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1.50 Kernel - Capable of suspend(/standby?), or not?

 
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EmrldDrgn



Joined: 20 May 2009
Posts: 4
PostPosted: Wed May 20, 2009 5:58 am    Post subject: 1.50 Kernel - Capable of suspend(/standby?), or not? Reply with quote
I know a lot of older 1.50 homebrew doesn't support sleep mode, but some people seem to think this is because the 1.50 kernel can't do sleep mode. Is this true? I just wrote a test program to see if it would work, and it seemed to, but one test case is hardly significant, and the program was very simple, so it could have something to do with that.

Can someone confirm/deny that the 1.50 kernel is capable of the suspend (standby?) function?

Also, what's the difference between standby and suspend?
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Art



Joined: 09 Nov 2005
Posts: 647
PostPosted: Wed May 20, 2009 8:55 am    Post subject: Reply with quote
Suspend preserves RAM, and can restart where you left off like a
quick flick of the power switch, where standby is like holding the power switch for a few seconds and causes a restart.
1.50 kernel can do both.
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If not actually, then potentially.
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J.F.



Joined: 22 Feb 2004
Posts: 2906
PostPosted: Wed May 20, 2009 12:45 pm    Post subject: Reply with quote
One problem with suspend is that it closes all files and terminates connections. The problem is that when you when the app is resumed, none of that is reversed... files are still closed and connections are still terminated. You need to add callbacks to the power manager to do some work to clean things up and restart them on suspend/resume. You can see what I did in Basilisk II to deal with suspend/resume. Many people are hard pressed to port an app to the PSP in the first place - they don't know enough about the operation of the app to handle suspend.

Another problem is a bit more esoteric. If you use the MediaEngine, suspend will hang the PSP. That's why some apps like SNESTYL ME disable suspend while running.
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willow :--)



Joined: 13 Jan 2007
Posts: 126
PostPosted: Wed May 20, 2009 2:25 pm    Post subject: Reply with quote
J.F. wrote:

If you use the MediaEngine, suspend will hang the PSP.

Isn't there a workaround for that? The MediaEngine is used in the XMB when playing mp3s, correct?
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J.F.



Joined: 22 Feb 2004
Posts: 2906
PostPosted: Wed May 20, 2009 8:16 pm    Post subject: Reply with quote
willow :--) wrote:
J.F. wrote:

If you use the MediaEngine, suspend will hang the PSP.

Isn't there a workaround for that? The MediaEngine is used in the XMB when playing mp3s, correct?


I'm sure Sony knows how to do it, but the code we use to use the ME isn't good enough. It's almost certainly related to the fact that changing the CPU clock after starting the ME also hangs the PSP. The ME doesn't even need to be running - even if you disable the ME, changing the clock still hangs the PSP. It doesn't go back to normal operation until you exit back to the XMB.

It would be nice to know more about the "official" interface to the ME. The level that is used currently to run stuff on the ME doesn't play nice with the firmware.
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Torch



Joined: 28 May 2008
Posts: 842
PostPosted: Wed May 20, 2009 10:56 pm    Post subject: Reply with quote
Couldn't someone reverse a game and see how it handles suspend with the ME? Most games use the ME for videos and if you suspend it it usually restarts the video from the beginning on resume. But thats probably just a limitation of Sony's video decoder interface to the ME. We would only be interested in the suspend resume bit.. And regarding the videos, Burnout Dominator doesn't restart the video from the beginning, but resumes playing so that might be a better target. to learn about ME video lib.
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EmrldDrgn



Joined: 20 May 2009
Posts: 4
PostPosted: Fri May 22, 2009 1:34 pm    Post subject: Reply with quote
Is the ME crash behavior true for non-1.50 kernels too? I suppose it would have to be...
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J.F.



Joined: 22 Feb 2004
Posts: 2906
PostPosted: Fri May 22, 2009 2:13 pm    Post subject: Reply with quote
EmrldDrgn wrote:
Is the ME crash behavior true for non-1.50 kernels too? I suppose it would have to be...


Actually, I don't know if it's true for 1.50. I first noticed it at 3.71. It could be the ME is fine under 1.50. Anything > 3.60 seems affected.
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