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J.F.
Joined: 22 Feb 2004
Posts: 2906
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 Posted: Tue Apr 01, 2008 6:14 am Post subject: Question about setting CPU speed |
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This is mostly aimed at moonlight. One thing I found when I first started messing with the slim was that setting the CPU speed while the ME was active would hang the PSP. Anything I do that uses the ME has to set the speed first, then activate the ME. Deactivating the ME doesn't seem to help. Once it's been activated, that's it for setting the speed. Here's my test:
http://www.mediafire.com/?ysfm14czjjm
Basically, it sets the speed, then uses the ME to do a color cycle on the display, changing the speed at certain points (if enabled). I made it where I could disable the "extra" speed changes to verify the code was working.
One thing in particular this "quirk" affects is the Slim version of the SNES9x emulator - it's hard-coded to run at 333MHz all the time simply because of this issue with the ME. I tried various methods of disabling the ME, but couldn't get the speed to change regardless. It's odd that the quirk even happens in the first place unless there's a bug in the Slim hardware. The Phat certainly allows the CPU to change speed while the ME is active.
I appreciate any help anyone can provide on this. Thanks. |
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crazyc
Joined: 17 Jun 2005
Posts: 410
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| Posted: Tue Apr 01, 2008 7:25 am Post subject: |
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| I don't have a slim, but I documented how to set the pll clock directly on ther fat here, so if you aren't afraid of making it explode, messing with those registers might be a way to test what's wrong. |
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Wally
Joined: 26 Sep 2005
Posts: 672
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| Posted: Tue Apr 01, 2008 7:43 am Post subject: |
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Wouldn't the PSP just detect an abnormal temperature and shut off?
Wally |
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crazyc
Joined: 17 Jun 2005
Posts: 410
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| Posted: Tue Apr 01, 2008 9:40 am Post subject: |
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| Wally4000 wrote: | Wouldn't the PSP just detect an abnormal temperature and shut off?
Wally |
Perhaps if you set the clock to higher then 333Mhz (I momentarily set mine to 370 by accident and it didn't shut off, but I'm not going to sacrifice my psp for more testing), but that's not what JF wants to do. |
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J.F.
Joined: 22 Feb 2004
Posts: 2906
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| Posted: Tue Apr 01, 2008 12:28 pm Post subject: |
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| crazyc wrote: | | I don't have a slim, but I documented how to set the pll clock directly on ther fat here, so if you aren't afraid of making it explode, messing with those registers might be a way to test what's wrong. |
Well, if we can't work around the "bug" in the official code, I'll try your info out and see what happens.
I have seen at least one article on overclocking the PSP. Someone did indeed burn out two PSPs trying to run them at almost 400 MHz. Supposedly, they would boot at about 350 to 360 MHz, but crashed in various programs, and wouldn't boot at more than 380 MHz and failed to start after that.
Given that, I have no plans to try anything more than the official 333MHz. :) |
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moonlight
Joined: 26 Oct 2005
Posts: 567
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| Posted: Tue Apr 01, 2008 4:47 pm Post subject: |
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I'll check if it could be a software problem, but it sounds more like a hardware failure.
This remembers me of the 333 Mhz and wlan issue, scePowerWlanActivate failed when having 333 Mhz but wlan would still work if nullifying the negative result of the function :) I don't think this time the fix would be something so trivial. |
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sakya
Joined: 28 Apr 2006
Posts: 190
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| Posted: Tue Apr 01, 2008 7:02 pm Post subject: |
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Hi! :)
| moonlight wrote: | | I'll check if it could be a software problem, but it sounds more like a hardware failure. |
Sorry to bother but...can you please also tell me if the changed limit of CPU and BUS clock is due to hardware changes (and sony didn't bother to make difference from fat and slim)?
On a CF<=3.52 I can set the CPU from 10Mhz to 333 while on CF>=3.71 (maybe >=3.60, never tried 3.60) the lower limit raised to 19.
This is not a big problem, but with BUS the situation changed a lot.
On a CF<=3.52 I can set the BUS from 54Mhz to 166Mhz (almost every value worked 54,55,56,57...) but now on CF>=3.71 the lower limit raised to 95 (!!!) and cannot set many values (from 95 to 111 there are no usable values, for example).
Is there a way I can set the BUS clock at 54Mhz on a CF>=3.71?
Many thanks. :)
Ciaooo
Sakya |
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J.F.
Joined: 22 Feb 2004
Posts: 2906
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| Posted: Tue Apr 01, 2008 7:09 pm Post subject: |
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| moonlight wrote: | I'll check if it could be a software problem, but it sounds more like a hardware failure.
This remembers me of the 333 Mhz and wlan issue, scePowerWlanActivate failed when having 333 Mhz but wlan would still work if nullifying the negative result of the function :) I don't think this time the fix would be something so trivial. |
You can change the speed as much as you like if the ME is not active. Quiting a program to the XMB is enough of a reset of the ME to allow it. So even if you don't find a way to set the speed while the ME is active, at least finding how the ME is turned off should be enough - we can then just shut down the ME, change the speed, then turn it back on. That's what I was attempting to do in the test code... experimenting with reseting the ME, or turning off its bus clock... that sort of thing. |
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