> “bone kernel”
>
> That’s important. The TI kernels are not usable for my application. I need
> to use the bone kernel. (At least for the 4.9 and 4.14 series… haven’t had
> time to test with the TI 4.19 series kernels)
>
>
> Ah. I see. What sorts of differences are there between the TI kernels and
> the Bone kernels? Is there some reason the Bone don't have the MCP23S08
> module enabled? Wondering if a bug/feature request might make sense…
Just added..
> Honestly, I have no idea what the “official” differences are and why some
> modules are available in one and not the other. Likely just someone
> requested something. At some point, a “diff” of the configs and unifying
> the optional modules of it may make sense, not really sure.
They've just evolved differently, from the same 3.8.x-bone base..
keeping them in-sync has been...<fun>.... The bone series goes thru
every kernel release, and i like to merge the good stuff back into the
-ti kernel, which it self has to deal with ti modules that don't like
optimizations (thumb2)
3.8.x-bone -> 3.9.x-bone -> ...... -> 4.9.x-bone -> ..... ->
4.14.x-bone -> ... 4.19.x-bone -> 4.20.x-bone...
-> 3.14.x-ti -> 4.1.x-ti -> 4.4.x-ti -> 4.9.x-ti -> 4.14.x-ti -> 4.19.x-ti
>
> In my particular case, I *believe* the power management stuff that is in the
> TI kernel is screwing up the timing to access anything in the L4_WKUP
> interconnect (which includes GPIO0). For folks that value the power
> management stuff, the TI kernel is much better. It contains the cpu IDLE
> driver and a bunch of other things that allow it to lower the power usage.
> In my case, I don’t care about any of that. Even with the bone kernel, I
> lock the CPU at 1ghz. I need more predictable and consistent access to the
> gpio pins (all of them). With the TI kernel, access to GPIO1-3 (via the
> PRU) is very consistent, but access to GPIO0 can have several hundred ns
> delays which I cannot have (relatively infrequent, once or twice a second,
> but still too often). I KNOW the CPU idle stuff in the TI kernel plays a
> large part of the problem. If I use cpupower to turn off the idle states,
> 90% of the delays go away (so once every 10 seconds or so). Anyway, the
> bone kernel doesn’t have a bunch of the PM things so I don’t see any of the
> issues with it. Of course, it might not be PM at all. Could be something
> else completely different between the kernels.
Regards,
--
Robert Nelson
https://rcn-ee.com/
--
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