linux-kernel - Re: [PATCH v2 06/16] dt-bindings: timer: add Canaan k210 to Synopsys DesignWare timer

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Message-ID: <ed893417-2c5e-c019-04c6-c7c7ee138ef1@conchuod.ie>
Date:   Mon, 27 Jun 2022 22:18:07 +0100
From:   Conor Dooley <mail@...chuod.ie>
To:     Serge Semin <fancer.lancer@...il.com>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        Vinod Koul <vkoul@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Palmer Dabbelt <palmer@...osinc.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Niklas Cassel <niklas.cassel@....com>,
        Dillon Min <dillon.minfei@...il.com>,
        Heng Sia <jee.heng.sia@...el.com>,
        Jose Abreu <joabreu@...opsys.com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org,
        alsa-devel@...a-project.org, linux-spi@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v2 06/16] dt-bindings: timer: add Canaan k210 to Synopsys
 DesignWare timer

On 27/06/2022 22:13, Serge Semin wrote:
> On Mon, Jun 27, 2022 at 08:39:54PM +0100, Conor Dooley wrote:
>> From: Conor Dooley <conor.dooley@...rochip.com>
>>
>> The Canaan k210 apparently has a Sysnopsys Designware timer but
>> according to the documentation & devicetree it has 2 interrupts rather
>> than the standard one. Add a custom compatible that supports the 2
>> interrupt configuration and falls back to the standard binding (which
>> is currently the one in use in the devicetree entry).
>>
> 
>> Link: https://canaan-creative.com/wp-content/uploads/2020/03/kendryte_standalone_programming_guide_20190311144158_en.pdf #Page 58
> 
> Firstly, it's page 51 in the framework of the document pages
> enumeration.

Ah yes, sorry about that.

> 
> Judging by the comment in the document above and what the HW reference
> manual says regarding the IRQ signals, what you really have on K210 is
> the DW APB Timer IP-cores each configured with two embedded timers.
> It's done by the IP-core synthesize parameter NUM_TIMERS={1..8}, which
> in your case equals to 2. A similar situation is on our SoC and, for
> instance, here:
> 
> arch/arm/boot/dts/berlin2q.dtsi
> arch/arm/boot/dts/berlin2.dtsi
> arch/arm/boot/dts/berlin2cd.dtsi
> (Though the Berlin2 APB Timer have been configured with 8 timers.)
> 
> So the correct modification would be:
> 1. Split up the nodes into two ones with one IRQ per each node.
> 2. Make sure I was right by testing the new dts out.
> 3. Update the DT-node only and leave the DT-bindings as is.

Hmm, sounds good. Will give that a whirl tomorrow.
Thanks for the info/suggestions Sergey.