[Letux-kernel] JZ4730 kernel support

Paul Boddie paul at boddie.org.uk
Tue Oct 15 18:13:19 CEST 2019


On Tuesday 15. October 2019 09.57.05 H. Nikolaus Schaller wrote:
> 
> Thanks! I have applied it and it compiles with the letux_defconfig. So I
> will include it in the next -rc build.
> 
> One tiny note: would be good if there is a signed-off, which is a
> requirement for upstreaming.

I'll specify the --signoff option to git format-patch this time.

> I have also scanned the source tree for '#if 0' and there is one in
> arch/mips/jz4740/time.c

So, I had to take a look at the JZ4740 documentation and my modifications to 
the Fiasco microkernel to remind myself of how the JZ4730 does things. There 
are a few differences that require the code to be changed rather than 
parameterised, and I suspected that there would be other places where similar 
corresponding changes need to be made.

Sure enough, I found the drivers/clk/ingenic/tcu.c file containing the timer 
control functions. Due to the differences in the JZ4730, I ended up having to 
add separate register definitions in a new file:

include/linux/mfd/ingenic-tcu-jz4730.h

The old jz4730_timer.h header file might conceivably be eliminated at some 
point given that the above clock driver code and definitions do largely the 
same thing. This would affect the arch/mips/jz4740/timer.c file, of course.

There should still be places where the timer interrupts are handled, but I 
didn't find these just now when quickly searching for possible locations.

[...]

> Well, I should definitively find time to set up a testing environment...
> Now as I have achieved a breakthrough with OMAP-PVR/SGX, I hope I can
> reprioritize some things.

I read the remarks about PowerVR and saw the article you referenced where 
someone had managed to configure their OMAP-based system to use the drivers 
again, so I guess there is hope for this. Not that this affects the Minibook 
directly, though. ;-)

Paul

P.S. The cumulative patch (including the previous patches) has been attached, 
with signed-off, to this message.
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