[Letux-kernel] X1600 / LX16 support - here: adding MMC - MAJOR BREAKTHROUGH

[Paul Boddie]

On Sunday, 11 February 2024 17:00:58 CET H. Nikolaus Schaller wrote:
> 
> The result of this effort is tested on X1600 (positively) and CI20 (no
> negative effects observed and BTW, the mmc speed is just 11 MB/sec!) and
> the sources are here:
> 
> 	https://git.goldelico.com/?p=letux-kernel.git;a=shortlog;h=refs/
heads/work-x1600-v4
> 
> So we now have a very good basis for incremental improvements. Please share
> here on the mailing list if you have something.

It has been hard to track all of the differences introduced here, so I 
obtained this branch and attempted to boot. As noted previously, although the 
SD card could be accessed, it wasn't possible to use the max-frequency of 
50MHz, or at least I saw some fairly worrying stack traces appear in the 
console.

So, I have applied some changes to the PLL configuration to a new branch based 
on this one:

paulb-work-x1600-v4

Running with a 50MHz max-frequency seems to be successful. I looked at the 
clk_summary debugfs file and saw that many of the reported frequencies were 
previously ten times too small. I think my changes fix that, but it seems very 
odd, and I wonder what effect changing the max-frequency may have had, even 
though that is only supposed to apply to MSC0.

Anyway, feel free to take a look.

Paul