linux-kernel - Re: [RESEND PATCH v4 03/21] staging: media: tegra-video: fix .vidioc_enum_fmt_vid

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] [day] [month] [year] [list]

Message-ID: <20230405143018.GC9915@pendragon.ideasonboard.com>
Date:   Wed, 5 Apr 2023 17:30:18 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Hans Verkuil <hverkuil-cisco@...all.nl>
Cc:     Luca Ceresoli <luca.ceresoli@...tlin.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Sowjanya Komatineni <skomatineni@...dia.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dmitry Osipenko <digetx@...il.com>,
        linux-media@...r.kernel.org, linux-tegra@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-staging@...ts.linux.dev,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        Richard Leitner <richard.leitner@...data.com>
Subject: Re: [RESEND PATCH v4 03/21] staging: media: tegra-video: fix
 .vidioc_enum_fmt_vid_cap to return all formats

Hi Hans,

On Wed, Apr 05, 2023 at 10:50:37AM +0200, Hans Verkuil wrote:
> On 05/04/2023 10:31, Luca Ceresoli wrote:
> > On Wed, 5 Apr 2023 05:30:48 +0300 Laurent Pinchart wrote:
> >> On Tue, Apr 04, 2023 at 04:12:51PM +0200, Luca Ceresoli wrote:
> >>> On Wed, 29 Mar 2023 13:16:22 +0200 Hans Verkuil wrote:
> >>>   
> >>>> Hi Luca,
> >>>>
> >>>> I finally found the time to test this series. It looks OK, except for this patch.  
> >>>
> >>> Thank you very much for taking the time!
> >>>   
> >>>> The list of supported formats really has to be the intersection of what the tegra
> >>>> supports and what the sensor supports.
> >>>>
> >>>> Otherwise you would advertise pixelformats that cannot be used, and the application
> >>>> would have no way of knowing that.  
> >>>
> >>> As far as I understand, I think we should rather make this driver fully
> >>> behave as an MC-centric device. It is already using MC quite
> >>> successfully after all.
> >>>
> >>> Do you think this is correct?  
> >>
> >> Given the use cases for this driver, I agree.
> 
> I disagree.
> 
> This driver doesn't use the media controller for anything at the moment. The
> /dev/mediaX device just shows the internal topology (i.e. connected sensors),
> but otherwise it does nothing.
> 
> While it would be great if we could unlock the ISP on the Tegra, the reality
> is that it is entirely closed source and can't be used in a linux driver, and
> that's not going to change, sadly.

Never say never :-)

> That leaves us with just a basic CSI capture driver. Rather than trying to
> change this driver to a full MC device with no benefits, just drop this change
> and get your code in.

Can't the hardware support capturing different virtual channels or data
types from the same CSI-2 source ? That would require MC support, the
stream API requires subdev device nodes.

> Note that this driver will stay in staging since it still fails when I try to
> capture from two sensors at the same time: syncpoint errors start appearing
> in that case. I think there are locking issues. I think I have someone to take
> a look at that, but first I want your series to get merged.
> 
> In the very unlikely event that the ISP can be implemented in a linux driver,
> it will probably become a new driver.
> 
> Regards,
> 
> > Ok, thanks for the feedback. I will send a v5 with this change.

-- 
Regards,

Laurent Pinchart