[Letux-kernel] [Lenny400] JZ4730/Minibook framebuffer driver updates

Daniel Glöckner daniel-gl at gmx.net
Sun Sep 10 23:50:32 CEST 2017


On Sun, Sep 10, 2017 at 08:55:15PM +0200, H. Nikolaus Schaller wrote:
> > 5. The U-Boot that we don't dare to replace might be too old to load the
> >   kernel from an SDHC card.
> Ah, yes. That could happen.
> But is quite unlikely. There is a first FAT partition which contains the uImage
> and that is everything which should be loaded. I'd expect that as long as the
> first partition is small enough, U-Boot will even find it on the first sectors
> of an SDXC card.

mmc_init_card_state in jz_mmc.c sets bit 30 in the OCR register and
divides the offset by 512 if the CSD version is not 1.0, so it should
already handle SDHC correctly.

> I still have to remove dust from my devices (one is still missing) and find
> out which ones are still booting from flash with the built-in 2.4 kernel.

I also haven't started my Letux 400 in a long time.
Maybe I should recharge the battery...

> Worst expectation is that we do not see anything after 
> Starting kernel...

Do we already have code for early_printk?

> This is more difficult, but not impossible to debug (even without JTAG). I
> had that on the GTA04 several times during our long journey towards latest
> Letux kernels.

I just designed and ordered PCBs for a JTAG/UART breakout board after I
failed to solder more than two enamel wires in one hour to the 0.5mm FFC
connectors that I bought some time ago. But it will take 3-4 weeks for
the PCBs to arrive. Maybe I'll just solder wires to the test points on
the Letux 400 PCB till then.

Has anyone ever tried to debug a Jz4730 with OpenOCD?

Best regards,


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