Re: [PATCH v18 3/3] Input: new da7280 haptic driver - Uwe Kleine-König

From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Roy Im <roy.im.opensource@diasemi.com>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Brian Masney <masneyb@onstation.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	Lee Jones <lee.jones@linaro.org>, Luca Weiss <luca@z3ntu.xyz>,
	Maximilian Luz <luzmaximilian@gmail.com>,
	Pascal PAILLET-LME <p.paillet@st.com>,
	Rob Herring <robh@kernel.org>,
	Samuel Ortiz <sameo@linux.intel.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Support Opensource <support.opensource@diasemi.com>,
	linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-pwm@vger.kernel.org, Petr Mladek <pmladek@suse.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>
Subject: Re: [PATCH v18 3/3] Input: new da7280 haptic driver
Date: Thu, 30 Jul 2020 08:16:31 +0200	[thread overview]
Message-ID: <20200730061631.y4r4s6v3xepktj54@pengutronix.de> (raw)
In-Reply-To: <20200730050653.GA1665100@dtor-ws>

[-- Attachment #1: Type: text/plain, Size: 2180 bytes --]

[Adding vsprintf maintainers to Cc:]

Hello,

On Wed, Jul 29, 2020 at 10:06:53PM -0700, Dmitry Torokhov wrote:
> On Wed, Jul 29, 2020 at 09:21:45AM +0200, Uwe Kleine-König wrote:
> > Hello,
> > 
> > On Tue, Jul 28, 2020 at 11:36:38PM -0700, Dmitry Torokhov wrote:
> > > > v9: 
> > > > 	- Removed the header file and put the definitions into the c file.
> > > > 	- Updated the pwm code and error logs with %pE
> > > 
> > > I believe the %pE is to format an escaped buffer, you probably want to
> > > %pe (lowercase) to print errors. I am also not quite sure if we want to
> > > use it in cases when we have non-pointer error, or we should stick with
> > > %d as most of the kernel does.
> > 
> > compared with %d %pe is easier to understand as it emits "-ETIMEOUT"
> > instead of "-110". And yes, %pE is wrong.
> 
> While I can see that symbolic name instead of a numeric constant might
> be appealing, I do not believe that we want fragments like this with
> endless conversions between integer and pointer errors:
> 
> 	if (haptics->const_op_mode == DA7280_PWM_MODE) {
> 		haptics->pwm_dev = devm_pwm_get(dev, NULL);
> 		if (IS_ERR(haptics->pwm_dev)) {
> 			error = PTR_ERR(haptics->pwm_dev);
> 			if (error != -EPROBE_DEFER)
> 				dev_err(dev, "unable to request PWM: %pE\n",
> 					ERR_PTR(error));
> 			return error;
> 		}
> 
> Maybe we should introduce something like '%de' for the integer error
> case?

I suggested that some time ago with limited success, see
https://lore.kernel.org/lkml/20200129115516.zsvxu56e6h7gheiw@pathway.suse.cz/
.

> In the meantime I would prefer using %d when we have integer
> error. We should not see these error messages anyway ;)

I don't agree. Error messages are supposed to be helpful and I prefer
some casting between error pointer and error int over emitting bare
numbers to the kernel log. (And additionally the uglyness might help to
convince the vsprintf guys that %de might be a good idea after all :-)

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]