Hi Heiko,

On Wed, Mar 4, 2020 at 12:00 PM Heiko Stübner [off-list ref] wrote:

Am Montag, 2. März 2020, 16:57:02 CET schrieb Mylène Josserand:

quoted

Determine which revision of rk3288 by checking the HDMI version.
According to the Rockchip BSP kernel, on rk3288w, the HDMI
revision equals 0x1A which is not the case for the rk3288 [1].

As these SOC have some differences, the new function
'soc_is_rk3288w' will help us to know on which revision
we are.

what happened to just having a different compatible in the dts?
Aka doing a

rk3288w.dtsi with

#include "rk3288.dtsi"

&cru {
        compatible = "rockchip,rk3288w-cru";
}

I somehow don't expect boards to just switch between soc variants
on the fly.

Also, doing things in mach-rockchip is not very future-proof:

(1) having random soc-specific APIs spanning the kernel feels wrong,
    especially as at some point it might not be contained to our own special
    drivers like the cru. I cannot really see people being enthusiastic if
    something like this would be needed in say the core Analogix-DP bridge ;-)

Indeed.  You're better of registering an soc_device_attribute using
soc_device_register(), after which any driver can use soc_device_match()
to differentiate based on the SoC revision.

(2) I guess the rk3288w will not be the last soc doing this and on arm64 you
    can't do it that way, as there is no mach-rockchip there

There's drivers/soc/rockchip ;-)

So my personal preference would really would be just a specific compatible
for affected ip blocks.

Doing that only for affected IP blocks may miss integration differences.
Of course, you can always resort to soc_device_match() to handle those...

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

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