Re: [PATCH] media: fdp1: Reduce FCP not found message level to debug

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Hi Geert,

On 09/07/2019 11:13, Geert Uytterhoeven wrote:
> Hi Kieran,
> 
> On Tue, Jul 9, 2019 at 12:07 PM Kieran Bingham
> <kieran.bingham+renesas@xxxxxxxxxxxxxxxx> 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.
> 
> Gr{oetje,eeting}s,

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.

So, with that and a precedent for this change in VSP1, I'm happy here.

Reviewed-by: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>




> 
>                         Geert
> 




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