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Latest Rockbox not working on Nano

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GodEater:
Llorean's post answers that question - please read it.

mitchelln:

--- Quote from: GodEater on November 06, 2007, 05:48:59 AM ---Llorean's post answers that question - please read it.

--- End quote ---
We both must've been replying at the same time, so I didn't see your link. :) Thanks for heads up.

mitchelln:
Okay. I've had time to read the whole multi-page post now. I have to say that I do find it odd what has gone on here. From what I can see, the clock was upped to 80MHz for no real solid reason other than "technically and theoretically it can be done". People then reported that is caused problems and the change was not reverted. This is the first time I've seen this happen on Rockbox.

As an embedded hardware engineer, I have to say that this has all the classic symptoms of a device that is being clocked beyond it's limit. I cannot see anything to disprove this. Later Nano's probably cope due to a different PCB issue or a later batch of core (later batches always tend to overclock better). When you overclock a chip you will get all sorts of weird behaviour. It will upset bus and memory timings that may make it look like another part is at fault. The very fact that this has gone unfixed for many weeks indicates to me that this is hardware related. Just my professional opinion ;)

Thanks to Neil Schemenauer for providing a 75MHz build. It works great on my Nano.

Llorean:
We know that the PP502x series chips used in iPods either have a speed of 80mhz or 100mhz. We chose 80 as a maximum rather than clock different iPods at different speeds.

Whatever the problem is seems not to be with the clock speed itself, but as I've said, with timing relative to some other piece of hardware in the device.

If it truly, truly is a hardware fault that prevents certain devices from working, then coding a fix for it isn't a workaround any more: It's a fix.

Until such time as it's actually identified what's wrong, 80mhz is known to be a speed that is valid for the processor, and evidence suggests the problem is actually in other hardware in the device not being used quite properly.

One of the biggest benefits of going from 75mhz to 80mhz: Music is less likely to skip when the device is under load. Evidence is very, very strong that this processor speed is supported, and plenty of signs suggest it's other hardware in the device is the problem, but as of yet there's no firm evidence that it's a hardware fault, and it could very easily be a case of us not initializing or communicating with that other hardware right yet.

If we do establish though  that the only way to keep these Nanos from crashing is to clock it down, rest assured, it will be done. Our intent isn't to screw over users, it's to get things fixed properly.

As I've said, users have now reported going back to 75mhz and still experiencing these bugs when their device gets too hot, and some have revealed that their device would occasionally glitch like this in the past with them thinking that it was more just "Rockbox isn't done yet" than anything they should be reporting, so signs suggest rather strongly that just clocking back to 75mhz isn't going to fix it, just put it in hiding again, and if anything should be done it should be someone investigating the actual problem and looking for a _full_ fix rather than one that goes from "Some people experience it" to merely "Only a few people experience it" because then you're just choosing to screw over less people for your own personal benefits rather than actually concentrate on fixing the problem.

So I think you can see why I favour a real fix: I'd rather the problem be gone for good, and properly fixed.

mitchelln:
Great response Llorean. Thanks :)

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