Set clockspeed for sgx?
- Thread starter mcobit
- Start date
This would be interesting. Maybe even a small increase (<10 MHz) would be possible for some pandoras...
I'm going to look around to see if the n900 people have any experience with that.
I know on some android phones/tablets they have GPU overclocks.
Edit: I don't think it's possible. I haven't found anything, I believe it is locked by the chip itself.
Although the GPU performs much better in benchmarks (+10FPS in Quake 3 at a higher resolution!) at 200 MHz which is what the 1GHz pandora's GPU will be clocked at:
http://www.anandtech...ghly-reviewed/5
I'm going to look around to see if the n900 people have any experience with that.
I know on some android phones/tablets they have GPU overclocks.
Edit: I don't think it's possible. I haven't found anything, I believe it is locked by the chip itself.
Although the GPU performs much better in benchmarks (+10FPS in Quake 3 at a higher resolution!) at 200 MHz which is what the 1GHz pandora's GPU will be clocked at:
http://www.anandtech...ghly-reviewed/5
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Exophase
Nothing good will ever come of Exophase.
According to the OMAP35xx TRM.. SGX_FCLK (what the GPU is clocked at, SGX_ICLK governs its memory interface) is derived either from DPLL4_M2X2_CLK or SGX_L3_FCLK.
As far as I can tell DPLL4_M2X2_CLK is supposed to be setup to 96MHz. SGX_L3_FCLK is set to L3_ICLK with a divider of 1, 2, 3, or 4. SGX_FCLK is then SGX_L3_FCLK with a divider of 3, 4, or 6. L3_ICLK is set to 333MHz and as far as I know not that happy with being changed (afaik Ari64 tried it and it wasn't stable).
So that'd give you the following options (I omitted some that are close to these):
110MHz
96MHz
55.5MHz
41.625MHz
37MHz
27.75MHz
20.8125MHz
18.5MHz
13.875MHz
As for how to actually change it, I don't really know, it obviously involves setting some bits in hardware registers and since some of it messes with PLLs probably a lot more is involved.. the proc interfaces for clocks might already handle some or all of it..
As far as I can tell DPLL4_M2X2_CLK is supposed to be setup to 96MHz. SGX_L3_FCLK is set to L3_ICLK with a divider of 1, 2, 3, or 4. SGX_FCLK is then SGX_L3_FCLK with a divider of 3, 4, or 6. L3_ICLK is set to 333MHz and as far as I know not that happy with being changed (afaik Ari64 tried it and it wasn't stable).
So that'd give you the following options (I omitted some that are close to these):
110MHz
96MHz
55.5MHz
41.625MHz
37MHz
27.75MHz
20.8125MHz
18.5MHz
13.875MHz
As for how to actually change it, I don't really know, it obviously involves setting some bits in hardware registers and since some of it messes with PLLs probably a lot more is involved.. the proc interfaces for clocks might already handle some or all of it..
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Pickle
Mega GP Mania
110 and 55 mhz are the numbers i remember, early in pandora development the sgx was clocked at 55 mhz (until it was fixed).
notaz
Certified Guru
Currently there is a "safe" way to under/overclock it by changing system (L3) clock in latest firmwares:
where X can be any value like:
332 -> 166MHz RAM, 110MHz SGX (default)
300 -> 150MHz RAM, 100MHz SGX
...
DM3730 has this set at 400 for 200MHz for both RAM and SGX (using a new divider 2 that's not in OMAP3). OMAP3 works at this setting too (SGX ends up at 133MHz because 3 is the lowest divider there) but is not stable.
As for changing SGX divider, you have to modify the driver because it overrides the divider before turning on the chip each time.
Code:
sudo /usr/pandora/scripts/op_sysspeed.sh Xwhere X can be any value like:
332 -> 166MHz RAM, 110MHz SGX (default)
300 -> 150MHz RAM, 100MHz SGX
...
DM3730 has this set at 400 for 200MHz for both RAM and SGX (using a new divider 2 that's not in OMAP3). OMAP3 works at this setting too (SGX ends up at 133MHz because 3 is the lowest divider there) but is not stable.
As for changing SGX divider, you have to modify the driver because it overrides the divider before turning on the chip each time.
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Exophase
Nothing good will ever come of Exophase.
Note that changing the L3 clock will affect other things as well, like main memory performance. If 400MHz only sort of works maybe a more modest setting like 380 could work?
Linux-SWAT
Forum Addict!
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Is it a bit too much hardcore to be included in Mhz/OPP settings ?
rohezal
Advanced Member
- Joined
- Oct 18, 2009
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- 1,712
Notaz may I ask a few things about it?
First: Is it unstable with the default clock of 600 mhz? It is unstable when you use a lot of neon instructions?
Second: Is the speed of the gpu tied to the speed of RAM? Could it be the RAM is the problem?
notaz
Certified Guru
This stuff doesn't matter, overclocking the GPU has little relation to overclocking the CPU.
Yes and yes, you could probably overclock GPU more if it had separate clock that was not wasn't tied to RAM..
notaz
Certified Guru
I doubt the crash is because the chip reaches some critical temperature, I've used devboards for quite a while and the chip barely gets warm, compared to how hot the charging chip gets while charging a battery, for example.
I finally played a little with
sudo /usr/pandora/scripts/op_sysspeed.sh x
It was not much I tested so far but things looked faster for me.
It was Mupen 64, DraStic and some Flash game.
Most tests were with sysspeed set to 440.
Last test was with 450.
It'd like to get some more testers.
What I could see so far we could get some benefit if we overclock RAM and SGX.
What I want is to get some raw numbers.
So far I only have a subjective impression.
My questions:
1: How far can you get
- Please tell me what Pandora version you use
- Maybe the absolute speed and the % overclocked would be good to get some comparison
2: Which applications use the RAM, SGX and whatever else is overclocked.
3: How stable is it
- Maybe some stress test would be nice
- Or use some applications which use the SGX and need fast RAM and play for half an hour.
If some people are interested let's open a new thread and get some facts.
EDIT:
What's the tool to display the current SGX speed (not the maximal allowed, but the current speed)
Would be useful to check if it really runs at full speed.
sudo /usr/pandora/scripts/op_sysspeed.sh x
It was not much I tested so far but things looked faster for me.
It was Mupen 64, DraStic and some Flash game.
Most tests were with sysspeed set to 440.
Last test was with 450.
It'd like to get some more testers.
What I could see so far we could get some benefit if we overclock RAM and SGX.
What I want is to get some raw numbers.
So far I only have a subjective impression.
My questions:
1: How far can you get
- Please tell me what Pandora version you use
- Maybe the absolute speed and the % overclocked would be good to get some comparison
2: Which applications use the RAM, SGX and whatever else is overclocked.
3: How stable is it
- Maybe some stress test would be nice
- Or use some applications which use the SGX and need fast RAM and play for half an hour.
If some people are interested let's open a new thread and get some facts.
EDIT:
What's the tool to display the current SGX speed (not the maximal allowed, but the current speed)
Would be useful to check if it really runs at full speed.
Last edited by a moderator:
ptitSeb
Serial Porter
I tried, on a Rebirth, the 133MHz GPU/ 400 MHz >MEM Overclock (+ CPU @ 1GHz). I tried PPSSPP & SuperTuxKart and got better fps. I eventually had a crash, after a few hour of use.
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Started new topic: http://boards.openpandora.org/index.php/topic/12478-overclocking-gpuram-lets-get-the-facts/#entry234812
Please help collecting some information .
Please help collecting some information
.
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