From: "Martin Povišer" <povik@cutebit.org>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Lee Jones <lee@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
Alyssa Rosenzweig <alyssa@rosenzweig.io>,
asahi@lists.linux.dev, Bartosz Golaszewski <brgl@bgdev.pl>,
Hector Martin <marcan@marcan.st>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Sven Peter <sven@svenpeter.dev>
Subject: Re: [PATCH 5/6] gpio: Add new gpio-macsmc driver for Apple Macs
Date: Fri, 2 Sep 2022 13:12:37 +0200 [thread overview]
Message-ID: <E753B391-D2CB-4213-AF82-678ADD5A7644@cutebit.org> (raw)
In-Reply-To: <CAHp75VeB3_sZ2vsSxMSsLeJSkyemDh9iOPHXJCN1mhodA13LNQ@mail.gmail.com>
Pardon, I lost the CC list in my earlier reply. Adding it back now.
> On 2. 9. 2022, at 12:23, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
>
> On Fri, Sep 2, 2022 at 12:47 PM Martin Povišer <povik@cutebit.org> wrote:
>>> On 2. 9. 2022, at 8:31, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
>>> On Fri, Sep 2, 2022 at 12:52 AM Martin Povišer <povik@cutebit.org> wrote:
>>>>> On 1. 9. 2022, at 20:55, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
>>>>> On Thu, Sep 1, 2022 at 5:17 PM Russell King <rmk+kernel@armlinux.org.uk> wrote:
>>>>
>>>>>> + ret = apple_smc_write_u32(smcgp->smc, key, CMD_OUTPUT | value);
>>>>>> + if (ret < 0)
>>>>>> + dev_err(smcgp->dev, "GPIO set failed %p4ch = 0x%x\n", &key, value);
>>>>>
>>>>> Strange specifier... It seems like a hashed pointer with added (or
>>>>> skipped? I don't remember) '4ch'. Perhaps you meant one of '%pE',
>>>>> '%p4cc'?
>>>>> Ditto for other cases.
>>>>
>>>> As was pointed out by Sven elsewhere in the thread, this is an
>>>> unupstreamed specifier (that was missed as a dependency of this
>>>> code).
>>>>
>>>> https://github.com/AsahiLinux/linux/blob/f8c0d18173a7b649999ee27515393f7aae40310c/Documentation/core-api/printk-formats.rst#generic-fourcc-code
>>>
>>> I don't see why we need that. The %.4s (0x%08x) is repeating that with
>>> the existing codebase. (I do understand why v4l2/drm have it). Ideally
>>> the first should use %4pE, but it might not be suitable in some cases.
>>
>> Just from a superficial understanding of things: %p4ch on little-endian
>> will print in a reversed order to %.4s. As I see it the handling of
>> endianness is the value proposition of the new specifiers.
>
> So, what prevents you from adding this to %pE?
> The preferred way is not adding a specifier for a single user with a
> particular case, esp. when it's covered by the existing ones.
Adding the endianness conversion into %pE as, ehm, an ‘escaping flag’?
If you think that would be accepted...
I guess this was added on the assumption that keys like this will
be a common occurrence in interaction with Apple firmware. Though
greping the ‘asahi’ staging tree for ‘%p4ch’ I only see it in the
SMC code (9 times):
./drivers/power/reset/macsmc-reboot.c
./drivers/platform/apple/smc_core.c
./drivers/gpio/gpio-macsmc.c
>> So
>>
>> %p4ch - interpret as an u32, print the character in most significant byte first
>
> %.4s + be32_to_cpu()
Well, AIUI instead of
printk(“%p4ch = ...\n”, &key);
you need to do
u32 key_be = cpu_to_be32(key);
printk(“%.4s = ...\n”, &key_be);
in at least 9 places now, the number of which will probably grow.
Just to make the case for *some* printk helper.
