On Tue, Feb 21, 2017 at 11:00:59AM +0100, Stefan Lengfeld wrote: > Hi Maxime, > > On Wed, Feb 15, 2017 at 05:19:09PM +0100, Maxime Ripard wrote: > > From: Stefan Christ <s.christ@xxxxxxxxx> > > > > Maybe change the author here. Only the boilerplate code looks my original > patch. The real code is your work ;-) > > > 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. > > > > Code is based on > > https://github.com/Xilinx/linux-xlnx/blob/master/drivers/gpu/drm/xilinx/xilinx_drm_fb.c#L196 > > > > Signed-off-by: Stefan Christ <s.christ@xxxxxxxxx> > > Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> > > --- > > drivers/gpu/drm/drm_fb_helper.c | 63 ++++++++++++++++++++++++++++++++++- > > include/drm/drm_fb_helper.h | 12 +++++- > > 2 files changed, 74 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c > > index c6de87abaca8..15ee9641c725 100644 > > --- a/drivers/gpu/drm/drm_fb_helper.c > > +++ b/drivers/gpu/drm/drm_fb_helper.c > > @@ -1240,6 +1240,69 @@ 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; > > + u32 karg; > > + 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: > > + if (get_user(karg, (__u32 __user *)arg)) { > > + ret = -EFAULT; > > + goto unlock; > > + } > > + > > + if (karg >= fb_helper->crtc_count) { > > + ret = -EINVAL; > > + goto unlock; > > + } > > Ville Syrjälä said [1]: > > FBIO_WAITFORVSYNC takes the crtc as a parmeter, so I'm not sure we want > to do this for all the crtcs. Though what that crtc means for fb is > rather poorly defined. > > Don't think it takes the crtc as a parameter in 'arg'. When you look at the > existing fb_ioctl implementations in the directory drivers/video/fbdev/, the > argument 'arg' is either ignored or must be '0'. Have a look at matroxfb. > > Furthmore most exiting userspace code just passes the value "0" as the > argument. For example DirectFB: > > static const int zero = 0; > [...] > if (ioctl( dfb_fbdev->fd, FBIO_WAITFORVSYNC, &zero )) Again the matrox driver is different. And looks like unichrome might have done something even more exotic with the argument. But I do agree that using this with the kms fbdev implementation could be quite problematic as you can't actually know which crtcs the fb_helper has picked. > > I see two options here: > > 1/ Just wait for the first vsync event on the first enabled crtc. This is > a good approximation for the old framebuffer API. It has no concept of > multiple crtcs with concurrenctly running scan out processes. (Maybe apart > from extra vendor implementations). So if there are really more than one active > crtcs in the system, bad luck with framebuffer API. There will be tearing. > Userspace has to use the new DRM/KMS API. > > 2/ Wait for a single vsync event on all active crtcs as Ville Syrjälä > described here [2] in the optimal implementation. > > Kind regards / Mit freundlichen Grüßen > Stefan Lengfeld > > [1] https://lists.freedesktop.org/archives/dri-devel/2017-February/132617.html > [2] https://lists.freedesktop.org/archives/dri-devel/2017-February/132820.html > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Ville Syrjälä Intel OTC _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
