From mboxrd@z Thu Jan 1 00:00:00 1970 From: Liam Girdwood Subject: Re: [PATCH] ALSA: core: Allow drivers to set R/W wait time. Date: Thu, 15 Mar 2018 13:35:37 +0000 Message-ID: <1521120937.7762.258.camel@linux.intel.com> References: <20180314204440.14027-1-liam.r.girdwood@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by alsa0.perex.cz (Postfix) with ESMTP id 68903267252 for ; Thu, 15 Mar 2018 14:35:41 +0100 (CET) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: Takashi Iwai Cc: alsa-devel@alsa-project.org, Mark Brown List-Id: alsa-devel@alsa-project.org On Wed, 2018-03-14 at 23:04 +0100, Takashi Iwai wrote: > On Wed, 14 Mar 2018 21:44:40 +0100, > Liam Girdwood wrote: > > > > Currently ALSA core blocks userspace for about 10 seconds for PCM R/W IO. > > This needs to be configurable for modern hardware like DSPs where no > > pointer update in milliseconds can indicate terminal DSP errors. > > > > Add a substream variable to set the wait time in ms. This allows userspace > > and drivers to recover more quickly from terminal DSP errors. > > > > Signed-off-by: Liam Girdwood > > The idea looks good, though, a bit of nitpicking: > > > --- > > include/sound/pcm.h | 6 ++++++ > > sound/core/pcm_lib.c | 15 ++++++++++----- > > 2 files changed, 16 insertions(+), 5 deletions(-) > > > > diff --git a/include/sound/pcm.h b/include/sound/pcm.h > > index e054c583d3b3..e4694684c524 100644 > > --- a/include/sound/pcm.h > > +++ b/include/sound/pcm.h > > @@ -462,6 +462,7 @@ struct snd_pcm_substream { > > /* -- timer section -- */ > > struct snd_timer *timer; /* timer */ > > unsigned timer_running: 1; /* time is running */ > > + unsigned wait_time; /* time in ms for R/W to wait for avail > > */ > > I'd name wait_timeout, which is slightly clearer. > > > > /* -- next substream -- */ > > struct snd_pcm_substream *next; > > /* -- linked substreams -- */ > > @@ -579,6 +580,11 @@ int snd_pcm_start(struct snd_pcm_substream *substream); > > int snd_pcm_stop(struct snd_pcm_substream *substream, snd_pcm_state_t > > status); > > int snd_pcm_drain_done(struct snd_pcm_substream *substream); > > int snd_pcm_stop_xrun(struct snd_pcm_substream *substream); > > +static inline void snd_pcm_wait_time(struct snd_pcm_substream *substream, > > + unsigned wait_time) > > +{ > > + substream->wait_time = wait_time; > > +} > > IMO, it's a simple one parameter, and no need wrapping with an inline > function. This was for drivers to set the parameter according to HW capabilities. > > > > > #ifdef CONFIG_PM > > int snd_pcm_suspend(struct snd_pcm_substream *substream); > > int snd_pcm_suspend_all(struct snd_pcm *pcm); > > diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c > > index a83152e7d387..2ee76c70f55f 100644 > > --- a/sound/core/pcm_lib.c > > +++ b/sound/core/pcm_lib.c > > @@ -1839,12 +1839,17 @@ static int wait_for_avail(struct snd_pcm_substream > > *substream, > > if (runtime->no_period_wakeup) > > wait_time = MAX_SCHEDULE_TIMEOUT; > > else { > > - wait_time = 10; > > - if (runtime->rate) { > > - long t = runtime->period_size * 2 / runtime->rate; > > - wait_time = max(t, wait_time); > > + /* use wait time from substream if available */ > > + if (substream->wait_time) { > > + wait_time = msecs_to_jiffies(substream->wait_time); > > + } else { > > + wait_time = 10; > > + if (runtime->rate) { > > + long t = runtime->period_size * 2 / > > runtime->rate; > > + wait_time = max(t, wait_time); > > + } > > + wait_time = msecs_to_jiffies(wait_time * 1000); > > } > > - wait_time = msecs_to_jiffies(wait_time * 1000); > > This can go bad when wait_time is shorter than the period time. > Some validation is needed? > Yes, and we should also validate no irq mode somehow too, probably using buffer time. > Also, how is user-space supposed to set the new parameter? > It's not atm, as it was being set by the driver. Would probably mean an ABI change to PCM ops or a new ioctl ? The latter wont break the ABI and the default value would remain if the ioctl was not called. Liam > > thanks, > > Takashi