Re: [RFC PATCH] arm64: dts: qcom: add device tree for DB845c working in dual DSI mode

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

18 января 2023 г. 19:32:42 GMT+02:00, Bjorn Andersson <andersson@kernel.org> пишет:
>On Wed, Jan 18, 2023 at 10:20:48AM +0200, Dmitry Baryshkov wrote:
>> While we are testing the DB845c working in dual DSI mode (which is
>> required for the 4k support), create a separate device tree using this
>> configuration.
>> 
>
>I don't think it's right to change the DTB on your device depending on
>your TV's ability to do 4k or not...
>
>I ran into this problem when playing around with 4k-support on the RB3
>as well a while back. I was not able to figure out a way to run the
>lt9611 off two inputs for the lower resolutions and ended never posted
>anything because I couldn't come up with any good solution.


This is implemented with the latest lt9611 patchset, referenced in the patch annotation.

I posted this as an RFC with the separate dts to let people test dual DSI, DPU wide planes, etc. and to compare that with plain old single link DSI/lt9611. 

>
>
>Would it be possible somehow to describe the two ports in DT, but have
>the display driver use one or both depending on the number of inputs
>needed by the lt9611?

This would be very problemsome. Even switching the number of lanes goes against the standard and is not supported by Linux kernel. Supporting switching the host off and on would be a real troublle.

Hopefully, this is is not necessary.

>
>Regards,
>Bjorn
>
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>> ---
>> 
>> Dependencies to be able to verify the 4k@30 mode:
>> [1] https://lore.kernel.org/linux-arm-msm/20221229191856.3508092-1-dmitry.baryshkov@linaro.org/
>> [2] https://lore.kernel.org/dri-devel/20230118081658.2198520-1-dmitry.baryshkov@linaro.org/
>> 
>> ---
>>  arch/arm64/boot/dts/qcom/Makefile             |  1 +
>>  .../boot/dts/qcom/sdm845-db845c-dual-dsi.dts  | 48 +++++++++++++++++++
>>  2 files changed, 49 insertions(+)
>>  create mode 100644 arch/arm64/boot/dts/qcom/sdm845-db845c-dual-dsi.dts
>> 
>> diff --git a/arch/arm64/boot/dts/qcom/Makefile b/arch/arm64/boot/dts/qcom/Makefile
>> index 3e79496292e7..dc55c3b989a4 100644
>> --- a/arch/arm64/boot/dts/qcom/Makefile
>> +++ b/arch/arm64/boot/dts/qcom/Makefile
>> @@ -139,6 +139,7 @@ dtb-$(CONFIG_ARCH_QCOM)	+= sdm845-cheza-r1.dtb
>>  dtb-$(CONFIG_ARCH_QCOM)	+= sdm845-cheza-r2.dtb
>>  dtb-$(CONFIG_ARCH_QCOM)	+= sdm845-cheza-r3.dtb
>>  dtb-$(CONFIG_ARCH_QCOM)	+= sdm845-db845c.dtb
>> +dtb-$(CONFIG_ARCH_QCOM)	+= sdm845-db845c-dual-dsi.dtb
>>  dtb-$(CONFIG_ARCH_QCOM)	+= sdm845-db845c-navigation-mezzanine.dtb
>>  dtb-$(CONFIG_ARCH_QCOM)	+= sdm845-lg-judyln.dtb
>>  dtb-$(CONFIG_ARCH_QCOM)	+= sdm845-lg-judyp.dtb
>> diff --git a/arch/arm64/boot/dts/qcom/sdm845-db845c-dual-dsi.dts b/arch/arm64/boot/dts/qcom/sdm845-db845c-dual-dsi.dts
>> new file mode 100644
>> index 000000000000..4a366dedc841
>> --- /dev/null
>> +++ b/arch/arm64/boot/dts/qcom/sdm845-db845c-dual-dsi.dts
>> @@ -0,0 +1,48 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) 2023, Linaro Ltd.
>> + */
>> +
>> +#include "sdm845-db845c.dts"
>> +
>> +&dsi0 {
>> +	qcom,dual-dsi-mode;
>> +	qcom,master-dsi;
>> +};
>> +
>> +&dsi1 {
>> +	vdda-supply = <&vreg_l26a_1p2>;
>> +
>> +	qcom,dual-dsi-mode;
>> +
>> +	/* DSI1 is slave, so use DSI0 clocks */
>> +	assigned-clock-parents = <&dsi0_phy 0>, <&dsi0_phy 1>;
>> +
>> +	status = "okay";
>> +
>> +	ports {
>> +		port@1 {
>> +			endpoint {
>> +				remote-endpoint = <&lt9611_b>;
>> +				data-lanes = <0 1 2 3>;
>> +			};
>> +		};
>> +	};
>> +};
>> +
>> +&dsi1_phy {
>> +	vdds-supply = <&vreg_l1a_0p875>;
>> +	status = "okay";
>> +};
>> +
>> +&lt9611_codec {
>> +	ports {
>> +		port@1 {
>> +			reg = <1>;
>> +
>> +			lt9611_b: endpoint {
>> +				remote-endpoint = <&dsi1_out>;
>> +			};
>> +		};
>> +	};
>> +};
>> -- 
>> 2.39.0
>>