[PATCH weston] clients/dmabuf-intel: use three buffers

[Pekka Paalanen]

On Mon, 13 Jun 2016 08:14:12 -0500
Yong Bakos <junk at humanoriented.com> wrote:

> On Jun 13, 2016, at 6:17 AM, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> > 
> > From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> > 
> > Use three buffers like simple-dmabuf-v4l instead of just two.
> > 
> > This is required, because when a frame callback arrives, the just
> > committed buffer is only on its way to the screen, while the previous
> > buffer is still being scanned out. It will take for the page flip to
> > complete, before the previous buffer is release. However, we want to be
> > able to repaint already at the frame callback, so three buffers can be
> > necessary.
> > 
> > This patch fixes weston-simple-dmabuf-intel to not abort with "Both
> > buffers busy at redraw()." when hardware overlays are used and the
> > surface gets directly scanned out.
> > 
> > Signed-off-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>  
> 
> While I could not test this, it's a straightforward change, and it
> does touch all cases in simple-dmabuf-intel.
> 
> Reviewed-by: Yong Bakos <ybakos at humanoriented.com>

Hi,

oh yeah, testing this requires not only Intel hardware, but also
running with the DRM-backend/GL-renderer and using Mod+Shift+Space, 'v'
to force-enable hardware overlays, which also halves the compositor
framerate.

Using Mod+Shift+Space, 's' you can tint all GL-rendered surfaces green,
so that hardware overlays stand out as normally colored.

If you want to play with hardware overlays, there is also
weston-simple-egl with the -o option to make it opaque.


Thanks,
pq

> > ---
> > clients/simple-dmabuf-intel.c | 23 +++++++++++------------
> > 1 file changed, 11 insertions(+), 12 deletions(-)
> > 
> > diff --git a/clients/simple-dmabuf-intel.c b/clients/simple-dmabuf-intel.c
> > index 2ac2200..2c8eb24 100644
> > --- a/clients/simple-dmabuf-intel.c
> > +++ b/clients/simple-dmabuf-intel.c
> > @@ -74,12 +74,14 @@ struct buffer {
> > 	unsigned long stride;
> > };
> > 
> > +#define NUM_BUFFERS 3
> > +
> > struct window {
> > 	struct display *display;
> > 	int width, height;
> > 	struct wl_surface *surface;
> > 	struct xdg_surface *xdg_surface;
> > -	struct buffer buffers[2];
> > +	struct buffer buffers[NUM_BUFFERS];
> > 	struct buffer *prev_buffer;
> > 	struct wl_callback *callback;
> > };
> > @@ -341,7 +343,7 @@ create_window(struct display *display, int width, int height)
> > 		assert(0);
> > 	}
> > 
> > -	for (i = 0; i < 2; ++i) {
> > +	for (i = 0; i < NUM_BUFFERS; ++i) {
> > 		ret = create_dmabuf_buffer(display, &window->buffers[i],
> > 		                               width, height);
> > 
> > @@ -360,7 +362,7 @@ destroy_window(struct window *window)
> > 	if (window->callback)
> > 		wl_callback_destroy(window->callback);
> > 
> > -	for (i = 0; i < 2; i++) {
> > +	for (i = 0; i < NUM_BUFFERS; i++) {
> > 		if (!window->buffers[i].buffer)
> > 			continue;
> > 
> > @@ -379,16 +381,13 @@ destroy_window(struct window *window)
> > static struct buffer *
> > window_next_buffer(struct window *window)
> > {
> > -	struct buffer *buffer;
> > +	int i;
> > 
> > -	if (!window->buffers[0].busy)
> > -		buffer = &window->buffers[0];
> > -	else if (!window->buffers[1].busy)
> > -		buffer = &window->buffers[1];
> > -	else
> > -		return NULL;
> > +	for (i = 0; i < NUM_BUFFERS; i++)
> > +		if (!window->buffers[i].busy)
> > +			return &window->buffers[i];
> > 
> > -	return buffer;
> > +	return NULL;
> > }
> > 
> > static const struct wl_callback_listener frame_listener;
> > @@ -403,7 +402,7 @@ redraw(void *data, struct wl_callback *callback, uint32_t time)
> > 	if (!buffer) {
> > 		fprintf(stderr,
> > 			!callback ? "Failed to create the first buffer.\n" :
> > -			"Both buffers busy at redraw(). Server bug?\n");
> > +			"All buffers busy at redraw(). Server bug?\n");
> > 		abort();
> > 	}
> > 
> > -- 
> > 2.7.3
> > 
> > _______________________________________________
> > wayland-devel mailing list
> > wayland-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/wayland-devel  
> 

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 811 bytes
Desc: OpenPGP digital signature
URL: <https://lists.freedesktop.org/archives/wayland-devel/attachments/20160613/015e8770/attachment.sig>