(In reply to comment #0)
> System Environment:
> --------------------------
> wayland: (master) ab3b5cd71ce6dd1a532d9c1fecabb1a6e9d1a055
> libdrm: (master) 23eeb7e1e45417a5a84f826286dd982dba440cd3
> macros: (master) 52ef6f666a4fb46b693c81dc7a44612e6b78239d
> glproto: (master) 29d5b553b30755a25300c30b67d39b37c9a76466
> dri2proto: (master) 7fd18b15646a62bd82a4eb0eca60a34c1731813d
> xproto: (master) ab1fba1a0967ac2289909c3f1a643f876a5dd393
> libX11: (master) 2ca641c3a506dcbee97e279b67990d5387389f36
> mesa: (master) 3dd7b53178cb085a1ff3d87844fa51487f8892fc
> kbproto: (master) b0f7912512091ea58dfaf8dffb2a658a6afeb96d
> libxkbcommon: (master) 1ab058bbb345245088f54315227fe0cf52ae54ed
> pixman: (master) 4fc586c3df9a53cc1406891e751a6eed3d7da400
> cairo: (master) da8841cc5ea0b45daba6b91227a2b7058a0120b7
> weston: (master) 31f9d0e8de4f788aaf35fb8072dc290da19b097a
> 
> Bug detailed description:
> -------------------------
> When run the wayland client demo 'screenshot' in drm backend, it can't get
> anything on screen but only a black screen in the picture it takes. This is
> tested on SandyBridge platform. It works well in x11 backend. 
> 
> Reproduce steps:
> -------------------------
> 1. start x
> 2. start weston
> 3. start demo screenshot
> 4. check the picture it takes

To reproduce it should _not_ start X, and just start weston on the terminal.

I'm seeing the same thing with nouveau, and wayland 0.85.

It can't be reproduced with:

Arch: i386
Libdrm: (master) 2.4.33-12-g292da616fe1f936ca78a3fa8e1b1b19883e343b6
Wayland: (master)677c5180e67be18b7a0867fafb7f205b57a6e9ff
Mesa: (master)35f2fb70d3826df70fa2f53af05339137cddefc8
Xserver: (master)xorg-server-1.12.0-66-g80fefc42f5e67e6b4a4b440d8991bee7e5f38359
Xf86_video_intel: (master)2.18.0-212-gaf4a6e8cb52ace594934446e6d8a7aaa1945a9b0
Cairo: (master)4f125a1bd069095f3a97f009e7d7af2681353fb1
Cairo_gl: (master)4f125a1bd069095f3a97f009e7d7af2681353fb1
Xkbcommon: (master)3d672fcfea6b823db4793b9ad1c3aadc4b547a08
Weston: (master)e4faa2ab051aca454f3952f458dac42491e54954
Kernel_unstable: (drm-intel-next-queued)fc6826d1dcd65f3d1e9a5377678882e4e08f02be

>
> --- Comment #3 from ZhaoShengyan <shengyanx.zhao@intel.com> 2012-04-18
> 22:01:10 PDT ---
> It can't be reproduced with:
>

Did you mean "can" be reproduced with?


>
> Arch: i386
> Libdrm: (master) 2.4.33-12-g292da616fe1f936ca78a3fa8e1b1b19883e343b6
> Wayland: (master)677c5180e67be18b7a0867fafb7f205b57a6e9ff
> Mesa: (master)35f2fb70d3826df70fa2f53af05339137cddefc8
> Xserver:
> (master)xorg-server-1.12.0-66-g80fefc42f5e67e6b4a4b440d8991bee7e5f38359
> Xf86_video_intel:
> (master)2.18.0-212-gaf4a6e8cb52ace594934446e6d8a7aaa1945a9b0
> Cairo: (master)4f125a1bd069095f3a97f009e7d7af2681353fb1
> Cairo_gl: (master)4f125a1bd069095f3a97f009e7d7af2681353fb1
> Xkbcommon: (master)3d672fcfea6b823db4793b9ad1c3aadc4b547a08
> Weston: (master)e4faa2ab051aca454f3952f458dac42491e54954
> Kernel_unstable:
> (drm-intel-next-queued)fc6826d1dcd65f3d1e9a5377678882e4e08f02be
>
>
The reason screenshot is buggy is because it shoots the back buffer at a
time when it's contents
are not guaranteed. It needs a bit of rework to read the pixels at the
right time - after the scene
is rendered to the back buffer, right before swapping buffers.

