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

[H. Nikolaus Schaller]

> Am 11.02.2024 um 08:50 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> But then I did (for both mmc nodes with bus-width 4):
> 
> +++ b/arch/mips/boot/dts/ingenic/lx16.dts
> -       max-frequency = <50000000>;
> +       max-frequency = <5000000>;
> 

I played a little with these values.

Above 15 MHz I could not boot.

At 10 MHz I initially could boot once but got some rcu stall from the kernel.
And then the rootfs was heavily damaged beyond repair.

(Something I often noticed that pressing reset or simply cutting power and
then removing the µSD makes it need minor repair).

After reinstalling the system and kernel with 9 MHz seems to work again
(mmc1 still @ max-frequency = 5 MHz):

root at letux:~# ./diskspeed 
+++ checking /dev/mmcblk0 +++

/dev/mmcblk0:
 Timing O_DIRECT cached reads:    76 MB in  2.02 seconds =  37.56 MB/sec
 Timing O_DIRECT disk reads: 114 MB in  3.01 seconds =  37.85 MB/sec
+++ checking /dev/mmcblk1 +++

/dev/mmcblk1:
 Timing O_DIRECT cached reads:    46 MB in  2.06 seconds =  22.29 MB/sec
 Timing O_DIRECT disk reads:  68 MB in  3.04 seconds =  22.34 MB/sec
root at letux:~# ./diskspeed 
+++ checking /dev/mmcblk0 +++

/dev/mmcblk0:
 Timing O_DIRECT cached reads:    76 MB in  2.03 seconds =  37.51 MB/sec
 Timing O_DIRECT disk reads: 114 MB in  3.01 seconds =  37.83 MB/sec
+++ checking /dev/mmcblk1 +++

/dev/mmcblk1:
 Timing O_DIRECT cached reads:    46 MB in  2.06 seconds =  22.29 MB/sec
 Timing O_DIRECT disk reads:  68 MB in  3.04 seconds =  22.35 MB/sec
root at letux:~# 

So I think we can live with 5 MHz for the moment until we understand
the real cause.

BR,
Nikolaus