Re: [PATCH] usb: dwc3: make USB_DWC3_EXYNOS independent

[Krzysztof Kozlowski]

On 03/03/2021 17:49, Krzysztof Kozlowski wrote:
> > And "new drivers" are almost always not really "new" as everyone uses
> > much the same IP blocks.  As proof of this patch where the DWC3 IP block
> > is being used by multiple SoC vendors.  To handle that, you split out
> > the SoC-specific portions into sub-drivers, so that you can build a
> > single image of the driver that works on multiple platforms.  Nothing
> > new, we've been doing this for years, it's just that out-of-mainline SoC
> > trees that think they can touch "core IP block code" break this all the
> > time, which is what I am pushing back on.
>
> I am perfectly fine with (and like it!) putting dwc3 exynos back into 
> base/main dwc3  and getting rid of USB_DWC3_EXYNOS entirely. But this 
> was not part of this patch...
>
> > Anyway, this is just me as a driver subsystem maintainer being grumpy to
> > see ARCH_ dependancies on tiny little things like SoC-portions for
> > generic IP drivers.  Or on individual drivers (i.e. Samsung serial port
> > driver), where they don't belong at all.
>
> At least with Samsung serial driver we see adding new SoC - Apple M1.
>
> Here, the guys in Samsung want to tweak several kernel parts to work 
> with their out-of-tree code without contributing this code back. It's 
> not a community-friendly approach. The upstream kernel should be tweaked 
> to the out-of-tree unknown, hidden and uncontrollable code.

Eh, obviously I wanted to say:
The upstream kernel should *not* be tweaked to the out-of-tree unknown, 
hidden and uncontrollable code.

> Instead I expect from Samsung to contribute the basic Exynos9 support to 
> the upstream.

Best regards,
Krzysztof