From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: andy.gross@linaro.org, david.brown@linaro.org,
linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org,
linux-kernel@vger.kernel.org, bgoswami@codeaurora.org,
rohitkr@codeaurora.org
Subject: Re: [PATCH] qcom: apr: Make apr callbacks in non-atomic context
Date: Thu, 31 Jan 2019 08:05:51 -0800 [thread overview]
Message-ID: <20190131160551.GD2387@tuxbook-pro> (raw)
In-Reply-To: <7555094b-350b-b4c6-47c6-507f7ce99dc5@linaro.org>
On Thu 31 Jan 02:44 PST 2019, Srinivas Kandagatla wrote:
>
>
> On 31/01/2019 01:16, Bjorn Andersson wrote:
> > On Thu 15 Nov 10:49 PST 2018, Srinivas Kandagatla wrote:
> >
> > > APR communication with DSP is not atomic in nature.
> > > Its request-response type. Trying to pretend that these are atomic
> > > and invoking apr client callbacks directly under atomic/irq context has
> > > endless issues with soundcard. It makes more sense to convert these
> > > to nonatomic calls. This also coverts all the dais to be nonatomic.
> > >
> > Hi Srinivas,
> >
> > Sorry for not looking at this before.
> >
> NP, thanks for the review!
>
> > Are you sure that you're meeting the latency requirements of low-latency
> > audio with this change?
>
> Low and Ultra Low Latency audio is not supported in the exiting upstream
> qdsp drivers.
>
Sure, but we want the design to allow for that still, either in future
upstream or by additional downstream code.
> Also it depends on definition of "latency", is the latency referring to
> "filling the data" or "latency between DSP command and response".
>
I'm referring to the latency between the message from the DSP until we
give it a new buffer.
> For former case as long as we have more samples in our ring buffer there
> should be no latency in filling the data.
> For later case it should not really matter as long as former case is taken
> care off.
>
> Low latency audio involves smaller sample sizes and no or minimal
> preprocessing in DSP so am guessing that we should be okay with responses in
> workqueue as long as we have good size ring buffer.
>
Relying on more buffered data will increase the latency of the audio,
preventing you from doing really low-latency things.
Regards,
Bjorn
next prev parent reply other threads:[~2019-01-31 16:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-15 18:49 [PATCH] qcom: apr: Make apr callbacks in non-atomic context Srinivas Kandagatla
2019-01-29 10:51 ` Srinivas Kandagatla
2019-01-31 1:16 ` Bjorn Andersson
2019-01-31 10:44 ` Srinivas Kandagatla
2019-01-31 16:05 ` Bjorn Andersson [this message]
2019-01-31 17:33 ` Srinivas Kandagatla
2019-02-05 18:35 ` Bjorn Andersson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190131160551.GD2387@tuxbook-pro \
--to=bjorn.andersson@linaro.org \
--cc=andy.gross@linaro.org \
--cc=bgoswami@codeaurora.org \
--cc=david.brown@linaro.org \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-soc@vger.kernel.org \
--cc=rohitkr@codeaurora.org \
--cc=srinivas.kandagatla@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.