From: atull <atull@opensource.altera.com>
To: Trent Piepho <tpiepho@kymetacorp.com>
Cc: Andrea Galbusera <gizero@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
"pantelis.antoniou@konsulko.com" <pantelis.antoniou@konsulko.com>,
"Moritz Fischer" <moritz.fischer@ettus.com>,
Josh Cartwright <joshc@ni.com>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"monstr@monstr.eu" <monstr@monstr.eu>,
"michal.simek@xilinx.com" <michal.simek@xilinx.com>,
Pawel Moll <pawel.moll@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
"Ian Campbell" <ijc+devicetree@hellion.org.uk>,
Kumar Gala <galak@codeaurora.org>,
Jonathan Corbet <corbet@lwn.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"delicious.quinoa@gmail.com" <delicious.quinoa@gmail.com>,
"dinguyen@opensource.altera.com" <dinguyen@opensource.altera.com>,
Matthew Gerlach <mgerlach@altera.com>
Subject: Re: [PATCH v16 6/6] ARM: socfpga: fpga bridge driver support
Date: Mon, 1 Aug 2016 09:07:34 -0500 [thread overview]
Message-ID: <alpine.DEB.2.02.1608010907110.2521@linuxheads99> (raw)
In-Reply-To: <1469737696.30803.152.camel@rtred1test09.kymeta.local>
On Thu, 28 Jul 2016, Trent Piepho wrote:
> On Thu, 2016-07-28 at 10:21 -0500, atull wrote:
> > > >
> > > > This isn't going work if more than one bridge is used. Each bridge has
> > > > its own priv and thus priv->l3_remap_value. Each bridge's priv will
> > > > have just the bit for it's own remap set. The 2nd bridge to be enabled
> > > > will turn off the 1st bridge when it re-write the l3 register.
> > >
> > > I can confirm this is exactly what happens with tag
> > > "rel_socfpga-4.1.22-ltsi_16.06.02_pr" of socfpga-4.1.22-ltsi branch
> > > from altera-opensource/linux-socfpga which includes more or less the
> > > code in this patch. If you have 2 bridges (lw-hps2fpga and hps2fpga)
> > > you end up with only one of them being visible. Easily spot by logging
> > > l3_remap_value being passed to regmap_write()...
> > >
> >
> > Anatolij kindly provided a patch for this issue. I'll push it
> > to my github repo when I can.
>
> I still think a better solution would be to allow the syscon driver
> manage shared access. The purpose of syscon is to manage access to a
> shared resource from multiple devices. And regmap already has the
> ability to cache a write-only register and allow thread safe access to
> modify bits in said register. The problem is just the pain of trying to
> do anything to syscon DT bindings. Something like "write-only" in the
> syscon binding that sets a couple values in the regmap_config is all
> that's necessary.
>
> Might as well not use syscon at all and have the bridge driver map the
> l3regs itself, since it doesn't really use syscon for anything.
>
I agree. Just need time to do it.
Alan
next prev parent reply other threads:[~2016-08-01 14:13 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-05 21:29 [PATCH v16 0/6] Device Tree support for FPGA programming atull
2016-02-05 21:29 ` [PATCH v16 1/6] fpga: add bindings document for fpga region atull
2016-02-05 22:44 ` Josh Cartwright
2016-02-07 1:16 ` atull
2016-02-22 2:54 ` Rob Herring
2016-02-05 21:29 ` [PATCH v16 2/6] add sysfs document for fpga bridge class atull
2016-02-05 21:30 ` [PATCH v16 3/6] ARM: socfpga: add bindings document for fpga bridge drivers atull
2016-02-05 21:30 ` [PATCH v16 4/6] fpga: add fpga bridge framework atull
2016-02-05 21:30 ` [PATCH v16 5/6] fpga: fpga-region: device tree control for FPGA atull
2016-02-05 21:30 ` [PATCH v16 6/6] ARM: socfpga: fpga bridge driver support atull
2016-06-10 2:18 ` Trent Piepho
2016-06-13 19:35 ` atull
2016-06-14 21:00 ` Trent Piepho
2016-07-28 10:28 ` Andrea Galbusera
2016-07-28 15:21 ` atull
2016-07-28 20:26 ` Trent Piepho
2016-08-01 14:07 ` atull [this message]
2016-02-11 20:49 ` [PATCH v16 0/6] Device Tree support for FPGA programming atull
2016-02-11 21:22 ` Rob Herring
2016-02-11 22:08 ` atull
2016-02-11 22:17 ` atull
2016-02-15 17:40 ` Moritz Fischer
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