[PATCH 5/5] arm: kirkwood: Do not overwrite CONFIG_SYS_TCLK

[Pali Rohár]

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/arm/mach-kirkwood/common.c?h=v3.15#n542
> 
> #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@kernel.org/