linux-kernel - Re: [PATCH v2 3/3] media: dt-bindings: vpif: new optional property

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Date:   Tue, 28 Feb 2017 12:00:02 +0100
From:   Bartosz Golaszewski <bgolaszewski@...libre.com>
To:     Sekhar Nori <nsekhar@...com>
Cc:     Rob Herring <robh@...nel.org>,
        David Lechner <david@...hnology.com>,
        Kevin Hilman <khilman@...libre.com>,
        Michael Turquette <mturquette@...libre.com>,
        Patrick Titiano <ptitiano@...libre.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mark Rutland <mark.rutland@....com>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-devicetree <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] media: dt-bindings: vpif: new optional property

2017-02-28 6:36 GMT+01:00 Sekhar Nori <nsekhar@...com>:
> On Tuesday 28 February 2017 04:22 AM, Rob Herring wrote:
>> On Wed, Feb 22, 2017 at 02:43:47PM +0100, Bartosz Golaszewski wrote:
>>> Add an optional property - enable-gpios - which can be used to specify
>>> the GPIOs that must be requested to select the vpif functionality.
>>>
>>> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
>>> ---
>>>  Documentation/devicetree/bindings/media/ti,da850-vpif.txt | 7 +++++++
>>>  1 file changed, 7 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/media/ti,da850-vpif.txt b/Documentation/devicetree/bindings/media/ti,da850-vpif.txt
>>> index df7182a..23c5405 100644
>>> --- a/Documentation/devicetree/bindings/media/ti,da850-vpif.txt
>>> +++ b/Documentation/devicetree/bindings/media/ti,da850-vpif.txt
>>> @@ -13,6 +13,9 @@ Required properties:
>>>  - reg: physical base address and length of the registers set for the device;
>>>  - interrupts: should contain IRQ line for the VPIF
>>>
>>> +Optional properties:
>>> +- enable-gpios: phandle of the GPIOs used to select the vpif functionality
>>
>> What does this control exactly? The GPIOs belong in the node they are
>> connected to and having GPIOs routed to this block seems strange.
>
> The DA850 EVM board implements on-board muxing which lets the video
> input (via VPIF) to be routed to a TVP5147 (video decoder) for composite
> input or to a camera header. There are other mux options which use the
> same VPIF SoC pins (RMII ethernet or character LCD).
>
> There is a three-to-eight demux on the board which drives enable signals
> to buffers letting you choose from these options.
>
> From your response, it looks like you want the enable-gpios property to
> be in the TVP5147 or camera node. That does make sense to me.
>

Wouldn't that cause races again? The TVP5147 ADC is probed from within
the vpif driver as a media subdev (after initialize_vpif(),
v4l2_device_register(), irq requests etc.).

Thanks,
Bartosz