linux-kernel - Re: [RFC PATCH v2 0/7] of: Introduce hardware prober driver

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]

Date:   Fri, 10 Nov 2023 16:12:06 -0800
From:   Doug Anderson <dianders@...omium.org>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Chen-Yu Tsai <wenst@...omium.org>,
        Frank Rowand <frowand.list@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        andriy.shevchenko@...ux.intel.com, Jiri Kosina <jikos@...nel.org>,
        linus.walleij@...aro.org, broonie@...nel.org,
        gregkh@...uxfoundation.org, hdegoede@...hat.com,
        james.clark@....com, james@...iv.tech, keescook@...omium.org,
        petr.tesarik.ext@...wei.com, rafael@...nel.org, tglx@...utronix.de,
        Jeff LaBundy <jeff@...undy.com>, linux-input@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Johan Hovold <johan@...nel.org>
Subject: Re: [RFC PATCH v2 0/7] of: Introduce hardware prober driver

Hi,

On Thu, Nov 9, 2023 at 5:52 AM Rob Herring <robh+dt@...nel.org> wrote:
>
> > > End of background from Doug's cover letter.
> >
> > I think that using "status" is not a good idea, I find that confusing.
>
> "status" is what defines a device's state in terms of enabled,
> present, available. That's exactly what we're expressing here.
>
> Now, I do not think we should be mixing the device class (e.g.
> touchscreen) into status. I said this on v1, but apparently that was
> not listened to.

Interesting. I must have missed the "don't mix device class into
status" part. Do you have a link to your post about that? Maybe
there's other stuff I missed... Having the device class stuck at the
end there was at least part of my last post [1] which gathered no
response.

I think one of the reasons that I felt we needed to mux the device
class into status was that it was going to make the code a lot less
fragile. Everything I've seen indicates that you don't want us to
create a "HW prober" node that could be used to provide relevant
phandles for different classes of devices, so the "HW prober" code
needs to either search through the whole device tree for a status of
"failed-needs-probe" or needs to contain per-board, hardcoded,
fully-qualified paths.

I don't think we want to include hardcoded, fully-qualified paths in
the code. That would mean that if someone changed a node name
somewhere in the path to one of the devices that we're dealing with
then it would break.

So if we're searching the whole device tree for "failed-needs-probe"
then we need to figure out which devices are related to each other. If
a given board has second sources for MIPI panels, touchscreens, and
trackpads then we need to know which of the "failed-needs-probe"
devices are trackpads, which are touchscreens, and which are MIPI
panels. Do you have any suggestions for how we should do that? Maybe
it was in some other thread that I missed? I guess we could have a
board-specific table mapping (compatible + node name + reg) to a
class, but that feels awkward.

[1] https://lore.kernel.org/r/CAD=FV=UjVAgT-febtj4=UZ2GQp01D-ern2Ff9+ODcHeQBOsdTQ@mail.gmail.com