Re: [PATCH 1/1] arm64: dts: qcom: msm8994: Reserve gpio ranges

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Mon 05 Apr 15:02 CDT 2021, Petr Vorel wrote:

> Reserve pins 0-3 and 85-88 as these aren't meant to be accessible
> from the application CPUs. Fix similar to 9134586715e3.
> 
> Fixes: 3edfb7bd76bd ("gpiolib: Show correct direction from the beginning")
> 
> Signed-off-by: Petr Vorel <petr.vorel@gmail.com>
> ---
> Hi,
> 
> tested on latest qcom/for-next.
> 
> Simple testing with /sys/class/gpio/export showed that 85-88.
> 3 disables UART. I expect 0-2 are also reserved as on other msm8998.
> 

Are you saying that once you export these gpios the uart stops working?

We use gpio-reserved-ranges to denote GPIOs that are owned by TZ, so
touching their registers causes the device to reboot. And per the
gpiolib patch you reference, this would happen as we register the
gpiochip.

It sounds instead like what you want is to make sure that these pins are
considered busy, muxing in the uart (i.e define a state for uart).

Regards,
Bjorn

> for i in $(seq 0 146); do echo $i > /sys/class/gpio/export; done
> 
> I expect it's just angler specific, thus I haven't added it to msm8994.dtsi
> (otherwise Konrad would have fixed it).
> 
> Kind regards,
> Petr
> 
>  arch/arm64/boot/dts/qcom/msm8994-angler-rev-101.dts | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/msm8994-angler-rev-101.dts b/arch/arm64/boot/dts/qcom/msm8994-angler-rev-101.dts
> index baa55643b40f..0dc94101d5de 100644
> --- a/arch/arm64/boot/dts/qcom/msm8994-angler-rev-101.dts
> +++ b/arch/arm64/boot/dts/qcom/msm8994-angler-rev-101.dts
> @@ -1,6 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0-only
>  /* Copyright (c) 2015, Huawei Inc. All rights reserved.
>   * Copyright (c) 2016, The Linux Foundation. All rights reserved.
> + * Copyright (c) 2021 Petr Vorel <petr.vorel@gmail.com>
>   */
>  
>  /dts-v1/;
> @@ -32,3 +33,7 @@ serial@f991e000 {
>  		};
>  	};
>  };
> +
> +&tlmm {
> +	gpio-reserved-ranges = <0 4>, <85 4>;
> +};
> -- 
> 2.30.2
>