linux-kernel - Re: [PATCH 1/3] drm/panic: Add drm_panic_is

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Message-ID: <34305c58-38a6-4b5a-9777-69833aefa003@redhat.com>
Date: Thu, 18 Jul 2024 09:04:04 +0200
From: Jocelyn Falempe <jfalempe@...hat.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Helge Deller <deller@....de>,
 "Jiri Slaby (SUSE)" <jirislaby@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Geert Uytterhoeven <geert+renesas@...der.be>,
 Javier Martinez Canillas <javierm@...hat.com>,
 Samuel Thibault <samuel.thibault@...-lyon.org>,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 linux-fbdev@...r.kernel.org
Subject: Re: [PATCH 1/3] drm/panic: Add drm_panic_is_enabled()



On 17/07/2024 17:08, Daniel Vetter wrote:
> On Wed, Jul 17, 2024 at 10:48:39AM +0200, Jocelyn Falempe wrote:
>> It allows to check if the drm device supports drm_panic.
>> Prepare the work to have better integration with fbcon and vtconsole.
>>
>> Signed-off-by: Jocelyn Falempe <jfalempe@...hat.com>
>> ---
>>   drivers/gpu/drm/drm_panic.c | 20 ++++++++++++++++++++
>>   include/drm/drm_panic.h     |  2 ++
>>   2 files changed, 22 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
>> index 948aed00595e..d9a25c2d0a65 100644
>> --- a/drivers/gpu/drm/drm_panic.c
>> +++ b/drivers/gpu/drm/drm_panic.c
>> @@ -703,6 +703,26 @@ static void debugfs_register_plane(struct drm_plane *plane, int index)
>>   static void debugfs_register_plane(struct drm_plane *plane, int index) {}
>>   #endif /* CONFIG_DRM_PANIC_DEBUG */
>>   
>> +/**
>> + * drm_panic_is_enabled
>> + * @dev: the drm device that may supports drm_panic
>> + *
>> + * returns true if the drm device supports drm_panic
>> + */
>> +bool drm_panic_is_enabled(struct drm_device *dev)
>> +{
>> +	struct drm_plane *plane;
>> +
>> +	if (!dev->mode_config.num_total_plane)
>> +		return false;
>> +
>> +	drm_for_each_plane(plane, dev)
>> +		if (plane->helper_private && plane->helper_private->get_scanout_buffer)
>> +			return true;
>> +	return false;
>> +}
>> +EXPORT_SYMBOL(drm_panic_is_enabled);
> 
> This feels like overkill since you currently only have one user in the
> fbdev emulation code, but maybe useful in some other places ...
> 
>> +
>>   /**
>>    * drm_panic_register() - Initialize DRM panic for a device
>>    * @dev: the drm device on which the panic screen will be displayed.
>> diff --git a/include/drm/drm_panic.h b/include/drm/drm_panic.h
>> index 73bb3f3d9ed9..c3a358dc3e27 100644
>> --- a/include/drm/drm_panic.h
>> +++ b/include/drm/drm_panic.h
>> @@ -148,11 +148,13 @@ struct drm_scanout_buffer {
>>   
>>   #ifdef CONFIG_DRM_PANIC
>>   
>> +bool drm_panic_is_enabled(struct drm_device *dev);
> 
> Since it's internal only, this should be in
> drivers/gpu/drm/drm_crtc_internal.h and not int he include for drivers.

Yes, that makes sense, drivers won't need that API.

> With that:
> 
> Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch>
> 
>>   void drm_panic_register(struct drm_device *dev);
>>   void drm_panic_unregister(struct drm_device *dev);
> 
> These two are only used in drm.ko. Can you please move them to
> drm_crtc_internal.h too and drop the EXPORT_SYMBOL in a follow-up patch?
> We're trying to limit the exported interface and official headers to
> really only the pieces drivers actually need.

Sure, I'll add this to my next drm_panic series.

> 
> Thanks, Sima
> 
>>   
>>   #else
>>   
>> +bool drm_panic_is_enabled(struct drm_device *dev) {return false; }
>>   static inline void drm_panic_register(struct drm_device *dev) {}
>>   static inline void drm_panic_unregister(struct drm_device *dev) {}
>>   
>> -- 
>> 2.45.2
>>
> 

Best regards,

-- 

Jocelyn