linux-kernel - Re: [PATCH v6 1/9] dt-bindings: dma: dw: Convert DW DMAC to DT binding

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Message-ID: <CAHp75Vd+3ZN51geXg+KiQYVpBZN7F+kgt-2Snw7VDiKiYVqX=A@mail.gmail.com>
Date:   Thu, 18 Jun 2020 11:21:53 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc:     Vinod Koul <vkoul@...nel.org>, Viresh Kumar <vireshk@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Serge Semin <fancer.lancer@...il.com>,
        Rob Herring <robh@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Arnd Bergmann <arnd@...db.de>, linux-mips@...r.kernel.org,
        dmaengine <dmaengine@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 1/9] dt-bindings: dma: dw: Convert DW DMAC to DT binding

On Thu, Jun 18, 2020 at 2:43 AM Serge Semin
<Sergey.Semin@...kalelectronics.ru> wrote:
>
> Modern device tree bindings are supposed to be created as YAML-files
> in accordance with dt-schema. This commit replaces the Synopsis
> Designware DMA controller legacy bare text bindings with YAML file.
> The only required prorties are "compatible", "reg", "#dma-cells" and
> "interrupts", which will be used by the driver to correctly find the
> controller memory region and handle its events. The rest of the properties
> are optional, since in case if either "dma-channels" or "dma-masters" isn't
> specified, the driver will attempt to auto-detect the IP core
> configuration.
>
> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> Reviewed-by: Rob Herring <robh@...nel.org>
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
> Cc: Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>
> Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Cc: linux-mips@...r.kernel.org


Rob, here are questions to you.

> +  dma-channels:
> +    description: |
> +      Number of DMA channels supported by the controller. In case if
> +      not specified the driver will try to auto-detect this and
> +      the rest of the optional parameters.
> +    minimum: 1
> +    maximum: 8

...

> +  multi-block:

> +      maxItems: 8

This maximum is defined by above dma-channels property. Is there any
way to put it in the schema?

...

> +  snps,dma-protection-control:
> +    $ref: /schemas/types.yaml#definitions/uint32
> +    description: |
> +      Bits one-to-one passed to the AHB HPROT[3:1] bus. Each bit setting
> +      indicates the following features: bit 0 - privileged mode,
> +      bit 1 - DMA is bufferable, bit 2 - DMA is cacheable.
> +    default: 0
> +    minimum: 0
> +    maximum: 7

AFAIR this is defined by bit flags, does schema have a mechanism to
define flags-like entries?

-- 
With Best Regards,
Andy Shevchenko