linux-kernel - Re: [PATCH v5] ASoC: wm8978: add missing BCLK divider setup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAN7C2SCDNz5TB3deVziuNNYFnPV_hmrsPL1k-j5Dsj58wvC2rw@mail.gmail.com>
Date: Thu, 9 Oct 2025 02:27:19 +0800
From: Sune Brian <briansune@...il.com>
To: Charles Keepax <ckeepax@...nsource.cirrus.com>
Cc: Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, 
	Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>, linux-sound@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] ASoC: wm8978: add missing BCLK divider setup

Charles Keepax <ckeepax@...nsource.cirrus.com> 於 2025年10月9日 週四 上午1:16寫道：

> What you missing here is that your bclk_divs are sorted so all
> this min_diff is wasted effort. Each time you move to a higher
> divider there are only two options:
>
> 1) You are closer to the target bclk than last time.
> 2) You are under the target bclk and the system won't work.
>
> So the last value that gives a bclk above the target is the
> min_diff by definition.
>
> Thanks,
> Charles
>
> [1] https://www.nxp.com/docs/en/user-manual/UM11732.pdf

Document had read and indeed it mentioned it will be ignored.
I apologized on my strong words about IIS standard about extra bit clocks.
However, it just mentioned if there are additional bit happens will be ignored.
It never said this is a way to relay between MCLK LRCLK and BCLK.
As such I am still don't convinced this is a proper way to reach the
targeted S.R.
And my stand of MCLK <-> BCLK <-> LRCLK relationship still holds strong.
No matter how you do it, it will only result in a close result but not
match result.
Doing faster BCLK but unnecessary just make setup/slack timing issues.
Any specifications on how much you can overrun from first place?
Which make zero sense and reason to do so from first place.
If BCLK is slow then the final S.R. is slowed this is what it is.
Same as BCLK is fast then S.R. is fasted as it is.

As for this patch do the current version introduce any error or bug.
If not then I will stop the patching.
Leave it to other to patch the approximated BCLK.

Brian