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

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Message-ID: <20161208152134.wnv4j4i6m5xpoycp@phenom.ffwll.local>
Date:   Thu, 8 Dec 2016 16:21:34 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        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

[back from my walk, the sunset here is stellar ;-)]

On Thu, Dec 08, 2016 at 03:44:30PM +0100, Geert Uytterhoeven wrote:
> Hi Thomas,
> 
> On Thu, Dec 8, 2016 at 3:37 PM, Thomas Petazzoni
> <thomas.petazzoni@...e-electrons.com> wrote:
> > On Thu, 8 Dec 2016 15:22:09 +0100, Geert Uytterhoeven wrote:
> >> > Wut. We have like 20+ small atomic drivers nowdays.
> >>
> >> That's fast! Only two weeks ago you said:
> >>
> >> | Bummer, they still haven't landed. But afaik there's at least 4 of
> >> | them floating around in various places ...
> >
> > You're not talking about the same thing I believe.
> >
> > When Daniel says "small atomic drivers", he talks about the relatively
> > small DRM drivers for SoC display controllers, such as the ones you can
> > find in ARM SoCs.
> >
> > When you say "small driver", you're thinking about drivers for I2C or
> > SPI connected displays.
> 
> No, I wasn't thinking about I2C or SPI connected displays, but about simple
> dumb memory-mapped frame buffers, which is what fbdev was initially
> developed for.

Yeah, small drivers like these we have piles now, things exploded a lot
after atomic landed two years ago. And they seem to shrink with every
release a bit more (since lots more drivers gives you lots more insight
into what other refactorings would make sense). Those we have a big pile
of, and nowadays (at least with developers expirienced with upstream, but
not necessarily with drm) it takes but a few weeks from initial submission
to getting them merged.

What we don't yet have a nice tidy example driver of is the even simpler
"dumb framebuffer behind a slow bus with explicit/manual upload", for like
small i2c/spi panels (and conceptually also usb, even though there bw and
panel size are a bit scaled up). We've gained some really nice helpers for
this this year, and there's 3 drivers in-flight to make use of it. But
since that's right now just a hobbyist effort it's moving a bit slower
(and I was mistaken a few weeks back where I assumed that one of them
landed already).

Cheers, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch