linux-kernel - Re: [PATCH v3] ata/pata_buddha: Probe via modalias instead of initcall

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Message-ID: <CAMuHMdXwWHz9pkOKf4NiPF=GXS-vTU20Hu9QNni9ZWVds2bWGw@mail.gmail.com>
Date:   Mon, 29 Jul 2019 17:41:11 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Max <max@...as.org>
Cc:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Jens Axboe <axboe@...nel.dk>,
        John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        Michael Schmitz <schmitzmic@...il.com>,
        linux-ide@...r.kernel.org,
        "Linux/m68k" <linux-m68k@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] ata/pata_buddha: Probe via modalias instead of initcall

Hi Max,

On Mon, Jul 29, 2019 at 5:38 PM Max <max@...as.org> wrote:
> On 07/29/2019 05:26 PM, Geert Uytterhoeven wrote:
> >> We *could* also temporarily split off a pata_buddha_xsurf driver: pata_buddha would be auto-probed by the new framework, and pata_buddha_xsurf would do the old module_init() dance.
> >> That is, until the MFD conversion happens.
> >
> > Or add temporarily a late_initcall() to find all X-Surf boards using
> > zorro_find_device(), create fake zorro_device_id entries, and pass both
> > to pata_buddha_probe()?  A big ugly, but that should work.
>
> Sounds good, and it replaces modile_init() at the same time. I'll implement this.

Thanks!

> >>> Your single Buddha should be sufficient to convert pata_buddha.c from
> >>> a plain Zorro driver to an MFD cell driver, and test it.
> >>> I expect the buddha-mfd.c MFD driver from my zorro-mfd branch to
> >>> work as-is, or with very minor changes.
> >>>
> >>> However, to keep X-Surf working, this needs to be synchronized with
> >>> a Zorro MFD conversion of the zorro8390 driver, too.
> >>
> >> Yeah, this second part is where I get caught up. I'd really like to test this with a real X-Surf, or have someone test it, before sending it upstream.
> >
> > Of course it should be tested ;-)
> > Converting zorro8390.c from a zorro driver to an MFD cell driver should
> > not require that many changes, most bugs should be caught by code review.
> > I already have a skeleton 8390-cell.c driver in my zorro-mfd branch.
>
> Honestly, at this point I'd rather do the hack above and keep the MFD stuff for later. Let's take it step by step. I'd prefer not to touch 8390 for now, unless I can get my hands on an X-Surf. I'd like to help with the MFD stuff as a way to enable the clockport and my SilverSurfer on it, but for the moment I'd rather move that further down the road.

OK, fine for me, of course.

> >>> Yes, the clockport could be added as an extra MFD cell.  Later, drivers can
> >>> be written to bind against the clockport cell.
> >>
> >> Yes, but how can we assign specific drivers to specific clockports? As they are non-enumerable (are they?), we can't auto-probe them.
> >
> > That's something the user has to configure.
> > The Buddha MFD driver registers an "a1200-clockport" cell, which is
> > really a separate platform device.
> > The user writes the name of the actual driver to use to the device's
> > driver_override file in sysfs, after which the driver is bound
> > automatically.  See Documentation/ABI/testing/sysfs-bus-platform,
>
> That sounds just like what I was hoping for, thanks.

I'm happy you like it ;-)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds