Re: [PATCH v4 7/7] arm64: dts: exynos: Add initial device tree support for Exynos7885 SoC

From: Sam Protsenko <semen.protsenko@linaro.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Cc: David Virag <virag.david003@gmail.com>,
	Rob Herring <robh+dt@kernel.org>,
	Sylwester Nawrocki <s.nawrocki@samsung.com>,
	Tomasz Figa <tomasz.figa@gmail.com>,
	Chanwoo Choi <cw00.choi@samsung.com>,
	Michael Turquette <mturquette@baylibre.com>,
	Stephen Boyd <sboyd@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org
Subject: Re: [PATCH v4 7/7] arm64: dts: exynos: Add initial device tree support for Exynos7885 SoC
Date: Wed, 8 Dec 2021 18:51:45 +0200	[thread overview]
Message-ID: <CAPLW+4kmt1fEWG14jLJmPM0uHoyf017U7rigri47KT9Tamto=Q@mail.gmail.com> (raw)
In-Reply-To: <a7d5f290-7992-b37c-fe2c-90bf3e5e83ce@canonical.com>

On Wed, 8 Dec 2021 at 18:29, Krzysztof Kozlowski
<krzysztof.kozlowski@canonical.com> wrote:
>
> On 08/12/2021 16:37, Sam Protsenko wrote:
> > On Wed, 8 Dec 2021 at 11:05, Krzysztof Kozlowski
> > <krzysztof.kozlowski@canonical.com> wrote:
> >>
> >> On 07/12/2021 21:19, Sam Protsenko wrote:
> >>> On Mon, 6 Dec 2021 at 17:32, David Virag <virag.david003@gmail.com> wrote:
> >>>>
> >>>> Add initial Exynos7885 device tree nodes with dts for the Samsung Galaxy
> >>>> A8 (2018), a.k.a. "jackpotlte", with model number "SM-A530F".
> >>>> Currently this includes some clock support, UART support, and I2C nodes.
> >>>>
> >>>> Signed-off-by: David Virag <virag.david003@gmail.com>
> >>>> ---
> >>>> Changes in v2:
> >>>>   - Remove address-cells, and size-cells from dts, since they are
> >>>>     already in the dtsi.
> >>>>   - Lower case hex in memory node
> >>>>   - Fix node names with underscore instead of hyphen
> >>>>   - Fix line breaks
> >>>>   - Fix "-key" missing from gpio keys node names
> >>>>   - Use the form without "key" in gpio key labels on all keys
> >>>>   - Suffix pin configuration node names with "-pins"
> >>>>   - Remove "fimc_is_mclk" nodes from pinctrl dtsi for now
> >>>>   - Use macros for "samsung,pin-con-pdn", and "samsung,pin-con-pdn"
> >>>>   - Add comment about Arm PMU
> >>>>   - Rename "clock-oscclk" to "osc-clock"
> >>>>   - Include exynos-syscon-restart.dtsi instead of rewriting its contents
> >>>>
> >>>> Changes in v3:
> >>>>   - Fix typo (seperate -> separate)
> >>>>
> >>>> Changes in v4:
> >>>>   - Fixed leading 0x in clock-controller nodes
> >>>>   - Actually suffixed pin configuration node names with "-pins"
> >>>>   - Seperated Cortex-A53 and Cortex-A73 PMU
> >>>>
> >>>>  arch/arm64/boot/dts/exynos/Makefile           |   7 +-
> >>>>  .../boot/dts/exynos/exynos7885-jackpotlte.dts |  95 ++
> >>>>  .../boot/dts/exynos/exynos7885-pinctrl.dtsi   | 865 ++++++++++++++++++
> >>>>  arch/arm64/boot/dts/exynos/exynos7885.dtsi    | 438 +++++++++
> >>>>  4 files changed, 1402 insertions(+), 3 deletions(-)
> >>>>  create mode 100644 arch/arm64/boot/dts/exynos/exynos7885-jackpotlte.dts
> >>>
> >>> Shouldn't SoC and board files be sent as two separate patches? For
> >>> example, I've checked exynos5433 and exynos7, SoC support
> >>
> >> Does not have to be. DTSI by itself cannot be even compiled, so keeping
> >> it a separate commit does not bring that much benefits. Especially if it
> >> is only one DTSI and one DTS.
> >>
> >
> > Right, the only theoretical benefit I can see is reverting the board
> > dts in future, if another board already uses SoC dtsi. Or
> > cherry-picking in similar manner. Not my call though, for me it just
> > seems easier to review it that way, and more atomic.
