linux-kernel - Re: [PATCH 3/3] leds: add sgm3140 driver

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Message-ID: <2804366.mvXUDI8C0e@g550jk>
Date:   Mon, 09 Mar 2020 23:52:06 +0100
From:   Luca Weiss <luca@...tu.xyz>
To:     Sakari Ailus <sakari.ailus@....fi>, Pavel Machek <pavel@....cz>
Cc:     linux-leds@...r.kernel.org, Dan Murphy <dmurphy@...com>,
        Heiko Stuebner <heiko@...ech.de>,
        Icenowy Zheng <icenowy@...c.io>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mark Rutland <mark.rutland@....com>,
        Maxime Ripard <mripard@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH 3/3] leds: add sgm3140 driver

Hi Pavel

On Montag, 9. März 2020 23:49:27 CET Pavel Machek wrote:
> Hi!
> 
> > > +#define FLASH_TIMEOUT_DEFAULT		250000 /* 250ms */
> > > +#define FLASH_MAX_TIMEOUT_DEFAULT	300000 /* 300ms */
> > 
> > Add U, and you can remove the cast elsewhere.
> 
> I'll disagree here. Avoid U, avoid cast. Neither is needed.

If neither cast to u32 nor the U suffix is used, then this warning will be 
printed:

In file included from ./include/asm-generic/bug.h:19,
                 from ./arch/arm64/include/asm/bug.h:26,
                 from ./include/linux/bug.h:5,
                 from ./include/linux/gpio/consumer.h:5,
                 from drivers/leds/leds-sgm3140.c:4:
drivers/leds/leds-sgm3140.c: In function 'sgm3140_probe':
./include/linux/kernel.h:835:29: warning: comparison of distinct pointer types 
lacks a cast
  835 |   (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
      |                             ^~
./include/linux/kernel.h:849:4: note: in expansion of macro '__typecheck'
  849 |   (__typecheck(x, y) && __no_side_effects(x, y))
      |    ^~~~~~~~~~~
./include/linux/kernel.h:859:24: note: in expansion of macro '__safe_cmp'
  859 |  __builtin_choose_expr(__safe_cmp(x, y), \
      |                        ^~~~~~~~~~
./include/linux/kernel.h:868:19: note: in expansion of macro '__careful_cmp'
  868 | #define min(x, y) __careful_cmp(x, y, <)
      |                   ^~~~~~~~~~~~~
drivers/leds/leds-sgm3140.c:187:18: note: in expansion of macro 'min'
  187 |  priv->timeout = min(priv->max_timeout, FLASH_TIMEOUT_DEFAULT);
      |                  ^~~

So one of both is needed.

> 
> Best regards,
> 								
	Pavel

Regards
Luca