linux-kernel - Re: [PATCH 1/3] drm: mxsfb: Change driver.name to mxsfb-drm

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Message-ID: <b3fa74c5110b45e5992920485749869ab1f7ebce.camel@nxp.com>
Date:   Fri, 15 Jun 2018 22:42:43 +0000
From:   Leonard Crestez <leonard.crestez@....com>
To:     "festevam@...il.com" <festevam@...il.com>,
        "stefan@...er.ch" <stefan@...er.ch>,
        "marex@...x.de" <marex@...x.de>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>
CC:     dl-linux-imx <linux-imx@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
        Fabio Estevam <fabio.estevam@....com>,
        "marcofrk@...il.com" <marcofrk@...il.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>
Subject: Re: [PATCH 1/3] drm: mxsfb: Change driver.name to mxsfb-drm

On Fri, 2018-06-15 at 23:36 +0200, Marek Vasut wrote:
> On 06/15/2018 10:58 PM, Leonard Crestez wrote:
> > On Fri, 2018-06-15 at 16:47 -0300, Fabio Estevam wrote:
> > > On Fri, Jun 15, 2018 at 4:43 PM, Leonard Crestez
> > > <leonard.crestez@....com> wrote:

> > > > The FBDEV driver uses the same name and both can't be registered at the
> > > > same time. Fix this by renaming the drm driver to mxsfb-drm
> > > 
> > > Stefan sent the same patch a few days ago:
> > 
> > In that thread there is a proposal for removing the old fbdev/mxsfb
> > driver entirely.
> > 
> > That would break old DTBs, isn't this generally considered bad? Also,
> > are we sure the removal of fbdev/mxsfb wouldn't lose any features?
> > 
> > What my series does is make both drivers work with the same kernel
> > image and turns the choice into a board-level dtb decision. Supporting
> > everything at once seems desirable to me and it allows for a very
> > smooth upgrade path.
> 
> Having two drivers in the kernel with different set of bugs is always bad.
> 
> > The old driver could be removed later, after all users are converted.
> 
> Both drivers were in for long enough already. And let's be realistic,
> how many MX23/MX28 users of old DTs with new kernels are there who
> cannot update the DT as well ?

Grepping for "display =" in arch/arm/boot/dts/imx* I see that old
bindings are also used by 3rd-party boards for imx6/7:
 * imx6sx-nitrogen6sx
 * imx6ul-geam
 * imx6ul-isiot
 * imx6ul-opos6uldev
 * imx6ul-pico-hobbit
 * imx6ul-tx6ul
 * imx7d-nitrogen7

Converting everything might be quite a bit of work, and explicitly
supporting old bindings is also work.

It is very confusing that there is a whole set of displays for imx6/7
which are supported by upstream but only with a non-default config.
While it is extremely common in the embedded field to have custom
configs the default one in the kernel should try to "just work".

Couldn't this patch series be considered a bugfix? It was also
surprisingly small.

--
Regards,
Leonard