linux-kernel - Re: [PATCH v2 2/4] ALSA: hda: Rework snd_hdac_stream

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Date:   Wed, 05 Oct 2022 16:07:54 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Jon Hunter <jonathanh@...dia.com>
Cc:     Amadeusz Sławiński 
        <amadeuszx.slawinski@...ux.intel.com>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org,
        Cezary Rojewski <cezary.rojewski@...el.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        Mohan Kumar D <mkumard@...dia.com>
Subject: Re: [PATCH v2 2/4] ALSA: hda: Rework snd_hdac_stream_reset() to use macros

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)