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Date: Thu, 6 Jun 2024 12:18:43 +0100
From: Liviu Dudau <liviu.dudau@arm.com>
To: Jani Nikula <jani.nikula@linux.intel.com>
Cc: pengfuyuan <pengfuyuan@kylinos.cn>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	k2ci <kernel-bot@kylinos.cn>
Subject: Re: [PATCH] arm/komeda: Compile DEFINE_SHOW_ATTRIBUTE() only when
 CONFIG_DEBUG_FS is enabled
Message-ID: <ZmGbE3g_OFuowEgF@e110455-lin.cambridge.arm.com>
References: <20240606075846.1307007-1-pengfuyuan@kylinos.cn>
 <87ed9abhxx.fsf@intel.com>
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In-Reply-To: <87ed9abhxx.fsf@intel.com>

On Thu, Jun 06, 2024 at 11:20:58AM +0300, Jani Nikula wrote:
> On Thu, 06 Jun 2024, pengfuyuan <pengfuyuan@kylinos.cn> wrote:
> > We do not call komeda_debugfs_init() and the debugfs core function
> > declaration if CONFIG_DEBUG_FS is not defined, but we should not
> > compile it either because the debugfs core function declaration is
> > not included.
> >
> > Reported-by: k2ci <kernel-bot@kylinos.cn>

Can we see what the bot reported?

> > Signed-off-by: pengfuyuan <pengfuyuan@kylinos.cn>
> 
> An interesting alternative might actually be to remove *all* the
> CONFIG_DEBUG_FS conditional compilation from the file. Since the debugfs
> functions have no-op stubs for CONFIG_DEBUG_FS=n, the compiler will
> optimize the rest away, because they're no longer referenced. (For the
> same reason, I don't think this patch has an impact for code size.)
> 
> The upside for removing conditional compilation is that you'll actually
> do build testing for both CONFIG_DEBUG_FS config values. Assuming most
> developers have it enabled, there's not a lot of testing going on for
> CONFIG_DEBUG_FS=n, and you might introduce build failures with the
> conditional compilation.
> 
> Of course, up to Liviu to decide.

Yeah, I quite like the idea of removing the conditional compilation from
the file entirely.

Pengfuyuan, do you mind sending a new patch removing all the CONFIG_DEBUG_FS
from the file, rather than moving things around?

Best regards,
Liviu

> 
> 
> BR,
> Jani.
> 
> 
> > ---
> >  drivers/gpu/drm/arm/display/komeda/komeda_dev.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_dev.c b/drivers/gpu/drm/arm/display/komeda/komeda_dev.c
> > index 14ee79becacb..7ada8e6f407c 100644
> > --- a/drivers/gpu/drm/arm/display/komeda/komeda_dev.c
> > +++ b/drivers/gpu/drm/arm/display/komeda/komeda_dev.c
> > @@ -21,6 +21,7 @@
> >  
> >  #include "komeda_dev.h"
> >  
> > +#ifdef CONFIG_DEBUG_FS
> >  static int komeda_register_show(struct seq_file *sf, void *x)
> >  {
> >  	struct komeda_dev *mdev = sf->private;
> > @@ -43,7 +44,6 @@ static int komeda_register_show(struct seq_file *sf, void *x)
> >  
> >  DEFINE_SHOW_ATTRIBUTE(komeda_register);
> >  
> > -#ifdef CONFIG_DEBUG_FS
> >  static void komeda_debugfs_init(struct komeda_dev *mdev)
> >  {
> >  	if (!debugfs_initialized())
> 
> -- 
> Jani Nikula, Intel

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