On Wed, Sep 12, 2012 at 10:23:48AM -0500, Rob Clark wrote: > On Wed, Sep 12, 2012 at 10:12 AM, Ville Syrjälä > <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > On Wed, Sep 12, 2012 at 09:42:27AM -0500, Rob Clark wrote: > >> On Wed, Sep 12, 2012 at 9:34 AM, Ville Syrjälä > >> <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > >> > On Wed, Sep 12, 2012 at 09:28:43AM -0500, Rob Clark wrote: > >> >> On Wed, Sep 12, 2012 at 9:23 AM, Ville Syrjälä > >> >> <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > >> >> > On Wed, Sep 12, 2012 at 07:30:18AM -0500, Rob Clark wrote: > >> >> >> On Wed, Sep 12, 2012 at 3:59 AM, Ville Syrjälä > >> >> >> <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > >> >> >> > On Tue, Sep 11, 2012 at 05:07:49PM -0500, Rob Clark wrote: > >> >> >> >> On Tue, Sep 11, 2012 at 4:15 PM, Ben Widawsky <ben@xxxxxxxxxxxx> wrote: > >> >> >> >> > On Sun, 9 Sep 2012 22:19:59 -0500 > >> >> >> >> > Rob Clark <rob@xxxxxx> wrote: > >> >> >> >> > > >> >> >> >> >> On Sun, Sep 9, 2012 at 10:03 PM, Rob Clark <rob.clark@xxxxxxxxxx> wrote: > >> >> >> >> >> > From: Rob Clark <rob@xxxxxx> > >> >> >> >> >> > > >> >> >> >> >> > This is following a bit the approach that Ville is taking for atomic- > >> >> >> >> >> > modeset, in that it is switching over to using properties for everything. > >> >> >> >> >> > The advantage of this approach is that it makes it easier to add new > >> >> >> >> >> > attributes to set as part of a page-flip (and even opens the option to > >> >> >> >> >> > add new object types). > >> >> >> >> >> > >> >> >> >> >> oh, and for those wondering what the hell this is all about, > >> >> >> >> >> nuclear-pageflip is a pageflip that atomically updates the CRTC layer > >> >> >> >> >> and zero or more attached plane layers, optionally changing various > >> >> >> >> >> properties such as z-order (or even blending modes, etc) atomically. > >> >> >> >> >> It includes the option for a test step so userspace compositor can > >> >> >> >> >> test a proposed configuration (if any properties not marked as > >> >> >> >> >> 'dynamic' are updated). This intended to allow, for example, weston > >> >> >> >> >> compositor to synchronize updates to plane (sprite) layers with CRTC > >> >> >> >> >> layer. > >> >> >> >> >> > >> >> >> >> > > >> >> >> >> > Can we please name this something different? I complained about this in > >> >> >> >> > IRC, but I don't know if you hang around in #intel-gfx. > >> >> >> >> > > >> >> >> >> > Some suggestions: > >> >> >> >> > multiplane pageflip > >> >> >> >> > muliplane atomic pageflip > >> >> >> >> > atomic multiplane pageflip > >> >> >> >> > atomic multiflip > >> >> >> >> > pageflip of atomic and multiplane nature > >> >> >> >> > > >> >> >> >> > Nuclear is not at all descriptive and requires as your response shows > >> >> >> >> > :-) > >> >> >> >> > > >> >> >> >> > >> >> >> >> fair enough.. I was originally calling it atomic-pageflip until > >> >> >> >> someone (I don't remember who) started calling it nuclear-pageflip to > >> >> >> >> differentiate from atomic-modeset. But IMO we could just call the two > >> >> >> >> ioclts atomic-modeset and atomic-pageflip. (Or even modeset2 and > >> >> >> >> pageflip2, but that seems much more boring) > >> >> >> > > >> >> >> > My plan has been to use the same ioctl for both uses. They'll need > >> >> >> > nearly identical handling anyway on the ioctl level. I have something > >> >> >> > semi-working currently, but I need to clean it up a bit before I can > >> >> >> > show it to anyone. > >> >> >> > >> >> >> I do think the atomic-pageflip ioctl really should take the crtc-id.. > >> >> >> so probably should be two ioctls, but nearly identical > >> >> > > >> >> > But then you can't support atomic pageflips across multiple crtcs even > >> >> > if the hardware would allow it. I would hate to add such limitation to > >> >> > the API. I can immediately think of a use case; combining several > >> >> > smaller displays to form a single larger display. > >> >> > > >> >> > With a unified API you could just add some kind of flag that tells the > >> >> > kernel that user space really wants an atomic update, and if the > >> >> > driver/hardware can't do it, it can return an error. > >> >> > >> >> well, that is really only a problem for X11.. and atomic flip across > >> >> multiple crtc's is a potential mess from performance standpoint unless > >> >> your displays are vsync'd lock. > >> > > >> > It won't be truly atomic unless they are vsync locked. But anyways more > >> > buffers can be used to solve the performance problem. But that's a > >> > separate issue and in that case it doesn't really matter whether you > >> > issue separate ioctls for each crtc. > >> > >> that was basically my thinking.. separate ioctls for each crtc. The > >> way my branch works currently, you can do this. A page-flip on crtc > >> #2 won't care that there is still a flip pending on crtc #1. > >> > >> I guess that doesn't strictly guarantee that the two pageflips happen > >> at the exact same time, but unless you have some way to vsync lock the > >> two displays, I don't think that is possible anyways. > > > > Sure you need hardware to keep the pipes in sync. > > > >> So I'm not > >> really sure it is worth over-complicating the ioctl to support two > >> crtc's. The error checking in case a vsync is still pending is much > >> easier in the driver if you know the crtc up-front at the > >> atomic_begin() point. Which is why I prefer to pass the crtc_id as a > >> field in the ioctl. > > > > Doing such checks in atomic_begin() is way too early. Unless you want > > to block/return immediately if there's a pending flip. > > I want to return -EBUSY immediately if there is a pending flip. > > > I want to allow user space to force feed the driver with flips at > > speeds greater than the display refresh. The last frame to finish > > rendering before the vblank is the one that should end up on the > > screen. That way you can do tear-free triple buffering without > > throttling to screen refresh, which is great for benchmarks. It's > > also a nice way to support cases where you want to throttle to a > > 60 Hz display, but you still want to clone the content to say a > > 24 or 30 Hz display. > > Hmm, I still think that userspace should handle this. > > Keeping the existing semantics of -EBUSY when there is a pending flip > makes it easier to implement legacy page_flip on top of the atomic > APIs so the driver doesn't have to care about the difference. I don't > really see the problem w/ userspace dropping frames (depending on egl > swap-interval) if there is still a pending page-flip. It will have to drop the most recent frames, whereas the kernel implementation can drop the older frames, while keeping the latest one. This will help minimize latency. I know OMAP isn't really well suited for this due to the GO bit semantics, but I don't want to punish all hardware through the API design. -- Ville Syrjälä Intel OTC _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
