linux-kernel - Re: [PATCH 26/26] drm/i915/gt: Remove #ifdef guards for PM related functions

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Message-Id: <VZWZKR.3K3MGKLWDLB12@crapouillou.net>
Date:   Mon, 07 Nov 2022 20:59:55 +0000
From:   Paul Cercueil <paul@...pouillou.net>
To:     Rodrigo Vivi <rodrigo.vivi@...el.com>
Cc:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 26/26] drm/i915/gt: Remove #ifdef guards for PM related
 functions

Hi Rodrigo,

Le lun. 7 nov. 2022 à 15:31:49 -0500, Rodrigo Vivi 
<rodrigo.vivi@...el.com> a écrit :
> On Mon, Nov 07, 2022 at 05:55:10PM +0000, Paul Cercueil wrote:
>>  Instead of defining two versions of intel_sysfs_rc6_init(), one for 
>> each
>>  value of CONFIG_PM, add a check on !IS_ENABLED(CONFIG_PM) early in 
>> the
>>  function. This will allow the compiler to automatically drop the 
>> dead
>>  code when CONFIG_PM is disabled, without having to use #ifdef 
>> guards.
> 
> Making the RC6 to depend on the CONFIG_PM is probably an historical
> mistake and probably the right solution is simply to remove that
> dependency.

I don't know anything about i915, so the best I can do is update the 
code without changing the functionality.

Then someone with a better understanding can send a patch to remove the 
check on CONFIG_PM.

Cheers,
-Paul

>> 
>>  This has the advantage of always compiling these functions in,
>>  independently of any Kconfig option. Thanks to that, bugs and other
>>  regressions are subsequently easier to catch.
>> 
>>  Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>>  ---
>>  Cc: Jani Nikula <jani.nikula@...ux.intel.com>
>>  Cc: Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
>>  Cc: Rodrigo Vivi <rodrigo.vivi@...el.com>
>>  Cc: Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
>>  Cc: intel-gfx@...ts.freedesktop.org
>>  ---
>>   drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c | 8 +-------
>>   1 file changed, 1 insertion(+), 7 deletions(-)
>> 
>>  diff --git a/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c 
>> b/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c
>>  index 2b5f05b31187..decf892a4508 100644
>>  --- a/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c
>>  +++ b/drivers/gpu/drm/i915/gt/intel_gt_sysfs_pm.c
>>  @@ -164,7 +164,6 @@ sysfs_gt_attribute_r_func(struct kobject *kobj, 
>> struct attribute *attr,
>>   								 NULL);			\
>>   	INTEL_GT_ATTR_RO(_name)
>> 
>>  -#ifdef CONFIG_PM
>>   static u32 get_residency(struct intel_gt *gt, i915_reg_t reg)
>>   {
>>   	intel_wakeref_t wakeref;
>>  @@ -300,7 +299,7 @@ static void intel_sysfs_rc6_init(struct 
>> intel_gt *gt, struct kobject *kobj)
>>   {
>>   	int ret;
>> 
>>  -	if (!HAS_RC6(gt->i915))
>>  +	if (!IS_ENABLED(CONFIG_PM) || !HAS_RC6(gt->i915))
>>   		return;
>> 
>>   	ret = __intel_gt_sysfs_create_group(kobj, rc6_attr_group);
>>  @@ -329,11 +328,6 @@ static void intel_sysfs_rc6_init(struct 
>> intel_gt *gt, struct kobject *kobj)
>>   				 gt->info.id, ERR_PTR(ret));
>>   	}
>>   }
>>  -#else
>>  -static void intel_sysfs_rc6_init(struct intel_gt *gt, struct 
>> kobject *kobj)
>>  -{
>>  -}
>>  -#endif /* CONFIG_PM */
>> 
>>   static u32 __act_freq_mhz_show(struct intel_gt *gt)
>>   {
>>  --
>>  2.35.1
>>