linux-kernel - Re: [PATCH v1 2/3] gpiolib: Fix debug messaging in gpiod_find_and

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Date:   Tue, 14 Nov 2023 21:18:24 +0000
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Hans de Goede <hdegoede@...hat.com>,
        Ferry Toth <ftoth@...londelft.nl>
Subject: Re: [PATCH v1 2/3] gpiolib: Fix debug messaging in
 gpiod_find_and_request()

On Tue, Nov 14, 2023 at 05:29:59PM +0200, Andy Shevchenko wrote:
> On Thu, Oct 19, 2023 at 12:21:12PM -0700, Dmitry Torokhov wrote:
> > On Thu, Oct 19, 2023 at 08:34:56PM +0300, Andy Shevchenko wrote:
> > > When consolidating GPIO lookups in ACPI code, the debug messaging
> > > had been broken and hence lost a bit of sense. Restore debug
> > > messaging in gpiod_find_and_request() when configuring the GPIO
> > > line via gpiod_configure_flags().
> > 
> > Could you give an example of the before/after messages to show exavtly
> > what is being improved?
> 
> Before your patch:
> 
> [    5.266823] gpio-96 (ACPI:OpRegion): no flags found for ACPI:OpRegion
> [   14.182994] gpio-40 (?): no flags found for gpios
> 
> After your patch:
> 
> [    5.085048] gpio-96 (ACPI:OpRegion): no flags found for ACPI:OpRegion
> [   13.401402] gpio-40 (?): no flags found for (null)
> 
> After this patch:
> 
> [    3.871185] gpio-96 (ACPI:OpRegion): no flags found for ACPI:OpRegion
> [   12.491998] gpio-40 (?): no flags found for gpios
> 
> ...
> 
> Looking at this it's definitely a fix.

If this ("(null)" vs static "gpios" string) is important, can we reduce
the patch to:

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 76e0c38026c3..b868c016a9be 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -4151,7 +4151,7 @@ int gpiod_configure_flags(struct gpio_desc *desc, const char *con_id,
 
 	/* No particular flag request, return here... */
 	if (!(dflags & GPIOD_FLAGS_BIT_DIR_SET)) {
-		gpiod_dbg(desc, "no flags found for %s\n", con_id);
+		gpiod_dbg(desc, "no flags found for %s\n", con_id ?: "gpios");
 		return 0;
 	}
 

instead of plumbing the names through?

Although this (and the original fix patch) are losing information, in
the sense that "(null)" explicitly communicates that caller used
default/NULL conn_id, and not something like "gpios-gpios".

Thanks.

-- 
Dmitry