazingly it does not work. I would have thought that would, but it
> does not. I am a bit puzzled by that?

Interesting, it must be a subtle difference.
What about passing true? It seems that the original code has the
udelay(3) before the loop.


Takashi

-- 8< --
--- a/include/sound/hdaudio.h
+++ b/include/sound/hdaudio.h
@@ -592,8 +592,8 @@ int snd_hdac_get_stream_stripe_ctl(struct hdac_bus *bus,
#define snd_hdac_stream_readb(dev, reg) \
snd_hdac_reg_readb((dev)->bus, (dev)->sd_addr + AZX_REG_ ## reg)
#define snd_hdac_stream_readb_poll(dev, reg, val, cond, delay_us, timeout_us) \
- readb_poll_timeout((dev)->sd_addr + AZX_REG_ ## reg, val, cond, \
- delay_us, timeout_us)
+ read_poll_timeout(snd_hdac_reg_readb, val, cond, delay_us, timeout_us,\
+ true, (dev)->bus, (dev)->sd_addr + AZX_REG_ ## reg)
#define snd_hdac_stream_readl_poll(dev, reg, val, cond, delay_us, timeout_us) \
readl_poll_timeout((dev)->sd_addr + AZX_REG_ ## reg, val, cond, \
delay_us, timeout_us)