linux-kernel - Re: solo6010 modprobe lockup since e1ceb25a (v4.3 regression)

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Message-ID: <af508dbf-e516-fcf1-3992-5f214bdd03b1@xs4all.nl>
Date:   Thu, 15 Sep 2016 15:25:03 +0200
From:   Hans Verkuil <hverkuil@...all.nl>
To:     Andrey Utkin <andrey_utkin@...tmail.com>
Cc:     Andrey Utkin <andrey.utkin@...p.bluecherry.net>,
        Krzysztof Hałasa <khalasa@...p.pl>,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Ismael Luceno <ismael@...ev.co.uk>,
        Bluecherry Maintainers <maintainers@...echerrydvr.com>
Subject: Re: solo6010 modprobe lockup since e1ceb25a (v4.3 regression)

On 09/15/2016 03:19 PM, Andrey Utkin wrote:
> On Thu, Sep 15, 2016 at 03:15:53PM +0200, Hans Verkuil wrote:
>> It could be related to the fact that a PCI write may be delayed unless
>> it is followed by a read (see also the comments in drivers/media/pci/ivtv/ivtv-driver.h).
> 
> Thanks for explanation!
> 
>> That was probably the reason for the pci_read_config_word in the reg_write
>> code. Try putting that back (and just that).
> 
> In this case reg_write becomes not atomic, thus spinlock would be
> required again here, right?

That depends on whether you can have calls to this function in parallel.

But I get the feeling that it might be easier to just revert the patch.

Regards,

	Hans