linux-kernel - Re: [RFC PATCH 0/3] staging: remove fbdev drivers

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Message-ID: <1481283856.27965.11.camel@kernel.crashing.org>
Date:   Fri, 09 Dec 2016 22:44:16 +1100
From:   Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:     Daniel Vetter <daniel@...ll.ch>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Noralf Trønnes <noralf@...nnes.org>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>,
        Teddy Wang <teddy.wang@...iconmotion.com>,
        Arnaud Patard <arnaud.patard@...-net.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 0/3] staging: remove fbdev drivers

On Fri, 2016-12-09 at 09:34 +0100, Daniel Vetter wrote:
> Yeah if you have discrete vram then your dumb display driver isn't all
> that pretty. We essentially just have the few drivers Dave hacked up to be
> able to boot some servers. And there's definitely lots of room for more
> shared code for those, and also some better infrastructure and helpers to
> share more cod and make them better.
> 
> The massive pile of dumb framebuffers we all merged over the past 2 years
> all use system/dma memory for scanout, and for those we have the very nice
> cma helpers that take care of everything for you. 

Do they work if the system/DMA memory has to be physically contiguous
and at a fixed address ? The AST "ARM side" GPU is like that.

> So it is possible, only reason vram dumb buffers look worse is that there's
> only 3 and no one cares about them, vs about 20 and a very active community
> of contributors (also for core drm improvements) for the other case.

Well, we could move offb to drm while at it I suppose that would be another
one (offb is the "dumb driver based on pre-programmed output by firmware).

> Althought the MXSFB driver that just landed does use ttm and vram, so
> maybe that's now improving too.

Cheers,
Ben.