From: Philipp Zabel <p.zabel@pengutronix.de>
To: Moritz Fischer <moritz.fischer@ettus.com>
Cc: iztok.jeras@redpitaya.com, linux-kernel@vger.kernel.org
Subject: Re: Reset implementation for Zynq
Date: Mon, 24 Oct 2016 11:00:05 +0200 [thread overview]
Message-ID: <1477299605.2446.11.camel@pengutronix.de> (raw)
In-Reply-To: <20161021170438.GA4307@live.com>
Hi Iztok, Moritz,
Am Freitag, den 21.10.2016, 10:04 -0700 schrieb Moritz Fischer:
> Iztok,
>
> On Fri, Oct 21, 2016 at 03:08:47AM -0700, iztok.jeras@redpitaya.com wrote:
> > Hi Moritz,
> >
> > I was looking at your reset implementation for Zynq:
> > https://github.com/Xilinx/linux-xlnx/blob/629041605b93343ad2e8971ceaac3edcef0b043b/drivers/reset/reset-zynq.c
> > I went through related mailing list posts (including earlier versions of the patch) so I kind of understand what to change in the device tree.
>
> Please look at the upstream kernel sources and use the mailing list
> (lkml) if you want to report bugs. Xilinx' vendor tree might or might
> not be up to date.
>
> > I would like to use this driver to reset the Zynq I2C controller, since we have trouble with it getting into a lock up state.
> > I plan to use function device_reset_optional() from:
> > https://github.com/Xilinx/linux-xlnx/blob/629041605b93343ad2e8971ceaac3edcef0b043b/include/linux/reset.h
> >
> > But this function is calling the reset function pointer from the reset_control_ops structure.
> > For the zynq driver this function pointer is not defined, only assert, deassert and status are.
> >
> > Is this a missing implementation, or is there a default implementation (I did not find one) which which performs an assert+deassert,
> > or is there another set of reset APIs I should use inside the kernel.
>
> You could just call reset_control_assert() and reset_control_deassert().
> You're right there is currently no implementation for the 'reset' function for
> zynq (and most of the other SoCs). I'll need to see if it makes sense at
> all.
The implementation of reset_control_reset in software really only makes
sense if the reset provider driver knows about the necessary delays for
all reset consumers.
> Please note that you'd probably have to modify the i2c driver to
> integrate reset functionality cleanly.
>
> Thanks,
>
> Moritz
regards
Philipp
next prev parent reply other threads:[~2016-10-24 9:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20161021030847.6b4c15d01df5508dab02973c2a5944d9.645b3cfd21.mailapi@email21.godaddy.com>
2016-10-21 17:04 ` Reset implementation for Zynq Moritz Fischer
2016-10-24 9:00 ` Philipp Zabel [this message]
2016-10-24 17:03 ` Moritz Fischer
2016-11-08 6:34 ` Shubhrajyoti Datta
[not found] ` <20161108024052.6b4c15d01df5508dab02973c2a5944d9.803a60fc5b.mailapi@email21.godaddy.com>
2016-11-08 11:56 ` Shubhrajyoti Datta
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