Re: [PATCH v4 1/1] drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC

[Daniel Vetter]

On Thu, Mar 02, 2017 at 08:12:02AM +0100, Daniel Vetter wrote:
> On Tue, Feb 28, 2017 at 04:36:51PM +0100, Maxime Ripard wrote:
> > Implement legacy framebuffer ioctl FBIO_WAITFORVSYNC in the generic
> > framebuffer emulation driver. Legacy framebuffer users like non kms/drm
> > based OpenGL(ES)/EGL implementations may require the ioctl to
> > synchronize drawing or buffer flip for double buffering. It is tested on
> > the i.MX6.
> > 
> > Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
> > Tested-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> 
> Pushed to drm-misc, thanks.

I forgot to add Dave's irc ack to the commit patch, but for the record I
discussed it with him and he's not enthuastic, but ok.
-Daniel

> -Daniel
> 
> > ---
> >  drivers/gpu/drm/drm_fb_helper.c | 68 ++++++++++++++++++++++++++++++++++-
> >  include/drm/drm_fb_helper.h     | 12 +++++-
> >  2 files changed, 79 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> > index c6de87abaca8..8ac8716c023a 100644
> > --- a/drivers/gpu/drm/drm_fb_helper.c
> > +++ b/drivers/gpu/drm/drm_fb_helper.c
> > @@ -1240,6 +1240,74 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
> >  EXPORT_SYMBOL(drm_fb_helper_setcmap);
> >  
> >  /**
> > + * drm_fb_helper_ioctl - legacy ioctl implementation
> > + * @info: fbdev registered by the helper
> > + * @cmd: ioctl command
> > + * @arg: ioctl argument
> > + *
> > + * A helper to implement the standard fbdev ioctl. Only
> > + * FBIO_WAITFORVSYNC is implemented for now.
> > + */
> > +int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
> > +			unsigned long arg)
> > +{
> > +	struct drm_fb_helper *fb_helper = info->par;
> > +	struct drm_device *dev = fb_helper->dev;
> > +	struct drm_mode_set *mode_set;
> > +	struct drm_crtc *crtc;
> > +	int ret = 0;
> > +
> > +	mutex_lock(&dev->mode_config.mutex);
> > +	if (!drm_fb_helper_is_bound(fb_helper)) {
> > +		ret = -EBUSY;
> > +		goto unlock;
> > +	}
> > +
> > +	switch (cmd) {
> > +	case FBIO_WAITFORVSYNC:
> > +		/*
> > +		 * Only consider the first CRTC.
> > +		 *
> > +		 * This ioctl is supposed to take the CRTC number as
> > +		 * an argument, but in fbdev times, what that number
> > +		 * was supposed to be was quite unclear, different
> > +		 * drivers were passing that argument differently
> > +		 * (some by reference, some by value), and most of the
> > +		 * userspace applications were just hardcoding 0 as an
> > +		 * argument.
> > +		 *
> > +		 * The first CRTC should be the integrated panel on
> > +		 * most drivers, so this is the best choice we can
> > +		 * make. If we're not smart enough here, one should
> > +		 * just consider switch the userspace to KMS.
> > +		 */
> > +		mode_set = &fb_helper->crtc_info[0].mode_set;
> > +		crtc = mode_set->crtc;
> > +
> > +		/*
> > +		 * Only wait for a vblank event if the CRTC is
> > +		 * enabled, otherwise just don't do anythintg,
> > +		 * not even report an error.
> > +		 */
> > +		ret = drm_crtc_vblank_get(crtc);
> > +		if (!ret) {
> > +			drm_crtc_wait_one_vblank(crtc);
> > +			drm_crtc_vblank_put(crtc);
> > +		}
> > +
> > +		ret = 0;
> > +		goto unlock;
> > +	default:
> > +		ret = -ENOTTY;
> > +	}
> > +
> > +unlock:
> > +	mutex_unlock(&dev->mode_config.mutex);
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL(drm_fb_helper_ioctl);
> > +
> > +/**
> >   * drm_fb_helper_check_var - implementation for ->fb_check_var
> >   * @var: screeninfo to check
> >   * @info: fbdev registered by the helper
> > diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> > index 975deedd593e..2891888c6e41 100644
> > --- a/include/drm/drm_fb_helper.h
> > +++ b/include/drm/drm_fb_helper.h
> > @@ -230,7 +230,8 @@ struct drm_fb_helper {
> >  	.fb_blank	= drm_fb_helper_blank, \
> >  	.fb_pan_display	= drm_fb_helper_pan_display, \
> >  	.fb_debug_enter = drm_fb_helper_debug_enter, \
> > -	.fb_debug_leave = drm_fb_helper_debug_leave
> > +	.fb_debug_leave = drm_fb_helper_debug_leave, \
> > +	.fb_ioctl	= drm_fb_helper_ioctl
> >  
> >  #ifdef CONFIG_DRM_FBDEV_EMULATION
> >  void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper,
> > @@ -286,6 +287,9 @@ void drm_fb_helper_set_suspend_unlocked(struct drm_fb_helper *fb_helper,
> >  
> >  int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info);
> >  
> > +int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
> > +			unsigned long arg);
> > +
> >  int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper);
> >  int drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel);
> >  int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper);
> > @@ -377,6 +381,12 @@ static inline int drm_fb_helper_setcmap(struct fb_cmap *cmap,
> >  	return 0;
> >  }
> >  
> > +static inline int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
> > +				      unsigned long arg)
> > +{
> > +	return 0;
> > +}
> > +
> >  static inline void drm_fb_helper_unlink_fbi(struct drm_fb_helper *fb_helper)
> >  {
> >  }
> > -- 
> > git-series 0.8.11
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch