Re: [PATCHv2 22/22] dt-bindings: tc358767: add IRQ & HPD support

From: Rob Herring <robh@kernel.org>
To: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: devicetree@vger.kernel.org,
	Andrey Smirnov <andrew.smirnov@gmail.com>,
	Andrey Gusakov <andrey.gusakov@cogentembedded.com>,
	Jyri Sarha <jsarha@ti.com>,
	dri-devel@lists.freedesktop.org,
	Peter Ujfalusi <peter.ujfalusi@ti.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCHv2 22/22] dt-bindings: tc358767: add IRQ & HPD support
Date: Sun, 31 Mar 2019 01:42:07 -0500	[thread overview]
Message-ID: <5ca06140.1c69fb81.ff9a3.8660@mx.google.com> (raw)
In-Reply-To: <20190326103146.24795-23-tomi.valkeinen@ti.com>

On Tue, Mar 26, 2019 at 12:31:46PM +0200, Tomi Valkeinen wrote:
> Add DT properties needed for IRQ and HPD support.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Cc: devicetree@vger.kernel.org
> Cc: Rob Herring <robh@kernel.org>
> ---
> 
> A quick summary of tc358767's HPD/GPIO support:
> 
> tc358767 has two pins that can be used as GPIOs. Those can be used for
> HPD by configuring the pin as input. tc358767 supports HW detection of a
> "short" HPD pulse (programmable length) which can be used to detect
> DisplayPort IRQ from the monitor. Afaik, this kind of short pulse
> detection is not possible with common GPIOs found in SoCs.
> 
> While I think the HPD support works ok, I'm unsure about the DT binding.
> I first tried implementing the HPD as a gpiochip, but for interrupts I
> then needed irqchip, and the amount of code started to increase a lot.
> 
> I decided that gpiochip + irqchip just isn't worth the effort and
> complexity here, as most likely the pins will ever be used for HPD.
> 
> So, here I have a simple 'hpd-num' DT property to mark which (if any) of
> the two GPIO pins is used for HPD.

There's similar properties for other chips where some signal has a 
selectable pin assignment.

> 
> Suggestions welcome.
> 
> 
>  .../devicetree/bindings/display/bridge/toshiba,tc358767.txt    | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.txt b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.txt
> index e3f6aa6a214d..79c71e7eb71f 100644
> --- a/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.txt
> +++ b/Documentation/devicetree/bindings/display/bridge/toshiba,tc358767.txt
> @@ -12,6 +12,9 @@ Optional properties:
>                     (active high shutdown input)
>   - reset-gpios: OF device-tree gpio specification for RSTX pin
>                  (active low system reset)
> + - interrupt-parent: phandle of the parent interrupt controller

Drop this, it is implied or in the parent.

> + - interrupts: interrupt specifier for the bridge's interrupt
> + - hpd-num: TC358767 GPIO pin number to which HPD is connected to (0 or 1)

ti,hpd-pin

>   - ports: the ports node can contain video interface port nodes to connect
>     to a DPI/DSI source and to an eDP/DP sink according to [1][2]:
>      - port@0: DSI input port
> -- 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
> 

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