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

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Message-ID: <m337kldi92.fsf@t19.piap.pl>
Date:   Tue, 27 Sep 2016 07:27:53 +0200
From:   khalasa@...p.pl (Krzysztof Hałasa)
To:     Andrey Utkin <andrey_utkin@...tmail.com>
Cc:     Hans Verkuil <hverkuil@...all.nl>,
        Andrey Utkin <andrey.utkin@...p.bluecherry.net>,
        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)

Andrey Utkin <andrey_utkin@...tmail.com> writes:

>> Does (only) adding the
>> 
>> 	pci_read_config_word(solo_dev->pdev, PCI_STATUS, &val);
>> 
>> in solo_reg_write() help?
>
> Yes.
> I have posted a patch with this change few days ago, I thought you have
> noticed it.

Well, I think you haven't sent me a copy. Anyway, it would be great to
determine where exactly writes need a flush. Adding it everywhere is a
bit suboptimal, one would think.

Can you share some details about the machine you are experiencing the
problems on? CPU, chipset? I'd try to see if I can recreate the problem.

Alternatively, you could investigate yourself - at first you could put
pci_read_config_word() at the end of subroutines (including return
statements) using solo_reg_write(). And in that solo_p2m_dma_desc(),
before wait_for_completion_timeout(). Then eliminate them using some
sort of binary search to see which ones are required.
-- 
Krzysztof Halasa

Industrial Research Institute for Automation and Measurements PIAP
Al. Jerozolimskie 202, 02-486 Warsaw, Poland