linux-kernel - Re: [PATCH] drm/imagination: DRM_POWERVR should depend on ARCH

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Date:   Wed, 29 Nov 2023 09:45:45 +0100
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Maxime Ripard <mripard@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Frank Binns <frank.binns@...tec.com>,
        Donald Robson <donald.robson@...tec.com>,
        Matt Coster <matt.coster@...tec.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Sarah Walker <sarah.walker@...tec.com>,
        Nishanth Menon <nm@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Tero Kristo <kristo@...nel.org>, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] drm/imagination: DRM_POWERVR should depend on ARCH_K3

Maxime Ripard <mripard@...nel.org> writes:

Hello Maxime,

> Hi,
>
> On Tue, Nov 28, 2023 at 08:16:18PM +0100, Geert Uytterhoeven wrote:
>> On Tue, Nov 28, 2023 at 8:03 PM Javier Martinez Canillas
>> <javierm@...hat.com> wrote:
>> > Geert Uytterhoeven <geert+renesas@...der.be> writes:
>> > > The Imagination Technologies PowerVR Series 6 GPU is currently only
>> > > supported on Texas Instruments K3 AM62x SoCs.  Hence add a dependency on
>> > > ARCH_K3, to prevent asking the user about this driver when configuring a
>> > > kernel without Texas Instruments K3 Multicore SoC support.
>> > >
>> > > Fixes: 4babef0708656c54 ("drm/imagination: Add skeleton PowerVR driver")
>> > > Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
>> > > ---
>> >
>> > Indeed. Although I wonder what is the supposed policy since for example
>> > the DRM_PANFROST symbol only depends on ARM || ARM64 and others such as
>> 
>> I think ARM Mali is sufficiently ubiquitous on ARM/ARM64 systems to
>> have just an ARM/ARM64 dependency...
>> 
>> > DRM_ETNAVIV don't even have an SoC or architecture dependency.
>> 
>> Vivante GPUs are found in DTS files on at least 4 architectures.
>> Might be worthwhile to add some dependencies, though...
>> 
>> > In any case, I agree with you that restricting to only K3 makes sense.
>> 
>> I am looking forward to adding || SOC_AM33XX || ARCH_RENESAS || ...,
>> eventually ;-)
>
> I disagree. This is to handle a generic IP, just like panfrost, lima, or
> etnaviv, and we certaintly don't want to maintain the Kconfig list of
> every possible architecture and SoC family it might or might not be
> found.
>

Thanks for the clarification. Then the policy is to have a depends on
ARCH_$FOO if the IP block is tied to a particular SoC or SoC family ?

For example, DRM_V3D has:

depends on ARCH_BCM || ARCH_BRCMSTB || ARCH_BCM2835 || COMPILE_TEST

If the IP block is generic and could be integrated with any SoC, then it
should not have a dependency as you said.

> GPUs supposed to be handled are spread across 4 architectures (x86,
> riscv, arm, arm64, mips?), and in arm/arm64 alone we have at least 5
> platforms that might use it (allwinner, ti, mediatek, renesas, rockchip)
>
> It didn't make sense for panfrost, or etnaviv. It doesn't make sense for
> that driver either. Especially for something that olddefconfig can
> handle just fine.
>

I think then that we should drop the arch and SoC dependency for these GPU
drivers and just leave the symbols they really depend on (e.g: DRM, MMU) ?

> Maxime

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat