[PATCH RESEND v2 06/25] drm/fb_helper: Create a wrapper for remove_conflicting_framebuffers

[Archit Taneja]

On 07/29/2015 12:19 AM, Daniel Vetter wrote:
> On Tue, Jul 28, 2015 at 08:46:24PM +0200, Daniel Vetter wrote:
>> On Wed, Jul 22, 2015 at 02:58:01PM +0530, Archit Taneja wrote:
>>> Some drm drivers call remove_conflicting_framebuffers. Create a
>>> drm_fb_helper function that wraps around these calls.
>>>
>>> This is part of an effort to prevent drm drivers from calling fbdev
>>> functions directly, in order to make fbdev emulation a top level drm
>>> option.
>>>
>>> v2:
>>> - Added kerneldocs
>>> - Follow the drm way of aligning of arguments in func definitions
>>>
>>> Signed-off-by: Archit Taneja <architt at codeaurora.org>
>>> ---
>>>   drivers/gpu/drm/drm_fb_helper.c | 15 +++++++++++++++
>>>   include/drm/drm_fb_helper.h     |  4 ++++
>>>   2 files changed, 19 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
>>> index 9620aa5..86e4e2c 100644
>>> --- a/drivers/gpu/drm/drm_fb_helper.c
>>> +++ b/drivers/gpu/drm/drm_fb_helper.c
>>> @@ -894,6 +894,21 @@ void drm_fb_helper_set_suspend(struct drm_fb_helper *fb_helper, int state)
>>>   }
>>>   EXPORT_SYMBOL(drm_fb_helper_set_suspend);
>>>
>>> +/**
>>> + * drm_fb_helper_remove_conflicting_framebuffers - wrapper around
>>> + *						remove_conflicting_framebuffers
>>> + * @fb_helper: driver-allocated fbdev helper
>>> + *
>>> + * A wrapper around remove_conflicting_framebuffers implemented by fbdev core
>>> + */
>>> +int drm_fb_helper_remove_conflicting_framebuffers(struct apertures_struct *a,
>>> +						  const char *name,
>>> +						  bool primary)
>>> +{
>>> +	return remove_conflicting_framebuffers(a, name, primary);
>>> +}
>>> +EXPORT_SYMBOL(drm_fb_helper_remove_conflicting_framebuffers);
>>
>> Chris Wilson reported on irc that if he builds with I915_FBDEV=n then
>> there's a missing symbol problem here because i915 wants to kick out other
>> framebuffers (well we have to for correctness) even when fbdev emulation
>> is disabled. If you look at i915_dma.c you'll see that the call to
>> remove_conflicting_framebuffers is conditional upon CONFIG_FB and not
>> CONFIG_I915_FBDEV.
>>
>> I think the proper solution here would be to provide a static inline
>> helper for remove_conflicting_framebuffer itself when CONFIG_FB=n, since a
>> all drivers who call this still want to call this even when fbdev
>> emulation is disabled.
>>
>> Plan B would be to move this into core drm and make the static inline one
>> selected for CONFIG_FB=n. If you do that then maybe also rename it to
>> drm_remove_conflicting_framebuffer since this really is only tangetial to
>> fbdev emulation.
>>
>> Anyway current patch unfortunately won't work since we really must remove
>> other framebuffers even in the FB=y, I915_FBDEV=n case. So I dropped it
>> from drm-misc for now. Unfortunately that means all the driver conversions
>> won't apply anymore either :(
>
> Ok I didn't have to drop all of the driver specific patches since all the
> arm ones don't have calls to remove_conflicting_framebuffers.

I can re-spin the x86 ones and make them stick to the original 
remove_conflicting_framebuffers call. This way we can at least use the
other helpers.

Archit

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