linux-kernel - Re: [PATCH 1/3] media: qcom: camss: vfe: Stop spamming logs with version

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: <aCw_3cDSCQ09NSKB@hovoldconsulting.com>
Date: Tue, 20 May 2025 10:39:57 +0200
From: Johan Hovold <johan@...nel.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
	Robert Foss <rfoss@...nel.org>, Todor Tomov <todor.too@...il.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	linux-media@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] media: qcom: camss: vfe: Stop spamming logs with
 version

On Tue, May 20, 2025 at 10:30:16AM +0200, Krzysztof Kozlowski wrote:
> On 20/05/2025 10:23, Johan Hovold wrote:
> > On Tue, May 20, 2025 at 10:02:32AM +0200, Krzysztof Kozlowski wrote:
> >> On 20/05/2025 09:53, Johan Hovold wrote:
> > 
> >>> Spamming the logs as the driver currently does is clearly broken and
> >>> should be fixed. Keeping a hw version dev_dbg() is generally perfectly
> >>> fine, though.
> > 
> >> My main argument, expressed in the commit msg to which no one objected,
> >> is that this debug is 100% useless: deducible from the compatible,
> >> always known upfront, always the same.
> > 
> > To me that deduction does not seem straightforward, at least not without
> > access to internal qualcomm docs, for example:
> > 
> > 	compatible = "qcom,sc8280xp-camss";
> > 
> >         qcom-camss ac5a000.camss: VFE:0 HW Version = 1.2.2
> > 	qcom-camss ac5a000.camss: VFE:1 HW Version = 1.2.2
> >         qcom-camss ac5a000.camss: VFE:2 HW Version = 1.2.2
> >         qcom-camss ac5a000.camss: VFE:3 HW Version = 1.2.2
> >         qcom-camss ac5a000.camss: VFE:4 HW Version = 1.3.0
> >         qcom-camss ac5a000.camss: VFE:5 HW Version = 1.3.0
> >         qcom-camss ac5a000.camss: VFE:6 HW Version = 1.3.0
> >         qcom-camss ac5a000.camss: VFE:7 HW Version = 1.3.0
> > 
> 
> I understand that deduction is not straightforward, but it is also a
> fixed one, meaning it will be always sc8280xp -> (vFOO, vBAR), thus the
> only usefulness of above is to map each compatible to pair of two HW
> versions. This can be done via debugfs interface once and stored in
> public docs. No need to do that mapping every time driver probes and my
> patches drop nice chunk of code, including indirect function calls.

If you still want to export it through debugfs at some point, then it
seems there is still some worth in having it.

I'm sure the implementation is terrible, and maybe that's reason enough
to simply drop it in this case. But again, generally it's perfectly fine
to print a hardware revision at debug level (once) during probe.

Johan