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From: Daniel Vetter <daniel@ffwll.ch>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>,
	Daniel Vetter <daniel@ffwll.ch>, David Airlie <airlied@linux.ie>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Gerd Hoffmann <kraxel@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>, Sam Ravnborg <sam@ravnborg.org>,
	Rob Herring <robh@kernel.org>,
	Emil Velikov <emil.l.velikov@gmail.com>,
	Hans de Goede <hdegoede@redhat.com>,
	bluescreen_avenger@verizon.net,
	Greg KH <gregkh@linuxfoundation.org>,
	DRI Development <dri-devel@lists.freedesktop.org>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v4 0/9] drm: Support simple-framebuffer devices and firmware fbs
Date: Tue, 20 Apr 2021 10:46:47 +0200
Message-ID: <YH6U92Q71ntU6Z1R@phenom.ffwll.local> (raw)
In-Reply-To: <CAMuHMdWcC8O+UzQDQj7Bm4uK_myjFT5D2ccTmneTJYi4SMfCRQ@mail.gmail.com>

On Mon, Apr 19, 2021 at 10:00:56AM +0200, Geert Uytterhoeven wrote:
> Hi Thomas,
> 
> On Fri, Apr 16, 2021 at 11:00 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> > This patchset adds support for simple-framebuffer platform devices and
> > a handover mechanism for native drivers to take-over control of the
> > hardware.
> >
> > The new driver, called simpledrm, binds to a simple-frambuffer platform
> > device. The kernel's boot code creates such devices for firmware-provided
> > framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or boot
> > loader sets up the framebuffers. Description via device tree is also an
> > option.
> 
> I guess this can be used as a replacement for offb, too...
> 
> > Patches 4 to 8 add the simpledrm driver. It's build on simple DRM helpers
> > and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During
> 
> .... if support for 8-bit frame buffers would be added?

Is that 8-bit greyscale or 8-bit indexed with 256 entry palette? Former
shouldn't be a big thing, but the latter is only really supported by the
overall drm ecosystem in theory. Most userspace assumes that xrgb8888
works, and we keep that illusion up by emulating it in kernel for hw which
just doesn't support it. But reformatting xrgb8888 to c8 is tricky at
best. The uapis are all there for setting the palette, and C8 is a defined
format even with atomic kms interface, but really there's not much
userspace for it. In other words, it would work as well as current offb
would, but that's at least that.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

  reply index

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-16  9:00 Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip() Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 2/9] drm/format-helper: Add blitter functions Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 3/9] drm/aperture: Add infrastructure for aperture ownership Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 4/9] drm: Add simpledrm driver Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 5/9] drm/simpledrm: Add fbdev emulation Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 6/9] drm/simpledrm: Initialize framebuffer data from device-tree node Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 7/9] drm/simpledrm: Acquire clocks from DT device node Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 8/9] drm/simpledrm: Acquire regulators " Thomas Zimmermann
2021-04-16  9:00 ` [PATCH v4 9/9] drm/simpledrm: Acquire memory aperture for framebuffer Thomas Zimmermann
2021-04-19  8:00 ` [PATCH v4 0/9] drm: Support simple-framebuffer devices and firmware fbs Geert Uytterhoeven
2021-04-20  8:46   ` Daniel Vetter [this message]
2021-04-20  9:16     ` Geert Uytterhoeven
2021-04-20 11:11       ` Daniel Vetter
2021-04-20  9:22     ` Gerd Hoffmann
2021-04-20  9:27       ` Geert Uytterhoeven
2021-04-26 12:22         ` Thomas Zimmermann
2021-04-26 19:05           ` Geert Uytterhoeven
2021-04-26 12:18     ` Thomas Zimmermann
2021-04-26 15:08       ` Daniel Vetter
2021-04-29 10:24 ` Maxime Ripard

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