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

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Date:   Thu, 12 Jul 2018 15:46:33 +0200
From:   Stefan Agner <stefan@...er.ch>
To:     Leonard Crestez <leonard.crestez@....com>
Cc:     marex@...x.de, dl-linux-imx <linux-imx@....com>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        festevam@...il.com, linux-fbdev@...r.kernel.org,
        Fabio Estevam <fabio.estevam@....com>, marcofrk@...il.com,
        dri-devel@...ts.freedesktop.org, shawnguo@...nel.org,
        linux-arm-kernel@...ts.infradead.org, l.stach@...gutronix.de,
        kernel@...gutronix.de, marek.vasut@...il.com
Subject: Re: [PATCH 1/3] drm: mxsfb: Change driver.name to mxsfb-drm

On 12.07.2018 15:03, Leonard Crestez wrote:
> On Thu, 2018-07-12 at 11:21 +0200, Stefan Agner wrote:
>> On 10.07.2018 11:11, Marek Vasut wrote:
>> > On 07/10/2018 11:06 AM, Stefan Agner wrote:
>> > > This is one of the situation where states quo is kinda the worst
>> > > situation.
>> > >
>> > > Currently imx_v6_v7_defconfig and mxs_defconfig actually still uses
>> > > CONFIG_FB_MXS.
>> > >
>> > > I understand that you'd rather prefer to move forward. I suggest we do
>> > > it in steps.
>> > >
>> > > In 4.19:
>> > >
>> > > - Change DRM driver.name to mxsfb-drm so we avoid conflicts for now
>> >
>> > But this will break mesa if it depends on mxsfb name for ie. etnaviv
>> > binding.
>>
>> Does it? grep -r -e mxsfb in libdrm and mesa master returns nothing.
>>
>> There is also .name in struct drm_driver, which is already set to
>> mxsfb-drm... Is that the one exposed to user space?
> 
> Running etnaviv+x11 with a renamed mxsfb driver works fine on imx6sx-
> sdb.
> 
> Tools like modetest already need -M mxsfb-drm, the drm_driver.name
> seems to be what matters.

Ok, almost thought so, thanks for the confirmation! So we should be
good.

> 
>> - Remove CONFIG_FB_MXS from imx_v6_v7_defconfig/mxs_defconfig now, and
>> only enable CONFIG_DRM_MXSFB=y
> 
> If one of the drivers is renamed then they can coexist: since the
> bindings are distinct one driver will return a probe error and the
> other will bind successfully. This can even be adjusted so that it
> doesn't even print ugly scary errors.
> 
> This can last until somebody implements support for old bindings in the
> drm driver and then FB_MXS can just be deleted.

Yeah I guess that is what Marek don't want because it promotes using
FB_MXS for longer than needed.

I don't care as much since we anyway use the MXSFB DRM driver. However,
what I really dislike is that a kernel compiled with both drivers
currently leads to MXSFB DRM being unusable (because fbdev gets probed
first). I feel removing the MXS_FB is rather harsh, so I *really* would
love to see the MXSFB DRM driver renamed.

--
Stefan