>
>> %p4cb - the same as %.4s
>
>> %p4cl - reversed to %.4s
>
> %.4s + swab32()
Sure, these two are uninteresting, probably added for completeness.
>
> So?
Well, so nothing. I am primarily explaining how that strange specifier
came to be.
Martin
> --
> With Best Regards,
> Andy Shevchenko
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next prev parent reply other threads:[~2022-09-02 11:14 UTC|newest]
Thread overview: 171+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-01 13:54 [PATCH 0/6] Add Apple Mac System Management Controller GPIOs Russell King (Oracle)
2022-09-01 13:54 ` [PATCH 1/6] dt-bindings: mfd: add binding for Apple Mac System Management Controller Russell King (Oracle)
2022-09-01 15:06 ` Krzysztof Kozlowski
2022-09-01 15:12 ` Russell King (Oracle)
2022-09-01 15:15 ` Krzysztof Kozlowski
2022-09-01 15:24 ` Russell King (Oracle)
2022-09-01 15:45 ` Krzysztof Kozlowski
2022-09-01 15:56 ` Russell King (Oracle)
2022-09-01 16:25 ` Krzysztof Kozlowski
2022-09-01 16:47 ` Russell King (Oracle)
2022-09-01 22:33 ` Rob Herring
2022-09-02 15:06 ` Mark Kettenis
2022-09-02 17:28 ` Rob Herring
2022-09-05 10:24 ` Russell King (Oracle)
2022-09-06 9:04 ` Russell King (Oracle)
2022-09-06 9:31 ` Mark Kettenis
2022-09-06 11:22 ` Linus Walleij
2022-09-06 11:36 ` Hector Martin
2022-09-06 11:57 ` Linus Walleij
2022-09-06 13:28 ` Hector Martin
2022-09-06 13:43 ` Russell King (Oracle)
2022-09-06 13:53 ` Hector Martin
2022-09-06 14:25 ` Mark Kettenis
2022-09-06 14:54 ` Russell King (Oracle)
2022-09-06 15:38 ` Mark Kettenis
2022-09-06 15:55 ` Rob Herring
2022-09-06 13:46 ` Linus Walleij
2022-09-06 15:34 ` Rob Herring
2022-09-06 16:10 ` Rob Herring
2022-09-06 17:00 ` Hector Martin
2022-09-06 17:35 ` Rob Herring
2022-09-06 17:40 ` Sven Peter
2022-09-06 18:38 ` Hector Martin
2022-09-07 9:39 ` Mark Kettenis
2022-09-01 22:26 ` Rob Herring
2022-09-02 14:49 ` Mark Kettenis
2022-09-02 17:04 ` Rob Herring
2022-09-01 19:14 ` Rob Herring
2022-09-01 13:54 ` [PATCH 2/6] dt-bindings: gpio: add binding for the GPIO block for Apple Mac SMC Russell King (Oracle)
2022-09-01 15:11 ` Krzysztof Kozlowski
2022-09-01 15:14 ` Russell King (Oracle)
2022-09-01 13:54 ` [PATCH 3/6] soc: apple: rtkit: Add apple_rtkit_poll Russell King
2022-09-01 17:00 ` Sven Peter
2022-09-01 17:25 ` Eric Curtin
2022-09-01 13:54 ` [PATCH 4/6] platform/apple: Add new Apple Mac SMC driver Russell King
2022-09-01 17:50 ` Sven Peter
2022-09-05 10:55 ` Russell King (Oracle)
2022-09-05 16:53 ` Hector Martin
2022-09-01 19:26 ` Andy Shevchenko
2022-09-02 6:45 ` Sven Peter
2022-09-05 14:45 ` Hector Martin
