[PATCH 02/15] drm: Add drm_device->drm_fb_helper_private pointer

[Noralf Trønnes]

Den 20.10.2017 15.52, skrev Ville Syrjälä:
> On Fri, Oct 20, 2017 at 01:02:00AM +0200, Noralf Trønnes wrote:
>> drm_fb_helper is *the* way of doing fbdev emulation so add a pointer to
>> struct drm_device. This makes it possible to add callback helpers for
>> .last_close and .output_poll_changed further reducing fbdev emulation
>> footprint in drivers. The pointer is set by drm_fb_helper_init() and
>> cleared by drm_fb_helper_fini().
>>
>> Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
>> ---
>>
>> This patch was initially part of the patchset: drm/tinydrm: Use vmalloc BO
>> Changes since previous version:
>> - Change member name: fbdev -> drm_fb_helper_private
>> - Expand docs
>> - Set and clear pointer in drm_fb_helper_init/fini()
>>
>>   drivers/gpu/drm/drm_fb_helper.c | 13 +++++++++++--
>>   include/drm/drm_device.h        |  9 +++++++++
>>   2 files changed, 20 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
>> index 954cdd48de92..c07b7af8de4c 100644
>> --- a/drivers/gpu/drm/drm_fb_helper.c
>> +++ b/drivers/gpu/drm/drm_fb_helper.c
>> @@ -799,8 +799,10 @@ int drm_fb_helper_init(struct drm_device *dev,
>>   	struct drm_mode_config *config = &dev->mode_config;
>>   	int i;
>>   
>> -	if (!drm_fbdev_emulation)
>> +	if (!drm_fbdev_emulation) {
>> +		dev->drm_fb_helper_private = fb_helper;
>>   		return 0;
>> +	}
>>   
>>   	if (!max_conn_count)
>>   		return -EINVAL;
>> @@ -835,6 +837,8 @@ int drm_fb_helper_init(struct drm_device *dev,
>>   		i++;
>>   	}
>>   
>> +	dev->drm_fb_helper_private = fb_helper;
>> +
>>   	return 0;
>>   out_free:
>>   	drm_fb_helper_crtc_free(fb_helper);
>> @@ -913,7 +917,12 @@ void drm_fb_helper_fini(struct drm_fb_helper *fb_helper)
>>   {
>>   	struct fb_info *info;
>>   
>> -	if (!drm_fbdev_emulation || !fb_helper)
>> +	if (!fb_helper)
>> +		return;
>> +
>> +	fb_helper->dev->drm_fb_helper_private = NULL;
>> +
>> +	if (!drm_fbdev_emulation)
>>   		return;
>>   
>>   	cancel_work_sync(&fb_helper->resume_work);
>> diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
>> index e21af87a2f3c..6b26262658ae 100644
>> --- a/include/drm/drm_device.h
>> +++ b/include/drm/drm_device.h
>> @@ -17,6 +17,7 @@ struct drm_vblank_crtc;
>>   struct drm_sg_mem;
>>   struct drm_local_map;
>>   struct drm_vma_offset_manager;
>> +struct drm_fb_helper;
>>   
>>   struct inode;
>>   
>> @@ -185,6 +186,14 @@ struct drm_device {
>>   	struct drm_vma_offset_manager *vma_offset_manager;
>>   	/*@} */
>>   	int switch_power_state;
>> +
>> +	/**
>> +	 * @drm_fb_helper_private:
>> +	 *
>> +	 * Pointer to the fbdev emulation structure.
>> +	 * Set by drm_fb_helper_init() and cleared by drm_fb_helper_fini().
>> +	 */
>> +	struct drm_fb_helper *drm_fb_helper_private;
> Just 'fb_helper' maybe? Not sure what the _private here is supposed to
> mean, and drm_ seems very much redundant.

I first called it fbdev, Daniel suggested fbdev_helper_private, then I
took it all the way and called it drm_fb_helper_private. I believe the
_private part is an indication that this is not part of the core, but a
helper, like drm_plane->helper_private.

fb_helper is the common variable name used in drm_fb_helper (which
really should have been called drm_fbdev_helper imo).

These are the names that drivers use:

     struct amdgpu_fbdev *rfbdev;
     struct drm_fb_helper    *fbdev;
     struct ast_fbdev *fbdev;
     struct drm_fb_helper fb.helper;
     struct cirrus_fbdev        *gfbdev;
     struct drm_fb_helper    fb_helper;
     struct drm_fb_helper *fb_helper;
     void *fbdev;
     struct hibmc_fbdev *fbdev;
     struct mga_fbdev *mfbdev;
     struct drm_fb_helper *fbdev;
     struct nouveau_fbdev *fbcon;
     struct drm_fb_helper *fbdev;
     struct qxl_fbdev *qfbdev;
     struct radeon_fbdev *rfbdev;
     struct drm_fb_helper fbdev_helper;
     struct tegra_fbdev *fbdev;
     struct udl_fbdev *fbdev;
     struct virtio_gpu_fbdev *vgfbdev;
     struct vbox_fbdev *fbdev;

Noralf.

>>   };
>>   
>>   #endif
>> -- 
>> 2.14.2
>>
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