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Message-ID: <fd5cc541-dfc6-d1cf-0865-669b11ce2e7a@xen0n.name>
Date: Tue, 15 Nov 2022 18:17:23 +0800
From: WANG Xuerui <kernel@...0n.name>
To: Yinbo Zhu <zhuyinbo@...ngson.cn>,
Bartosz Golaszewski <brgl@...ev.pl>
Cc: Linus Walleij <linus.walleij@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Jiaxun Yang <jiaxun.yang@...goat.com>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Juxin Gao <gaojuxin@...ngson.cn>,
Bibo Mao <maobibo@...ngson.cn>,
Yanteng Si <siyanteng@...ngson.cn>, linux-gpio@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
loongarch@...ts.linux.dev, linux-mips@...r.kernel.org,
Arnaud Patard <apatard@...driva.com>,
Huacai Chen <chenhuacai@...nel.org>,
lvjianmin <lvjianmin@...ngson.cn>,
zhanghongchen <zhanghongchen@...ngson.cn>,
Liu Peibao <liupeibao@...ngson.cn>
Subject: Re: [PATCH v2 1/2] gpio: loongson: add dts/acpi gpio support
Sorry for jumping in, but...
On 2022/11/15 17:53, Yinbo Zhu wrote:
>
>
> 在 2022/11/15 下午5:05, Bartosz Golaszewski 写道:
>> On Mon, Nov 14, 2022 at 10:53 AM Yinbo Zhu <zhuyinbo@...ngson.cn> wrote:
>>>
>>> The latest Loongson series platform use dts or acpi framework to
>>> register gpio device resources, such as the Loongson-2 series
>>> SoC of LOONGARCH architecture. In order to support dts, acpi and
>>> compatibility with previous platform device resources in driver,
>>> this patch was added.
>>>
>>> Signed-off-by: lvjianmin <lvjianmin@...ngson.cn>
>>> Signed-off-by: zhanghongchen <zhanghongchen@...ngson.cn>
>>> Signed-off-by: Liu Peibao <liupeibao@...ngson.cn>
>>> Signed-off-by: Juxin Gao <gaojuxin@...ngson.cn>
>>> Signed-off-by: Yinbo Zhu <zhuyinbo@...ngson.cn>
>>> ---
>>> Change in v2:
>>> 1. Fixup of_loongson_gpio_get_props and remove the
>>> parse logic about
>>> "loongson,conf_offset", "loongson,out_offset",
>>> "loongson,in_offset",
>>> "loongson,gpio_base", "loongson,support_irq" then
>>> kernel driver will
>>> initial them that depend compatible except
>>> "loongson,gpio_base".
>>>
>>> arch/loongarch/include/asm/loongson.h | 13 +
>>> .../include/asm/mach-loongson2ef/loongson.h | 12 +
>>> .../include/asm/mach-loongson64/loongson.h | 13 +
>>> drivers/gpio/Kconfig | 6 +-
>>> drivers/gpio/gpio-loongson.c | 422 +++++++++++++++---
>>> 5 files changed, 391 insertions(+), 75 deletions(-)
>>>
>>> diff --git a/arch/loongarch/include/asm/loongson.h
>>> b/arch/loongarch/include/asm/loongson.h
>>> index 00db93edae1b..383fdda155f0 100644
>>> --- a/arch/loongarch/include/asm/loongson.h
>>> +++ b/arch/loongarch/include/asm/loongson.h
>>> @@ -60,6 +60,19 @@ static inline void xconf_writeq(u64 val64,
>>> volatile void __iomem *addr)
>>> );
>>> }
>>>
>>> +/* ============== Data structrues =============== */
>>> +
>>> +/* gpio data */
>>> +struct platform_gpio_data {
>>> + u32 gpio_conf;
>>> + u32 gpio_out;
>>> + u32 gpio_in;
>>> + u32 support_irq;
>>> + char *label;
>>> + int gpio_base;
>>> + int ngpio;
>>> +};
>>
>> This is a terrible name for an exported structure. You would at least
>> need some kind of a namespace prefix. But even then the need to add a
>> platform data structure is very questionable. We've moved past the
>> need for platform data in the kernel. I don't see anyone setting it up
>> in this series either. Could you provide more explanation on why you
>> would need it and who would use it?
> okay, I will add a namespace prefix, about this platform data was added
> that was to compatible with legacy platforms that do not support dts or
> acpi, then, the mips loongson platform or loongarch loongson platform
Why are you trying to support "legacy" LoongArch platforms when the
architecture was just upstreamed *this year*?
> can implement the gpio device driver to initialize the
> platform_gpio_data structure as needed after exporting the structure.
>>
>>> +
>>> /* ============== LS7A registers =============== */
>>> #define LS7A_PCH_REG_BASE 0x10000000UL
>>> /* LPC regs */
>>> diff --git a/arch/mips/include/asm/mach-loongson2ef/loongson.h
>>> b/arch/mips/include/asm/mach-loongson2ef/loongson.h
>>> index ca039b8dcde3..b261cea4fee1 100644
>>> --- a/arch/mips/include/asm/mach-loongson2ef/loongson.h
>>> +++ b/arch/mips/include/asm/mach-loongson2ef/loongson.h
>>> @@ -315,4 +315,16 @@ extern unsigned long _loongson_addrwincfg_base;
>>>
>>> #endif /* ! CONFIG_CPU_SUPPORTS_ADDRWINCFG */
>>>
>>> +/* ============== Data structrues =============== */
>>> +
>>> +/* gpio data */
>>> +struct platform_gpio_data {
>>> + u32 gpio_conf;
>>> + u32 gpio_out;
>>> + u32 gpio_in;
>>> + u32 support_irq;
>>> + char *label;
>>> + int gpio_base;
>>> + int ngpio;
>>> +};
>>
>> No idea why you would need to duplicate it like this either. And why
>> put it in arch/.
> because loongson platform include mips and loongarch, and the gpio
> device data was defined in arch/ in leagcy loongson gpio driver. so the
> latest loongson gpio drvier add platform_gpio_data in same dir.
I think at this point it's hopefully clear, that the way forward to
supporting Loongson IP blocks shared between MIPS/LoongArch SoCs is to
start over and do things properly, making the code as platform-agnostic
as possible. Just make sure the drivers can get initialized via DT and
ACPI then you're all set -- the upstream kernel is guaranteed to use one
of the two well-established boot flows for every Loongson chip it
supports. Be it hard-coded DT in arch/mips/boot/dts/loongson, or the
LoongArch ACPI/upcoming DT, no need for hard-coding things in arch/ in
either case.
>>
>> [snip]
>>
>> I will hold off reviewing the rest of the patch until we get that
>> clarified.
>>
>> Bartosz
>>
>
--
WANG "xen0n" Xuerui
Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/
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