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

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Message-ID: <60419d31-f467-4277-97da-23c9573af2bf@redhat.com>
Date: Thu, 18 Jul 2024 11:30:05 +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 18/07/2024 09:04, Jocelyn Falempe wrote:
> 
> 
> 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.

I think this also applies to drm_panic_init() and drm_panic_exit(), that 
I introduce in my QR code series:
https://patchwork.freedesktop.org/patch/604890/?series=135944&rev=2
I will move them to drm_crtc_internal.h

> 
>>
>> 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,
>