> >
> >>>
> >>>>  create mode 100644 arch/arm64/boot/dts/exynos/exynos7885-pinctrl.dtsi
> >>>>  create mode 100644 arch/arm64/boot/dts/exynos/exynos7885.dtsi
> >>>>
> >>>> diff --git a/arch/arm64/boot/dts/exynos/Makefile b/arch/arm64/boot/dts/exynos/Makefile
> >>>> index b41e86df0a84..c68c4ad577ac 100644
> >>>> --- a/arch/arm64/boot/dts/exynos/Makefile
> >>>> +++ b/arch/arm64/boot/dts/exynos/Makefile
> >>>> @@ -1,6 +1,7 @@
> >>>>  # SPDX-License-Identifier: GPL-2.0
> >>>>  dtb-$(CONFIG_ARCH_EXYNOS) += \
> >>>> -       exynos5433-tm2.dtb      \
> >>>> -       exynos5433-tm2e.dtb     \
> >>>> -       exynos7-espresso.dtb    \
> >>>> +       exynos5433-tm2.dtb              \
> >>>> +       exynos5433-tm2e.dtb             \
> >>>> +       exynos7-espresso.dtb            \
> >>>> +       exynos7885-jackpotlte.dtb       \
> >>>>         exynosautov9-sadk.dtb
> >>>> diff --git a/arch/arm64/boot/dts/exynos/exynos7885-jackpotlte.dts b/arch/arm64/boot/dts/exynos/exynos7885-jackpotlte.dts
> >>>> new file mode 100644
> >>>> index 000000000000..f5941dc4c374
> >>>> --- /dev/null
> >>>> +++ b/arch/arm64/boot/dts/exynos/exynos7885-jackpotlte.dts
> >>>> @@ -0,0 +1,95 @@
> >>>> +// SPDX-License-Identifier: GPL-2.0
> >>>> +/*
> >>>> + * Samsung Galaxy A8 2018 (jackpotlte/SM-A530F) device tree source
> >>>> + *
> >>>> + * Copyright (c) 2021 Samsung Electronics Co., Ltd.
> >>>> + * Copyright (c) 2021 Dávid Virág
> >>>> + *
> >>>
> >>> This line is not needed.
> >>>
> >>>> + */
> >>>> +
> >>>> +/dts-v1/;
> >>>
> >>> Suggest adding empty line here.
> >>>
> >>>> +#include "exynos7885.dtsi"
> >>>> +#include <dt-bindings/gpio/gpio.h>
> >>>> +#include <dt-bindings/input/input.h>
> >>>> +#include <dt-bindings/interrupt-controller/irq.h>
> >>>> +
> >>>> +/ {
> >>>> +       model = "Samsung Galaxy A8 (2018)";
> >>>> +       compatible = "samsung,jackpotlte", "samsung,exynos7885";
> >>>> +       chassis-type = "handset";
> >>>> +
> >>>> +       aliases {
> >>>> +               serial0 = &serial_0;
> >>>> +               serial1 = &serial_1;
> >>>> +               serial2 = &serial_2;
> >>>
> >>> Suggestion: add aliases also for i2c nodes, to keep i2c instance
> >>> numbers fixed in run-time (e.g. in "i2cdetect -l" output).
> >>>
> >>>> +       };
> >>>> +
> >>>> +       chosen {
> >>>> +               stdout-path = &serial_2;
> >>>> +       };
> >>>> +
> >>>> +       memory@80000000 {
> >>>> +               device_type = "memory";
> >>>> +               reg = <0x0 0x80000000 0x3da00000>,
> >>>> +                     <0x0 0xc0000000 0x40000000>,
> >>>> +                     <0x8 0x80000000 0x40000000>;
> >>>> +       };
> >>>> +
> >>>> +       gpio-keys {
> >>>> +               compatible = "gpio-keys";
> >>>> +               pinctrl-names = "default";
> >>>> +               pinctrl-0 = <&key_volup &key_voldown &key_power>;
> >>>> +
> >>>> +               volup-key {
> >>>> +                       label = "Volume Up";
> >>>> +                       interrupts = <5 IRQ_TYPE_LEVEL_HIGH 0>;
> >>>
> >>> Here and below: what is 0, why it's needed? Also, isn't it enough to
> >>> have just "gpios", and remove interrupt*? Need to check "gpio-keys"
> >>> driver and bindings doc, but AFAIR it should be enough to have just
> >>> "gpios =" or just "interrupts =".
> >>
> >> "gpios" is enough, because the IRQ line is derived from it. However
> >> explicitly describing interrupts seems like a more detailed hardware
> >> description.
> >>
> >
> > Frankly I don't think it's more detailed, it states the same thing
> > (gpa1 controller, line=5).
>
> It states that interrupt is exactly the same as GPIO which not
> explicitly coming from bindings.
>
> > Also not sure if level interrupt is needed
> > for a key, maybe edge type would be better. Also, I still don't
> > understand 0 in the end.
>
> Indeed this part looks not correct - the leve and 0 at the end. In such
> case better to skip it then define misleading property.
>
> > Checking existing dts's, most of those only
> > define "gpios". I'd say having only "gpios" is more obvious, and will
> > work the same way. But that's not a strong preference on my side, just
> > think it's a bit misleading right now.
>
> Yep.
>
> >
> >>>
> >>>
> >>>> +                       interrupt-parent = <&gpa1>;
> >>>> +                       linux,code = <KEY_VOLUMEUP>;
> >>>> +                       gpios = <&gpa1 5 GPIO_ACTIVE_LOW>;
> >>>> +               };
> >>>> +
> >>>> +               voldown-key {
> >>>> +                       label = "Volume Down";
> >>>> +                       interrupts = <6 IRQ_TYPE_LEVEL_HIGH 0>;
> >>>> +                       interrupt-parent = <&gpa1>;
> >>>> +                       linux,code = <KEY_VOLUMEDOWN>;
> >>>> +                       gpios = <&gpa1 6 GPIO_ACTIVE_LOW>;
> >>>> +               };
> >>>> +
> >>>> +               power-key {
> >>>> +                       label = "Power";
> >>>> +                       interrupts = <7 IRQ_TYPE_LEVEL_HIGH 0>;
> >>>> +                       interrupt-parent = <&gpa1>;
> >>>> +                       linux,code = <KEY_POWER>;
> >>>> +                       gpios = <&gpa1 7 GPIO_ACTIVE_LOW>;
> >>>> +                       wakeup-source;
> >>>> +               };
> >>>> +       };
> >>>> +};
> >>>> +
> >>>
> >>> If there are some LEDs by chance on that board -- it might be useful
> >>> to define those here with "gpio-leds" as well. Maybe even set some
> >>> default trigger like "heartbeat".
> >>>
> >>>> +&serial_2 {
> >>>> +       status = "okay";
> >>>> +};
> >>>> +
> >>>> +&pinctrl_alive {
> >>>> +       key_volup: key-volup-pins {
> >>>> +               samsung,pins = "gpa1-5";
> >>>> +               samsung,pin-function = <EXYNOS_PIN_FUNC_F>;
> >>>
> >>> Maybe EXYNOS_PIN_FUNC_EINT is more self-explanatory? Just a suggestion though.
> >>>
> >>>> +               samsung,pin-pud = <EXYNOS_PIN_PULL_NONE>;
> >>>> +               samsung,pin-drv = <0>;
> >>>
> >>> Here and below: please use EXYNOS5420_PIN_DRV_LV1 (means drive level = 1x).
> >>
> >> But are these drive level 1x? The Exynos Auto v9 has different values
> >> than older ones.
> >>
> >
> > It should be that. One way to implicitly figure that out is to look at
> > nodes like "sd0_clk_fast_slew_rate_3x" and those pin-drv properties.
> > Also, in Exynos850 for most of domains those constants are
> > appropriate, that's why I mentioned that.
>
> Then I agree, use existing macros. The macros can be skipped for cases
> when the meaning is different.
>
> >
> >>>
> >>>> +       };
> >>>> +
> >>>> +       key_voldown: key-voldown-pins {
> >>>> +               samsung,pins = "gpa1-6";
> >>>> +               samsung,pin-function = <EXYNOS_PIN_FUNC_F>;
> >>>> +               samsung,pin-pud = <EXYNOS_PIN_PULL_NONE>;
> >>>> +               samsung,pin-drv = <0>;
> >>>> +       };
> >>>> +
> >>>> +       key_power: key-power-pins {
> >>>> +               samsung,pins = "gpa1-7";
> >>>> +               samsung,pin-function = <EXYNOS_PIN_FUNC_F>;
> >>>> +               samsung,pin-pud = <EXYNOS_PIN_PULL_NONE>;
> >>>> +               samsung,pin-drv = <0>;
> >>>> +       };
> >>>> +};
> >>>> diff --git a/arch/arm64/boot/dts/exynos/exynos7885-pinctrl.dtsi b/arch/arm64/boot/dts/exynos/exynos7885-pinctrl.dtsi
> >>>> new file mode 100644
> >>>> index 000000000000..8336b2e48858
> >>>> --- /dev/null
> >>>> +++ b/arch/arm64/boot/dts/exynos/exynos7885-pinctrl.dtsi
> >>>> @@ -0,0 +1,865 @@
> >>>> +// SPDX-License-Identifier: GPL-2.0
> >>>> +/*
> >>>> + * Samsung Exynos7885 SoC pin-mux and pin-config device tree source
> >>>> + *
> >>>> + * Copyright (c) 2017 Samsung Electronics Co., Ltd.
> >>>> + * Copyright (c) 2021 Dávid Virág
> >>>> + *
> >>>> + * Samsung's Exynos7885 SoC pin-mux and pin-config options are listed as
> >>>> + * device tree nodes in this file.
> >>>> + */
> >>>> +
> >>>> +#include <dt-bindings/pinctrl/samsung.h>
> >>>
> >>> You probably also need <dt-bindings/interrupt-controller/arm-gic.h>
> >>> here for GIC_SPI definition.
> >>>
> >>>> +
> >>>> +&pinctrl_alive {
> >>>> +       etc0: etc0 {
> >>>> +               gpio-controller;
> >>>> +               #gpio-cells = <2>;
> >>>> +
> >>>> +               interrupt-controller;
> >>>> +               #interrupt-cells = <2>;
> >>>> +       };
> >>>> +
> >>>> +       etc1: etc1 {
> >>>> +               gpio-controller;
> >>>> +               #gpio-cells = <2>;
> >>>> +
> >>>> +               interrupt-controller;
> >>>> +               #interrupt-cells = <2>;
> >>>> +       };
> >>>
> >>> Hmm, what are these two? I can't find anything related in
> >>> exynos7885.dtsi. If it's just some leftover from downstream vendor
> >>> kernel -- please remove it.
> >>
> >> This is a pinctrl DTSI file. What do you expect to find in
> >> exynos7885.dtsi for these? Why removing them?
> >
> > etc0 and etc1 nodes are defined as gpio-controller and
> > interrupt-controller. So "compatible" should be provided somewhere for
> > those nodes. For example, for "gpa0" node below you can find its
> > compatible in exynos7885.dtsi.
>
> I am sorry, I still don't get it. gpa0 below does not have compatible.
>

I was probably groggy and missed the fact those etc* nodes are child
nodes of pinctrl_alive :) And now I can see those are actually
described in pinctrl-exynos-arm64.c (in linux-next, where 7885 pinctrl
support is added). Please ignore my request w.r.t. etc* nodes, those
should stay of course.

> > Right now I don't understand how those
> > etc0 and etc1 can be used at all.
>
> Exactly the same as gpa0, nothing changes here.
>
> >  So maybe it's better to just remove
> > those? Those are not used anywhere and we probably don't even know
> > what those nodes represent. My point is, if those are actually some
> > leftovers from vendor kernel and those are not going to be used (and I
> > don't see how, without "compatible"), then we probablly better off
> > without those.
>
> I don't have the manual but in other SoCs these are not left-overs, but
> real GPIO banks. Their configurability depends on the SoCs. I agree that
> usually they are not used (because one of the uses is debugging), but
> they can be included for completness of HW description. Assuming they exist.
>
> (...)
>
> >>>> +#include "exynos7885-pinctrl.dtsi"
> >>>> +#include "arm/exynos-syscon-restart.dtsi"
> >>>
> >>> Have you verified both reboot and power off functions from this file?
> >>> I guess if some doesn't work, it's better to avoid including this, but
> >>> instead add corresponding sub-nodes into your pmu_sytem_controller.
> >>
> >> Why open-coding same code work and including would not? Assuming that it
> >> compiles, of course.
> >>
> >
> > For example, in case of Exynos850 the "power off" node from this file
> > wasn't suitable. In that case it's not worth including it. But David
> > already confirmed both work fine for him, so it doesn't matter
> > anymore.
>
> These nodes were here before and since they duplicated common syscon, I
> asked to use DTSI. The boards which do not use the same syscon
> registers/methods should not include it, obviously. :)
>
>
> Best regards,
> Krzysztof