From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>,
Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Linux Media Mailing List <linux-media@vger.kernel.org>,
Linux-Renesas <linux-renesas-soc@vger.kernel.org>
Subject: Re: [PATCH] media: fdp1: Reduce FCP not found message level to debug
Date: Tue, 9 Jul 2019 12:28:21 +0200 [thread overview]
Message-ID: <CAMuHMdWQDriyMkkOHNO=neNsH4Q1c2ALRg4aj1+vyez16a0Ubw@mail.gmail.com> (raw)
In-Reply-To: <bee131c3-e07e-6d6f-9315-774f638da53f@ideasonboard.com>
Hi Kieran,
On Tue, Jul 9, 2019 at 12:18 PM Kieran Bingham
<kieran.bingham+renesas@ideasonboard.com> wrote:
> On 09/07/2019 11:13, Geert Uytterhoeven wrote:
> > On Tue, Jul 9, 2019 at 12:07 PM Kieran Bingham
> > <kieran.bingham+renesas@ideasonboard.com> wrote:
> >> On 09/07/2019 10:59, Geert Uytterhoeven wrote:
> >>> When support for the IPMMU is not enabled, the FDP driver may be
> >>> probe-deferred multiple times, causing several messages to be printed
> >>> like:
> >>>
> >>> rcar_fdp1 fe940000.fdp1: FCP not found (-517)
> >>> rcar_fdp1 fe944000.fdp1: FCP not found (-517)
> >>>
> >>> Fix this by reducing the message level to debug level, as is done in the
> >>> VSP1 driver.
> >>
> >> Does the lack of IPMMU prevent the FDP1 being loaded entirely?
> >
> > No it doesn't.
> > If CONFIG_IPMMU_VMSA=n,
> >
> > rcar_fdp1 fe940000.fdp1: FCP not found (-517)
> > rcar_fdp1 fe944000.fdp1: FCP not found (-517)
> > rcar_fdp1 fe940000.fdp1: FCP not found (-517)
> > rcar_fdp1 fe944000.fdp1: FCP not found (-517)
> > rcar_fdp1 fe940000.fdp1: FCP not found (-517)
> > rcar_fdp1 fe944000.fdp1: FCP not found (-517)
> > rcar_fdp1 fe940000.fdp1: Device registered as /dev/video8
> > rcar_fdp1 fe944000.fdp1: Device registered as /dev/video9
> >
> > So the driver succeeds, eventually.
> >
> > If CONFIG_IPMMU_VMSA=y, it succeeds sooner:
> >
> > rcar_fdp1 fe940000.fdp1: Device registered as /dev/video0
> > rcar_fdp1 fe944000.fdp1: Device registered as /dev/video1
> >
> > Always be prepared to handle -EPROBE_DEFER.
>
> On the basis that the driver is not prevented from loading, then the
> message does indeed become more of a debug print.
>
> I wonder if it's better to print something different in the event of
> EPROBE_DEFER vs another actual error preventing the loading of the
> driver, but in either case if someone hits an issue they're likely to
> start adding/enabling debug.
That's why some driver suppress printing errors for -EPROBE_DEFER.
> So, with that and a precedent for this change in VSP1, I'm happy here.
>
> Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Thanks!
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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
prev parent reply other threads:[~2019-07-09 10:28 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-09 9:59 [PATCH] media: fdp1: Reduce FCP not found message level to debug Geert Uytterhoeven
2019-07-09 10:07 ` Kieran Bingham
2019-07-09 10:13 ` Geert Uytterhoeven
2019-07-09 10:18 ` Kieran Bingham
2019-07-09 10:28 ` Geert Uytterhoeven [this message]
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