On Tuesday 16 August 2022 21:38:51 Pali Rohár wrote:
Meanwhile I have found following email thread: https://lore.kernel.org/linux-arm-kernel/20121020113800.GC21046@lunn.ch/t/#u
Where are more 6281 boards with 166 MHz TCLK and there is interesting output: $ dmesg | grep -i tclk [ 5.851008] Kirkwood: MV88F6281-A0, TCLK=200000000
Which means that old kernel version had TCLK detection code. I grepped git linux history and I successfully found it: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/arch/a...
#define SAMPLE_AT_RESET (DEV_BUS_VIRT_BASE + 0x0030)
static int __init kirkwood_find_tclk(void) { u32 dev, rev;
kirkwood_pcie_id(&dev, &rev);
if (dev == MV88F6281_DEV_ID || dev == MV88F6282_DEV_ID) if (((readl(SAMPLE_AT_RESET) >> 21) & 1) == 0) return 200000000;
return 166666667; }
So for TCLK detection is used BIT 21 of already mentioned 0x10030 Sample at Reset Register.
I'm going to prepare a patch which will fix this issue for 88F6281 SoCs.
Done! Please test it! https://patchwork.ozlabs.org/project/uboot/patch/20220816200016.18288-1-pali...