(In reply to comment #4)
> >
> > --- Comment #3 from ZhaoShengyan <shengyanx.zhao@intel.com> 2012-04-18
> > 22:01:10 PDT ---
> > It can't be reproduced with:
> >
> Did you mean "can" be reproduced with?
> >
> > Arch: i386
> > Libdrm: (master) 2.4.33-12-g292da616fe1f936ca78a3fa8e1b1b19883e343b6
> > Wayland: (master)677c5180e67be18b7a0867fafb7f205b57a6e9ff
> > Mesa: (master)35f2fb70d3826df70fa2f53af05339137cddefc8
> > Xserver:
> > (master)xorg-server-1.12.0-66-g80fefc42f5e67e6b4a4b440d8991bee7e5f38359
> > Xf86_video_intel:
> > (master)2.18.0-212-gaf4a6e8cb52ace594934446e6d8a7aaa1945a9b0
> > Cairo: (master)4f125a1bd069095f3a97f009e7d7af2681353fb1
> > Cairo_gl: (master)4f125a1bd069095f3a97f009e7d7af2681353fb1
> > Xkbcommon: (master)3d672fcfea6b823db4793b9ad1c3aadc4b547a08
> > Weston: (master)e4faa2ab051aca454f3952f458dac42491e54954
> > Kernel_unstable:
> > (drm-intel-next-queued)fc6826d1dcd65f3d1e9a5377678882e4e08f02be
> >
> >
> The reason screenshot is buggy is because it shoots the back buffer at a
> time when it's contents
> are not guaranteed. It needs a bit of rework to read the pixels at the
> right time - after the scene
> is rendered to the back buffer, right before swapping buffers.

So you mean, it's not fixed yet. We need to run many times of screenshot,and some of them may not be correct.

>
>
> So you mean, it's not fixed yet. We need to run many times of
> screenshot,and
> some of them may not be correct.
>

You can try the patches I have here, on top of master
https://github.com/soreau/weston/commits/screenshot and see if they help.



Scott

Actually, this patch set has been committed to weston master. Hopefully this will fix the problem.

http://cgit.freedesktop.org/wayland/weston/commit/?id=062be7ec93bc658f0e5ae02fc1b4e5b43f3f100a

The bug has been fixed at:
arch: i386
Libdrm: (master) 2.4.33-15-g754655c795fff1c6267d358e54ad5198aee0cdd6
Wayland: (master)9d37682db32f16eb69a76d21569af6cac0d3d08c
Mesa: (master)1a33c1b2b895566299ec76643659adacc239a3dc
Xserver: (master)xorg-server-1.12.0-105-gd77eb7ee49ef19c2c4c7381d56e9d0f9c3fbc890
Xf86_video_intel: (master)2.18.0-220-g8c58c840b1ba579a5601804fc710c58e1e00213f
Cairo: (master)f736cd144305f7c9147912f6ec081962b3191e3d
Cairo_gl: (master)f736cd144305f7c9147912f6ec081962b3191e3d
Xkbcommon: (master)3d672fcfea6b823db4793b9ad1c3aadc4b547a08
Weston: (master)90c6f1c90e0d43b8d1c2a057a0a2784991de23a4
Kernel_unstable:(drm-intel-next-queued)eea7d92bdb47727dfaf5f148f6ea72e9a1cffaf1
So we mark this bug as fixed. 

Thanks for your attention and efforts and sorry for changing the status so late.

Mark this bug as verified.