[1/2] gpio / ACPI: Avoid unnecessary checks in __gpiod_get_index()
diff mbox

Message ID 1829371.gDPkhnsp25@vostro.rjw.lan
State New
Headers show

Commit Message

Rafael J. Wysocki March 10, 2015, 10:08 p.m. UTC
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

If dev is NULL in __gpiod_get_index() and both ACPI and OF are
enabled, it will be checked twice before the code decides to give
up with DT/ACPI lookup, so avoid that.

Also use the observation that ACPI_COMPANION() is much more efficient
than ACPI_HANDLE(), because the latter uses the former and carries out
a check and a pointer dereference on top of it, so replace the
ACPI_HANDLE() check with an ACPI_COMPANION() one which does not
require the additional IS_ENABLED(CONFIG_ACPI) check too.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/gpio/gpiolib.c |   16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)


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Comments

Hanjun Guo March 11, 2015, 1:36 a.m. UTC | #1
On 2015/3/11 6:08, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> If dev is NULL in __gpiod_get_index() and both ACPI and OF are
> enabled, it will be checked twice before the code decides to give
> up with DT/ACPI lookup, so avoid that.
>
> Also use the observation that ACPI_COMPANION() is much more efficient
> than ACPI_HANDLE(), because the latter uses the former and carries out
> a check and a pointer dereference on top of it, so replace the
> ACPI_HANDLE() check with an ACPI_COMPANION() one which does not
> require the additional IS_ENABLED(CONFIG_ACPI) check too.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Quite straight forward to me, for both two patches,

Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>

Thanks
Hanjun

> ---
>  drivers/gpio/gpiolib.c |   16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
>
> Index: linux-pm/drivers/gpio/gpiolib.c
> ===================================================================
> --- linux-pm.orig/drivers/gpio/gpiolib.c
> +++ linux-pm/drivers/gpio/gpiolib.c
> @@ -1865,13 +1865,15 @@ struct gpio_desc *__must_check __gpiod_g
>  
>  	dev_dbg(dev, "GPIO lookup for consumer %s\n", con_id);
>  
> -	/* Using device tree? */
> -	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node) {
> -		dev_dbg(dev, "using device tree for GPIO lookup\n");
> -		desc = of_find_gpio(dev, con_id, idx, &lookupflags);
> -	} else if (IS_ENABLED(CONFIG_ACPI) && dev && ACPI_HANDLE(dev)) {
> -		dev_dbg(dev, "using ACPI for GPIO lookup\n");
> -		desc = acpi_find_gpio(dev, con_id, idx, &lookupflags);
> +	if (dev) {
> +		/* Using device tree? */
> +		if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
> +			dev_dbg(dev, "using device tree for GPIO lookup\n");
> +			desc = of_find_gpio(dev, con_id, idx, &lookupflags);
> +		} else if (ACPI_COMPANION(dev)) {
> +			dev_dbg(dev, "using ACPI for GPIO lookup\n");
> +			desc = acpi_find_gpio(dev, con_id, idx, &lookupflags);
> +		}
>  	}
>  
>  	/*
>
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>
> .
>


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Mika Westerberg March 11, 2015, 8:43 a.m. UTC | #2
On Tue, Mar 10, 2015 at 11:08:57PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> If dev is NULL in __gpiod_get_index() and both ACPI and OF are
> enabled, it will be checked twice before the code decides to give
> up with DT/ACPI lookup, so avoid that.
> 
> Also use the observation that ACPI_COMPANION() is much more efficient
> than ACPI_HANDLE(), because the latter uses the former and carries out
> a check and a pointer dereference on top of it, so replace the
> ACPI_HANDLE() check with an ACPI_COMPANION() one which does not
> require the additional IS_ENABLED(CONFIG_ACPI) check too.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
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Linus Walleij March 18, 2015, 1:33 a.m. UTC | #3
On Tue, Mar 10, 2015 at 11:08 PM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:

> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> If dev is NULL in __gpiod_get_index() and both ACPI and OF are
> enabled, it will be checked twice before the code decides to give
> up with DT/ACPI lookup, so avoid that.
>
> Also use the observation that ACPI_COMPANION() is much more efficient
> than ACPI_HANDLE(), because the latter uses the former and carries out
> a check and a pointer dereference on top of it, so replace the
> ACPI_HANDLE() check with an ACPI_COMPANION() one which does not
> require the additional IS_ENABLED(CONFIG_ACPI) check too.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Patch applied with review and ACK tags.

Yours,
Linus Walleij
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Patch
diff mbox

Index: linux-pm/drivers/gpio/gpiolib.c
===================================================================
--- linux-pm.orig/drivers/gpio/gpiolib.c
+++ linux-pm/drivers/gpio/gpiolib.c
@@ -1865,13 +1865,15 @@  struct gpio_desc *__must_check __gpiod_g
 
 	dev_dbg(dev, "GPIO lookup for consumer %s\n", con_id);
 
-	/* Using device tree? */
-	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node) {
-		dev_dbg(dev, "using device tree for GPIO lookup\n");
-		desc = of_find_gpio(dev, con_id, idx, &lookupflags);
-	} else if (IS_ENABLED(CONFIG_ACPI) && dev && ACPI_HANDLE(dev)) {
-		dev_dbg(dev, "using ACPI for GPIO lookup\n");
-		desc = acpi_find_gpio(dev, con_id, idx, &lookupflags);
+	if (dev) {
+		/* Using device tree? */
+		if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
+			dev_dbg(dev, "using device tree for GPIO lookup\n");
+			desc = of_find_gpio(dev, con_id, idx, &lookupflags);
+		} else if (ACPI_COMPANION(dev)) {
+			dev_dbg(dev, "using ACPI for GPIO lookup\n");
+			desc = acpi_find_gpio(dev, con_id, idx, &lookupflags);
+		}
 	}
 
 	/*