2022-09-05 15:00 ` Andy Shevchenko
2022-09-08 10:58 ` Lee Jones
2022-09-08 11:28 ` Hector Martin
2022-09-08 12:31 ` Lee Jones
2022-09-08 12:58 ` Hector Martin
2022-09-08 13:29 ` Linus Walleij
2022-09-08 13:36 ` Lee Jones
2022-09-08 13:58 ` Hector Martin
2022-09-09 7:50 ` Lee Jones
2022-09-12 10:03 ` Russell King (Oracle)
2022-09-12 10:55 ` Lee Jones
2022-10-28 15:36 ` Russell King (Oracle)
2022-10-31 8:46 ` Lee Jones
2022-10-31 9:03 ` Hector Martin
2022-10-31 9:44 ` Russell King (Oracle)
2022-10-31 17:24 ` Lee Jones
2022-10-31 19:47 ` Russell King (Oracle)
2022-11-01 9:59 ` Lee Jones
2022-10-29 6:40 ` Hector Martin
2022-10-31 8:48 ` Lee Jones
2022-10-31 8:58 ` Hector Martin
2022-10-31 9:29 ` Lee Jones
2022-10-31 9:44 ` Hector Martin
2022-10-31 17:23 ` Lee Jones
2022-10-31 19:34 ` Russell King (Oracle)
2022-11-02 13:12 ` Lee Jones
2022-11-02 15:54 ` Russell King (Oracle)
2022-09-01 13:54 ` [PATCH 5/6] gpio: Add new gpio-macsmc driver for Apple Macs Russell King
2022-09-01 18:55 ` Andy Shevchenko
2022-09-01 21:51 ` Martin Povišer
2022-09-02 6:31 ` Andy Shevchenko
[not found] ` <3B649A66-8116-432D-B88A-B5CE493EF930@cutebit.org>
[not found] ` <CAHp75VeB3_sZ2vsSxMSsLeJSkyemDh9iOPHXJCN1mhodA13LNQ@mail.gmail.com>
2022-09-02 11:12 ` Martin Povišer [this message]
2022-09-02 13:33 ` Andy Shevchenko
2022-09-02 13:36 ` Andy Shevchenko
2022-09-02 13:37 ` Martin Povišer
2022-09-02 14:41 ` Andy Shevchenko
2022-09-02 14:45 ` Russell King (Oracle)
2022-09-02 10:05 ` Russell King (Oracle)
2022-09-02 10:37 ` Andy Shevchenko
2022-09-02 11:32 ` Russell King (Oracle)
2022-09-02 13:39 ` Andy Shevchenko
2022-09-02 14:46 ` Russell King (Oracle)
2022-09-02 14:53 ` Andy Shevchenko
2022-09-02 15:34 ` Russell King (Oracle)
2022-09-02 15:43 ` Andy Shevchenko
2022-09-05 10:20 ` Russell King (Oracle)
2022-09-05 10:32 ` Andy Shevchenko
2022-09-05 13:10 ` Russell King (Oracle)
2022-09-05 13:16 ` Andy Shevchenko
2022-09-05 14:01 ` Russell King (Oracle)
2022-09-05 14:02 ` Russell King (Oracle)
2022-09-05 14:42 ` Andy Shevchenko
2022-09-05 14:53 ` Russell King (Oracle)
2022-09-05 14:50 ` Andy Shevchenko
2022-09-05 15:52 ` Hector Martin
2022-09-05 15:56 ` Russell King (Oracle)
2022-09-05 15:32 ` Russell King (Oracle)
2022-09-05 15:44 ` Martin Povišer
2022-09-05 15:58 ` Hector Martin
2022-09-05 16:13 ` Russell King (Oracle)
2022-09-05 19:10 ` Linus Walleij
2022-09-06 6:51 ` Hector Martin
2022-09-05 15:47 ` Hector Martin
2022-09-05 15:39 ` Hector Martin
2022-09-05 15:16 ` Hector Martin
2022-09-05 15:04 ` Hector Martin
2022-09-02 9:42 ` Linus Walleij
2022-09-01 13:54 ` [PATCH 6/6] gpio: macsmc: Add IRQ support Russell King
2022-09-01 18:03 ` Andy Shevchenko
2022-09-05 11:54 ` Russell King (Oracle)
[not found] ` <CAHp75VeDGCp8J6wnmCqGpV++vs2Zur9Mfp71Dk8dVXcuHFnCrQ@mail.gmail.com>
2022-09-05 13:21 ` Andy Shevchenko
2022-09-02 13:21 ` Linus Walleij
2022-09-05 12:47 ` Russell King (Oracle)
2022-09-05 13:19 ` Fwd: " Andy Shevchenko
2022-09-05 21:43 ` Russell King (Oracle)
2022-09-05 13:27 ` Linus Walleij
2022-09-06 7:00 ` Hector Martin
2022-09-06 7:47 ` Russell King (Oracle)
2022-09-06 8:00 ` Hector Martin
2022-09-01 15:12 ` [PATCH 0/6] Add Apple Mac System Management Controller GPIOs Krzysztof Kozlowski
2022-10-27 15:35 ` Russell King (Oracle)
2022-11-08 16:32 ` [PATCH v3 0/7] " Russell King (Oracle)
2022-11-08 16:33 ` [PATCH v3 1/7] mfd: Add core Apple Mac SMC driver Russell King
2022-11-14 9:52 ` Lee Jones
2022-11-14 10:35 ` Andy Shevchenko
2022-11-08 16:33 ` [PATCH v3 2/7] lib/vsprintf: Add support for generic FOURCCs by extending %p4cc Russell King
2022-11-14 15:34 ` Petr Mladek
2022-11-14 15:46 ` Andy Shevchenko
2022-11-14 16:18 ` Petr Mladek
2022-11-14 16:15 ` Russell King (Oracle)
2022-11-14 16:46 ` Russell King (Oracle)
2022-11-22 12:43 ` Petr Mladek
2022-11-22 14:49 ` Petr Mladek
2022-11-08 16:33 ` [PATCH v3 3/7] dt-bindings: mfd: add binding for Apple Mac System Management Controller Russell King (Oracle)
2022-11-08 20:42 ` Linus Walleij
2022-11-08 20:55 ` Krzysztof Kozlowski
2022-11-08 22:22 ` Russell King (Oracle)
2022-11-09 8:35 ` Krzysztof Kozlowski
2022-11-09 22:17 ` Rob Herring
2022-11-10 11:35 ` Hector Martin
2022-11-10 11:48 ` Russell King (Oracle)
2022-11-10 14:00 ` Krzysztof Kozlowski
2022-11-10 14:14 ` Russell King (Oracle)
2022-11-10 14:21 ` Krzysztof Kozlowski
2022-11-10 14:23 ` Russell King (Oracle)
2022-11-10 14:36 ` Krzysztof Kozlowski
2022-11-10 14:43 ` Russell King (Oracle)
2022-11-14 10:05 ` Lee Jones
2022-11-08 22:30 ` Rob Herring
2022-11-08 16:33 ` [PATCH v3 4/7] platform/apple: Add new Apple Mac SMC driver Russell King
2022-11-08 16:33 ` [PATCH v3 5/7] arm64: dts: apple: Add SMC node to t8103 devicetrees Russell King
2022-11-08 16:33 ` [PATCH v3 6/7] dt-bindings: gpio: add binding for the GPIO block for Apple Mac SMC Russell King (Oracle)
2022-11-08 20:56 ` Krzysztof Kozlowski
2022-11-08 22:09 ` Russell King (Oracle)
2022-11-09 7:31 ` Hector Martin
2022-11-09 8:36 ` Krzysztof Kozlowski
2022-11-09 9:12 ` Russell King (Oracle)
2022-11-09 9:19 ` Krzysztof Kozlowski
2022-11-08 22:30 ` Rob Herring
2022-11-08 16:33 ` [PATCH v3 7/7] gpio: Add new gpio-macsmc driver for Apple Macs Russell King
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