From: "Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Conor Dooley <conor+dt@kernel.org>,
Geert Uytterhoeven <geert+renesas@glider.be>,
linux-media@vger.kernel.org, devicetree@vger.kernel.org,
linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH] dt-bindings: media: renesas,isp: Add binding for V4M
Date: Tue, 4 Jun 2024 11:18:59 +0200 [thread overview]
Message-ID: <20240604091859.GD710180@ragnatech.se> (raw)
In-Reply-To: <CAMuHMdWRwRq-CzT5v1h6W31q_0RR4UvTpJAVVS73vrEbrxFmBg@mail.gmail.com>
Hi Geert,
Thanks for your review.
On 2024-06-04 09:38:04 +0200, Geert Uytterhoeven wrote:
> Hi Niklas,
>
> On Mon, May 27, 2024 at 3:20 PM Niklas Söderlund
> <niklas.soderlund+renesas@ragnatech.se> wrote:
> > Document support for the ISP module in the Renesas V4M (r8a779h0) SoC.
> >
> > Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
>
> Thanks for your patch!
>
> > --- a/Documentation/devicetree/bindings/media/renesas,isp.yaml
> > +++ b/Documentation/devicetree/bindings/media/renesas,isp.yaml
> > @@ -22,6 +22,7 @@ properties:
> > - enum:
> > - renesas,r8a779a0-isp # V3U
> > - renesas,r8a779g0-isp # V4H
> > + - renesas,r8a779h0-isp # V4M
> > reg:
> > maxItems: 1
>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
>
> BTW, this binding only describes a single register block, while the
> ISP seems to have two: CS and CORE (the second one is optional, as it
> does not exist for the second instance of R-Car V4M)?
Yes. The R-Car ISP have two different functions, CSI-2 Channel Selection
(CS) and a more traditional ISP block to do cool stuff to image data
(core). We only have documentation for the CS, and only that which is
needed to setup CSI-2 reception and forward data to a capture engine
(VIN), so this is all the rcar-isp driver deals with.
For the interested, difference between generations,
On Gen3 the capture pipeline is $source -> rcar-csi2 -> rcar-vin. The
CSI-2 channel selection is done from registers on the VIN master
instances but effect other VIN instances, this is one reason the
rcar-vin driver is so ugly as each VIN instance is not self contained.
While the CSI-2 VC/DT filtering is done in the rcar-csi2 driver.
On Gen4 the capture pipeline is $source -> rcar-csi2 -> rcar-isp ->
rcar-vin. And both the channel selection and VC/DT filtering is done in
the rcar-isp. IMHO this is slightly better design then on Gen3 but
created yet another ugliness in the pipeline as now Gen{1,2}, Gen3 and
Gen4 are all supported by the same set of drivers but the same function
is served by different IP blocks depending on which generation, this
makes for somewhat ugly driver code.
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
--
Kind Regards,
Niklas Söderlund
prev parent reply other threads:[~2024-06-04 9:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-27 13:19 [PATCH] dt-bindings: media: renesas,isp: Add binding for V4M Niklas Söderlund
2024-05-27 16:36 ` Conor Dooley
2024-05-27 17:54 ` Niklas Söderlund
2024-05-27 18:07 ` Conor Dooley
2024-06-04 7:38 ` Geert Uytterhoeven
2024-06-04 9:18 ` Niklas Söderlund [this message]
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