linux-kernel - Re: [RFC PATCH] edac: zynq: Added EDAC support for zynq ddr ecc controller

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Message-ID: <e76556b4-c6c1-470d-bcd9-4b01b4e9e517@TX2EHSMHS028.ehs.local>
Date:	Wed, 12 Mar 2014 09:13:44 -0700
From:	Sören Brinkmann <soren.brinkmann@...inx.com>
To:	Michal Simek <michal.simek@...inx.com>
CC:	Michal Simek <monstr@...str.eu>,
	Mark Rutland <mark.rutland@....com>,
	Punnaiah Choudary Kalluri 
	<punnaiah.choudary.kalluri@...inx.com>,
	"dougthompson@...ssion.com" <dougthompson@...ssion.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	Pawel Moll <Pawel.Moll@....com>,
	"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
	"galak@...eaurora.org" <galak@...eaurora.org>,
	"rob@...dley.net" <rob@...dley.net>,
	"kpc528@...il.com" <kpc528@...il.com>,
	"kalluripunnaiahchoudary@...il.com" 
	<kalluripunnaiahchoudary@...il.com>,
	"punnaia@...inx.com" <punnaia@...inx.com>
Subject: Re: [RFC PATCH] edac: zynq: Added EDAC support for zynq ddr ecc
 controller

On Wed, 2014-03-12 at 11:27AM +0100, Michal Simek wrote:
> On 03/11/2014 04:50 PM, Sören Brinkmann wrote:
> > On Tue, 2014-03-11 at 09:32AM +0100, Michal Simek wrote:
> >> On 03/10/2014 11:32 PM, Sören Brinkmann wrote:
> >>> On Mon, 2014-03-10 at 12:58PM +0100, Michal Simek wrote:
> >>>> On 03/10/2014 11:56 AM, Mark Rutland wrote:
> >>>>> On Sun, Mar 09, 2014 at 02:57:16AM +0000, Punnaiah Choudary Kalluri wrote:
> >>>>>> Added EDAC support for reporting the ecc errors of zynq ddr controller.
> >>>>>> The ddr ecc controller corrects single bit errors and detects double bit
> >>>>>> errors
> >>>>>>
> >>>>>> Signed-off-by: Punnaiah Choudary Kalluri <punnaia@...inx.com>
> >>>>>> ---
> >>>>>>  .../devicetree/bindings/edac/zynq_edac.txt         |   18 +
> >>>>>>  drivers/edac/Kconfig                               |    7 +
> >>>>>>  drivers/edac/Makefile                              |    1 +
> >>>>>>  drivers/edac/zynq_edac.c                           |  613 ++++++++++++++++++++
> >>>>>>  4 files changed, 639 insertions(+), 0 deletions(-)
> >>>>>>  create mode 100644 Documentation/devicetree/bindings/edac/zynq_edac.txt
> >>>>>>  create mode 100644 drivers/edac/zynq_edac.c
> >>>>>>
> >>>>>> diff --git a/Documentation/devicetree/bindings/edac/zynq_edac.txt b/Documentation/devicetree/bindings/edac/zynq_edac.txt
> >>>>>> new file mode 100644
> >>>>>> index 0000000..c21ff83
> >>>>>> --- /dev/null
> >>>>>> +++ b/Documentation/devicetree/bindings/edac/zynq_edac.txt
> >>>>>> @@ -0,0 +1,18 @@
> >>>>>> +Zynq EDAC driver, it does reports the DDR ECC single bit errors that are
> >>>>>> +corrected and double bit ecc errors that are detected by the DDR ECC controller.
> >>>>>> +ECC support for DDR is available in half-bus width(16 bit) configuration only.
> >>>>>> +
> >>>>>> +Required properties:
> >>>>>> +- compatible: Should be "xlnx,ps7-ddrc" or "xlnx,ps7-ddrc-1.00.a"
> >>>>>
> >>>>> Is this an or or a xor?
> >>>>
> >>>> Compatible string should be just xlnx,zynq-ddrc-1.00.a.
> >>>> Nothing with ps7.
> >>>
> >>> Isn't this vendor IP? IMHO, this should be something completely
> >>> different. Or if you want some Zynq-specific compat string it should
> >>> refer to an actual version string associated with Zynq. 1.00.a is not,
> >>> AFAIK.
> >>
> >> I have checked with Punnaiah that this is Synopsys DDR memory controller.
> >> Zynq is based on 1.4 version with some customization.
> >> It means I think reasonable solution is
> >> call it drivers/edac/synopsys_edac.c
> >> rename zynq_ in driver to synopsys_ and
> >> use xlnx,zynq-ddrc-1.00.a compatible string because zynq is not using
> >> clean synopsys version.
> >>
> >> I am not getting point why you don't like 1.00.a suffix here.
> >> Because of historical point of view compatible strings should be different
> >> for early silicon, silicon v1, silicon v2, silicon v3, etc
> >> but we haven't used it at all that's why we can use xilinx scheme
> >> which we are using for our soft IPs.
> > 
> > Well, but you refer to Zynq which has silicon revisions you can use to
> > refer to a specific Zynq version. That matches data sheets. Zynq-1.00.a
> > is just completely made up and wouldn't be found in any data sheet.
> 
> I didn't reply this one but we discussed this with Soren over phone.
> No problem to use Synopsys version A07 according TRM.
> 
> Then compatible string is
> xlnx,zynq-ddrc-A07 and file name is synopsys_edac.c

This seems to make sense. I'm never sure whether leading zeros are
actually needed and tend to remove them, but in general this looks like
a reasonable string to identify Zynq's DDR controller.

	Sören


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