From: Flavio Suligoi <f.suligoi@asem.it>
To: Mark Brown <broonie@kernel.org>
Cc: Daniel Mack <daniel@zonque.org>,
Haojian Zhuang <haojian.zhuang@gmail.com>,
Robert Jarzmik <robert.jarzmik@free.fr>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 2/2] spi: pxa2xx: use a module softdep for dw_dmac
Date: Thu, 11 Apr 2019 07:14:06 +0000 [thread overview]
Message-ID: <7ad025c8049e4e828ce75ef1e41dcbfd@asem.it> (raw)
In-Reply-To: <20190410152820.GT6106@sirena.org.uk>
> > I think that the problem could be related to how the DMA channel is
> requested.
> > At the moment the function used are:
>
> > pxa2xx_spi_dma_setup --> dma_request_slave_channel_compat -->
> > --> __dma_request_slave_channel_compat --> dma_request_slave_channel -->
> > --> dma_request_chan
>
> > Actually the final function "dma_request_chan" return
> > the channel number or "-EPROBE_DEFER" if it's not ready.
> > But this information ("-EPROBE_DEFER") is lost in the penultimate
> function
> > "dma_request_slave_channel", which return only the chann, if all is ok,
> or
> > NULL, in case of errors.
> > So the deferral mechanism is not used.
>
> Right, yes - that analysis seems correct. The interfaces seem a bit
> weird here but fixing them looks like the most complete and robust fix.
Ok Mark, I'll fix this problem as soon as I can, using EPROBE_DEFER.
For now, in my application, I use the patch that I already sent,
with the "softdep" workaround:
MODULE_SOFTDEP("pre: dw_dmac");
I tested it a lot, with more than 2000 cold reboot (automatic
switch on/off using a controlled power supply) and it always worked good.
Thanks for your help!
Flavio
next prev parent reply other threads:[~2019-04-11 7:14 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-10 12:51 [PATCH 1/2] spi: pxa2xx: fix SCR (divisor) calculation Flavio Suligoi
2019-04-10 12:51 ` [PATCH 2/2] spi: pxa2xx: use a module softdep for dw_dmac Flavio Suligoi
2019-04-10 12:56 ` Mark Brown
2019-04-10 14:05 ` Flavio Suligoi
2019-04-10 15:28 ` Mark Brown
2019-04-11 7:14 ` Flavio Suligoi [this message]
2019-04-11 10:42 ` Mark Brown
2019-04-11 11:31 ` Flavio Suligoi
2019-04-12 8:53 ` Applied "spi: pxa2xx: use a module softdep for dw_dmac" to the spi tree Mark Brown
2019-05-02 2:19 ` Mark Brown
2019-04-11 11:55 ` [PATCH 1/2] spi: pxa2xx: fix SCR (divisor) calculation Jarkko Nikula
2019-04-11 13:10 ` Flavio Suligoi
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=7ad025c8049e4e828ce75ef1e41dcbfd@asem.it \
--to=f.suligoi@asem.it \
--cc=broonie@kernel.org \
--cc=daniel@zonque.org \
--cc=haojian.zhuang@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-spi@vger.kernel.org \
--cc=robert.jarzmik@free.fr \
/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;
as well as URLs for NNTP newsgroup(s).