From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: "Martin Povišer" <povik@cutebit.org>,
"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 15:45:34 +0100 [thread overview]
Message-ID: <YxIXDrP7XN5r1hCs@shell.armlinux.org.uk> (raw)
In-Reply-To: <85AE2F3E-6A1D-4AA0-9205-3E3DE5C6D79F@cutebit.org>
On Fri, Sep 02, 2022 at 03:37:27PM +0200, Martin Povišer wrote:
>
> > On 2. 9. 2022, at 15:33, Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> >
> > On Fri, Sep 2, 2022 at 2:12 PM Martin Povišer <povik@cutebit.org> wrote:
> >>> 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:
> >
> > ...
> >
> >>>>> 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
> >
> >>>> %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.
> >
> > Wouldn't this be one line
> >
> > printk(“%.4s = ...\n”, &cpu_to_be32(key));
> >
> > ?
>
> That would compile? I thought that’s not valid C, taking an
> address of function’s return value.
It isn't legal C.
int foo(int bar);
int blah(int *v);
int test(int v)
{
return blah(&foo(v));
}
t.c: In function ‘test’:
t.c:7:14: error: lvalue required as unary ‘&’ operand
And just to make sure that it's not just my test that is wrong, and
there's something magical about cpu_to_be32()...
In file included from include/linux/device.h:15,
from drivers/gpio/gpio-macsmc.c:11:
drivers/gpio/gpio-macsmc.c: In function 'macsmc_gpio_probe':
drivers/gpio/gpio-macsmc.c:356:49: error: lvalue required as unary '&' operand
356 | dev_info(smcgp->dev, "First GPIO key: %.4s\n", &cpu_to_be32(key));
| ^
include/linux/dev_printk.h:110:23: note: in definition of macro 'dev_printk_index_wrap'
110 | _p_func(dev, fmt, ##__VA_ARGS__); \
| ^~~~~~~~~~~
drivers/gpio/gpio-macsmc.c:356:2: note: in expansion of macro 'dev_info'
356 | dev_info(smcgp->dev, "First GPIO key: %.4s\n", &cpu_to_be32(key));
| ^~~~~~~~
make[3]: *** [scripts/Makefile.build:249: drivers/gpio/gpio-macsmc.o] Error 1
make[2]: *** [scripts/Makefile.build:466: drivers/gpio] Error 2
make[1]: *** [Makefile:1843: drivers] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:219: __sub-make] Error 2
So, sorry Andy, but this suggestion does not appear to be legal C.
This also applies to your suggestion in the other sub-thread of:
ret = hex2bin(&result, (char *)&cpu_to_le16(key), 1);
As we've now discovered that this is not legal C, can we back up *both*
discussions and start again on these points.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
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next prev parent reply other threads:[~2022-09-02 14:50 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
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) [this message]
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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