From: Dmitry Osipenko <digetx@gmail.com>
To: Jon Hunter <jonathanh@nvidia.com>,
Laxman Dewangan <ldewangan@nvidia.com>,
Vinod Koul <vkoul@kernel.org>,
Thierry Reding <thierry.reding@gmail.com>,
Ben Dooks <ben.dooks@codethink.co.uk>
Cc: dmaengine@vger.kernel.org, linux-tegra@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1] dmaengine: tegra-apb: Handle DMA_PREP_INTERRUPT flag properly
Date: Wed, 8 May 2019 15:37:14 +0300 [thread overview]
Message-ID: <cbe8352c-c1c7-12a7-c658-82e7ffee0be8@gmail.com> (raw)
In-Reply-To: <287d7e67-1572-b4f2-d4bb-b1f02f534d47@nvidia.com>
08.05.2019 12:24, Jon Hunter пишет:
>
> On 05/05/2019 19:12, Dmitry Osipenko wrote:
>> The DMA_PREP_INTERRUPT flag means that descriptor's callback should be
>> invoked upon transfer completion and that's it. For some reason driver
>> completely disables the hardware interrupt handling, leaving channel in
>> unusable state if transfer is issued with the flag being unset. Note
>> that there are no occurrences in the relevant drivers that do not set
>> the flag, hence this patch doesn't fix any actual bug and merely fixes
>> potential problem.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>
> From having a look at this, I am guessing that we have never really
> tested the case where DMA_PREP_INTERRUPT flag is not set because as you
> mentioned it does not look like this will work at all!
>
> Is there are use-case you are looking at where you don't set the
> DMA_PREP_INTERRUPT flag?
No. I just noticed it while was checking whether we really need to
handle the BUSY bit state for the Ben's "accurate reporting" patch.
> If not I am wondering if we should even bother supporting this and warn
> if it is not set. AFAICT it does not appear to be mandatory, but maybe
> Vinod can comment more on this.
The warning message will be also okay if it's not mandatory.
next prev parent reply other threads:[~2019-05-08 12:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-05 18:12 [PATCH v1] dmaengine: tegra-apb: Handle DMA_PREP_INTERRUPT flag properly Dmitry Osipenko
2019-05-08 9:24 ` Jon Hunter
2019-05-08 12:37 ` Dmitry Osipenko [this message]
2019-05-21 4:55 ` Vinod Koul
2019-05-21 13:46 ` Dmitry Osipenko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=cbe8352c-c1c7-12a7-c658-82e7ffee0be8@gmail.com \
--to=digetx@gmail.com \
--cc=ben.dooks@codethink.co.uk \
--cc=dmaengine@vger.kernel.org \
--cc=jonathanh@nvidia.com \
--cc=ldewangan@nvidia.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tegra@vger.kernel.org \
--cc=thierry.reding@gmail.com \
--cc=vkoul@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox