Re: [PATCH v2 3/6] dt-bindings: soc: Add a binding for the Broadcom VCHIQ services.

[Rob Herring]

On Wed, Mar 7, 2018 at 12:57 PM, Eric Anholt <eric@xxxxxxxxxx> wrote:
> The VCHIQ communication channel can be provided by BCM283x and Capri
> SoCs, to communicate with the VPU-side OS services.
>
> Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
> ---
>
> v2: dropped firmware property, added cache-line-size.
>
>  .../bindings/soc/bcm/brcm,bcm2835-vchiq.txt        | 28 ++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-vchiq.txt
>
> diff --git a/Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-vchiq.txt b/Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-vchiq.txt
> new file mode 100644
> index 000000000000..cdef4abc5e47
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/soc/bcm/brcm,bcm2835-vchiq.txt
> @@ -0,0 +1,28 @@
> +Broadcom VCHIQ firmware services
> +
> +Required properties:
> +
> +- compatible:  Should be "brcm,bcm2835-vchiq"
> +- reg:         Physical base address and length of the doorbell register pair
> +- interrupts:  The interrupt number
> +                 See bindings/interrupt-controller/brcm,bcm2835-armctrl-ic.txt
> +
> +Optional properties:
> +
> +- cache-line-size:
> +               Size of L2 cache lines.  The VPU firmware detects
> +                 this property and overrides it with the actual L2
> +                 cache line size it's using when loading the
> +                 device-tree.  Determines the required alignment of
> +                 offsets/sizes of VCHIQ pagelists.  If missing, the
> +                 firmware assumes an older kernel using 32-byte
> +                 alignment.

How is this a VCHIQ property? This is a standard property for cache
nodes, but this is not a cache node.

Is it really a problem to just use a fixed maximum alignment? That
seems to be good enough for all the rest of the kernel.

> +
> +Example:
> +
> +vchiq@7e00b840 {

mailbox@...

> +       compatible = "brcm,bcm2835-vchiq";
> +       reg = <0x7e00b840 0xf>;
> +       interrupts = <0 2>;
> +       cache-line-size: <32>;
> +};
> --
> 2.16.2
>