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

Message ID 20190326103146.24795-23-tomi.valkeinen@ti.com
State New
Headers show
Series
  • drm/bridge: tc358767: DP support
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Commit Message

Tomi Valkeinen March 26, 2019, 10:31 a.m.
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.

Suggestions welcome.


 .../devicetree/bindings/display/bridge/toshiba,tc358767.txt    | 3 +++
 1 file changed, 3 insertions(+)

Comments

Rob Herring March 31, 2019, 6:42 a.m. | #1
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
>

Patch

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