Re: [PATCH v2 2/4] drm/msm/hdmi: Clean up HDMI gpio DT bindings

From: Archit Taneja <architt@codeaurora.org>
To: Rob Herring <robh@kernel.org>, robdclark@gmail.com
Cc: andy.gross@linaro.org, linux-arm-msm@vger.kernel.org,
	dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org
Subject: Re: [PATCH v2 2/4] drm/msm/hdmi: Clean up HDMI gpio DT bindings
Date: Tue, 13 Sep 2016 12:42:13 +0530	[thread overview]
Message-ID: <57D7A6CD.60803@codeaurora.org> (raw)
In-Reply-To: <20160912131914.GA15499@rob-hp-laptop>

On 9/12/2016 6:49 PM, Rob Herring wrote:
> On Thu, Sep 01, 2016 at 07:06:52PM +0530, Archit Taneja wrote:
>> Make the following changes in the HDMI gpio bindings:
>>
>> - Use "-gpios" as the suffix for all the gpio names
>> - Move all the gpios to optional, since there are platforms that use none
>>    of them.
>> - The HPD gpio is a standard one, remove the "qcom,hdmi-tx-" prefix from
>>    it.
>> - Add a missing lpm gpio used on some platforms.
>>
>> Make the necessary changes in the driver to incorporate these changes.
>>
>> There hasn't been any upstream DT that uses the HDMI bindings, so it's
>> okay to change and move around these properties.
>>
>> Cc: Rob Herring <robh@kernel.org>
>> Cc: devicetree@vger.kernel.org
>> Signed-off-by: Archit Taneja <architt@codeaurora.org>
>> ---
>> v2:
>> - Keep "qcom,hdmi-tx-" suffix for all gpios except for hpd.
>> - Use "-gpios" suffix instead of "-gpio".
>> - Move all the gpios to optional properties.
>>
>>   .../devicetree/bindings/display/msm/hdmi.txt        | 11 ++++++-----
>>   drivers/gpu/drm/msm/hdmi/hdmi.c                     | 21 +++++++++++++++++++--
>>   2 files changed, 25 insertions(+), 7 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/display/msm/hdmi.txt b/Documentation/devicetree/bindings/display/msm/hdmi.txt
>> index ce84459..f1a83ab 100644
>> --- a/Documentation/devicetree/bindings/display/msm/hdmi.txt
>> +++ b/Documentation/devicetree/bindings/display/msm/hdmi.txt
>> @@ -13,17 +13,18 @@ Required properties:
>>   - interrupts: The interrupt signal from the hdmi block.
>>   - clocks: device clocks
>>     See ../clocks/clock-bindings.txt for details.
>> -- qcom,hdmi-tx-ddc-clk-gpio: ddc clk pin
>> -- qcom,hdmi-tx-ddc-data-gpio: ddc data pin
>> -- qcom,hdmi-tx-hpd-gpio: hpd pin
>>   - core-vdda-supply: phandle to supply regulator
>>   - hdmi-mux-supply: phandle to mux regulator
>>   - phys: the phandle for the HDMI PHY device
>>   - phy-names: the name of the corresponding PHY device
>>
>>   Optional properties:
>> -- qcom,hdmi-tx-mux-en-gpio: hdmi mux enable pin
>> -- qcom,hdmi-tx-mux-sel-gpio: hdmi mux select pin
>> +- qcom,hdmi-tx-ddc-clk-gpios: ddc clk pin
>> +- qcom,hdmi-tx-ddc-data-gpios: ddc data pin
>
> Sorry, for raising another point, but couldn't you use the i2c-gpio
> binding for these instead?

I'm not entirely sure what these are used for either, they predate the
APQ8064 SoC. They are certainly not bit-banged to implement i2c, since
the driver just sets them to a high during driver initialization, and
we have our dedicated i2c controller anyway.

Rob,

Are you aware why we have these for older SoCs?

Thanks,
Archit

>
>> +- hpd-gpios: hpd pin
>> +- qcom,hdmi-tx-mux-en-gpios: hdmi mux enable pin
>> +- qcom,hdmi-tx-mux-sel-gpios: hdmi mux select pin
>> +- qcom,hdmi-tx-mux-lpm-gpios: hdmi mux lpm pin
>>   - power-domains: reference to the power domain(s), if available.
>>   - pinctrl-names: the pin control state names; should contain "default"
>>   - pinctrl-0: the default pinctrl state (active)

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