Re: [PATCH v1 2/2] drivers/gpu/drm: don't select DMA_CMA or CMA from aspeed or etnaviv

From: Linus Walleij <linus.walleij@linaro.org>
To: David Hildenbrand <david@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>, Joel Stanley <joel@jms.id.au>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Andrew Jeffery <andrew@aj.id.au>,
	Lucas Stach <l.stach@pengutronix.de>,
	Russell King <linux+etnaviv@armlinux.org.uk>,
	Christian Gmeiner <christian.gmeiner@gmail.com>,
	Mike Rapoport <rppt@kernel.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Michal Simek <michal.simek@xilinx.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	Peter Collingbourne <pcc@google.com>,
	linux-aspeed <linux-aspeed@lists.ozlabs.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	The etnaviv authors <etnaviv@lists.freedesktop.org>,
	Linux Fbdev development list <linux-fbdev@vger.kernel.org>
Subject: Re: [PATCH v1 2/2] drivers/gpu/drm: don't select DMA_CMA or CMA from aspeed or etnaviv
Date: Thu, 8 Apr 2021 14:49:51 +0200	[thread overview]
Message-ID: <CACRpkdYizKGhtYzE+22oZAduLNCOGP9Vbp=LQbXG1C-a+MyMcg@mail.gmail.com> (raw)
In-Reply-To: <3a2d64a7-8425-8daf-17ee-95b9f0c635f9@redhat.com>

On Thu, Apr 8, 2021 at 2:01 PM David Hildenbrand <david@redhat.com> wrote:

> > This is something you could do using a hidden helper symbol like
> >
> > config DRMA_ASPEED_GFX
> >         bool "Aspeed display driver"
> >         select DRM_WANT_CMA
> >
> > config DRM_WANT_CMA
> >         bool
> >         help
> >            Select this from any driver that benefits from CMA being enabled
> >
> > config DMA_CMA
> >         bool "Use CMA helpers for DRM"
> >         default DRM_WANT_CMA
> >
> >           Arnd
> >
>
> That's precisely what I had first, with an additional "WANT_CMA" --  but
> looking at the number of such existing options (I was able to spot 1 !)

If you do this it probably makes sense to fix a few other drivers
Kconfig in the process. It's not just a problem with your driver.
"my" drivers:

drivers/gpu/drm/mcde/Kconfig
drivers/gpu/drm/pl111/Kconfig
drivers/gpu/drm/tve200/Kconfig

certainly needs this as well, and pretty much anything that is
selecting DRM_KMS_CMA_HELPER or
DRM_GEM_CMA_HELPER "wants" DMA_CMA.

Yours,
Linus Walleij