Re: [PATCH 06/10] ARM: mach-airoha: Rework support and directory structure

[Andrew Davis]

On 5/15/23 11:31 AM, Russell King (Oracle) wrote:
> On Mon, May 15, 2023 at 11:02:30AM -0500, Andrew Davis wrote:
> > Having a platform need a mach-* directory should be seen as a negative,
> > it means the platform needs special non-standard handling. ARM64 support
> > does not allow mach-* directories at all. While we may not get to that
> > given all the non-standard architectures we support, we should still try
> > to get as close as we can and reduce the number of mach directories.
> >
> > The mach-airoha/ directory, and files within, provide just one "feature":
> > having the kernel print the machine name if the DTB does not also contain
> > a "model" string (which they always do). To reduce the number of mach-*
> > directories let's do without that feature and remove this directory.
>
> I'm guessing this is copy-n-pasted description. However:
> > -static const char * const airoha_board_dt_compat[] = {
> > -	"airoha,en7523",
> > -	NULL,
> > -};
> > -
> > -DT_MACHINE_START(MEDIATEK_DT, "Airoha Cortex-A53 (Device Tree)")
> > -	.dt_compat	= airoha_board_dt_compat,
> > -MACHINE_END
>
> If this is actually used, then it will have the effect of providing a
> "machine" that has both l2c_aux_mask and l2c_aux_val as zero, whereas
> the default one has l2c_aux_mask set to ~0.

Given we set l2c_aux_mask to ~0 as a default for "Generic" DT system I
had assumed this was safe, but no I cannot prove it for this board as
I don't have one.

I wonder if we should have some way to set this in DT, that would
let us drop some more MACHINE defines that exist only to set
the l2c_aux_val/mask..

> This has the effect of _not_ calling l2x0_of_init() - but you don't
> mention this. You probably should, and you should probably state why
> that is safe (assuming you've even realised you've made this change!)

Reverse question, did the folks adding this support know this had
the effect of changing l2c_aux_mask from the default?

For now I'll resend this series with only the first 5 patches which
should be trivially safe. The later ones I can send after double
checking on l2x0_of_init().

Andrew