From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>,
Vinod Koul <vinod.koul@intel.com>,
linux-kernel@vger.kernel.org,
spear-devel <spear-devel@list.st.com>
Subject: Re: [PATCH] dw_dmac: adjust slave_id accordingly to request line base
Date: Wed, 30 Jan 2013 09:32:56 +0200 [thread overview]
Message-ID: <1359531176.31148.46.camel@smile> (raw)
In-Reply-To: <CAOh2x=nTJ1iz9aoR8VrkE5A+iaLMMbvFeebGPsO8KWRpDLw7=A@mail.gmail.com>
On Tue, 2013-01-29 at 20:57 +0530, Viresh Kumar wrote:
> On Tue, Jan 29, 2013 at 10:52 AM, Mika Westerberg
> <mika.westerberg@linux.intel.com> wrote:
> > We had a discusssion about this with Andy as well. The thing is that there
> > is no way in current resource to pass DMA request line numbers supported by
> > the controller to the driver in a generic way. We on the other hand have to
> > deal this somehow as we have a shared DMA controller on Lynxpoint where the
> > offset will start from 16 (but it might be something else as well).
> >
> > Is there something which limits the usage of IORESOUCE_DMA to be only
> > usable for ISA DMA channels?
>
> Andy,
>
> Why do we need this request_line_base? Why not program the actual value
> directly into the slave structure (base + offset)?
Slave device exactly has knowledge about this number slave_id = (base
+offset). However...
> In case it is required, add it in platform data field or can add DT
> binding for it.
We get a device from the ACPI CSRT table. During enumeration we don't
know what kind of the device it is. From the enumeration point of view
each device enumerated from CSRT is a platform device (see
drivers/acpi/csrt.c for the details).
That's why we have to pass this info somehow to the DMAC driver. And
like Mika already mentioned we have no other generic way except
IORESOURCE_DMA. If you have something better in mind, please share. We
could adopt our code then.
--
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy
next prev parent reply other threads:[~2013-01-30 7:33 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-28 11:04 [PATCH] dw_dmac: adjust slave_id accordingly to request line base Andy Shevchenko
2013-01-29 4:59 ` Viresh Kumar
2013-01-29 5:22 ` Mika Westerberg
2013-01-29 15:27 ` Viresh Kumar
2013-01-30 7:32 ` Andy Shevchenko [this message]
2013-01-30 8:01 ` Viresh Kumar
2013-01-30 8:07 ` Andy Shevchenko
2013-02-07 13:22 ` Shevchenko, Andriy
2013-02-12 15:56 ` Vinod Koul
2013-02-12 16:34 ` Andy Shevchenko
2013-02-12 15:53 ` Vinod Koul
2013-02-12 16:43 ` Mika Westerberg
2013-02-12 17:34 ` Vinod Koul
2013-02-12 19:02 ` Mika Westerberg
2013-02-14 9:57 ` Vinod Koul
2013-02-14 10:17 ` Mika Westerberg
2013-02-07 13:28 ` Viresh Kumar
2013-02-19 9:02 ` Andy Shevchenko
2013-02-19 22:17 ` Rafael J. Wysocki
2013-02-20 6:04 ` Vinod Koul
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