From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: Re: [PATCH v1 3/5] mtd: atmel_nand: Support PMECC on SAMA5D2 Date: Sat, 16 Jan 2016 22:05:52 -0600 Message-ID: <20160117040552.GA28704@rob-hp-laptop> References: <1452702857-2240-1-git-send-email-romain.izard.pro@gmail.com> <1452702857-2240-4-git-send-email-romain.izard.pro@gmail.com> <20160114011252.GA29778@rob-hp-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Romain Izard Cc: "Yang, Wenyou" , "linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Josh Wu , "Ferre, Nicolas" List-Id: devicetree@vger.kernel.org On Fri, Jan 15, 2016 at 09:54:07AM +0100, Romain Izard wrote: > Hi Rob, Wenyou, >=20 > 2016-01-14 14:14 GMT+01:00 Rob Herring : > > On Wed, Jan 13, 2016 at 7:17 PM, Yang, Wenyou wrote: > >> > >> > >>> -----Original Message----- > >>> From: Rob Herring [mailto:robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org] > >>> Sent: 2016=E5=B9=B41=E6=9C=8814=E6=97=A5 9:13 > >>> To: Romain Izard > >>> Cc: linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org; devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Ya= ng, Wenyou > >>> ; Josh Wu ; Ferr= e, > >>> Nicolas > >>> Subject: Re: [PATCH v1 3/5] mtd: atmel_nand: Support PMECC on SAM= A5D2 > >>> > >>> On Wed, Jan 13, 2016 at 05:34:15PM +0100, Romain Izard wrote: > >>> > Starting with the SAMA5D2, there is a new revision of the Atmel= PMECC > >>> > controller that can correct 32 bits in each sector. This contro= ller is > >>> > not 100% compatible with the previous revision that corrected a > >>> > maximum of 24 bits by sector, as some register addresses overla= p. > >>> > > >>> > Using information from the device tree, we can configure the dr= iver to > >>> > work with both versions. > >>> > > >>> > Signed-off-by: Romain Izard > >>> > --- > >>> > .../devicetree/bindings/mtd/atmel-nand.txt | 7 +++++-= - > >>> > drivers/mtd/nand/atmel_nand.c | 23 ++++++= +++++++++++++++- > >>> > drivers/mtd/nand/atmel_nand_ecc.h | 8 ++++++= -- > >>> > 3 files changed, 33 insertions(+), 5 deletions(-) > >>> > > >>> > diff --git a/Documentation/devicetree/bindings/mtd/atmel-nand.t= xt > >>> > b/Documentation/devicetree/bindings/mtd/atmel-nand.txt > >>> > index 89b0db9801b0..90887b430f03 100644 > >>> > --- a/Documentation/devicetree/bindings/mtd/atmel-nand.txt > >>> > +++ b/Documentation/devicetree/bindings/mtd/atmel-nand.txt > >>> > @@ -1,7 +1,10 @@ > >>> > Atmel NAND flash > >>> > > >>> > Required properties: > >>> > -- compatible : should be "atmel,at91rm9200-nand" or "atmel,sam= a5d4-nand". > >>> > +- compatible: The possible values are: > >>> > + "atmel,at91rm9200-nand" > >>> > + "atmel,sama5d2-nand" > >>> > + "atmel,sama5d4-nand" > >>> > - reg : should specify localbus address and size used for the = chip, > >>> > and hardware ECC controller if available. > >>> > If the hardware ECC is PMECC, it should contain address and= size for > >>> > @@ -22,7 +25,7 @@ Optional properties: > >>> > Supported values are: "none", "soft", "hw", "hw_syndrome", "= hw_oob_first", > >>> > "soft_bch". > >>> > - atmel,has-pmecc : boolean to enable Programmable Multibit EC= C hardware. > >>> > - Only supported by at91sam9x5 or later sam9 product. > >>> > + Supported by AT91SAM9x5 or later SAM9 chips, and SAMA5 chips= =2E > >>> > >>> What compatible string would AT91SAM9x5 be? > >> > >> "atmel,at91rm9200-nand". > > > > Answer the question in the binding doc by saying which compatible > > strings a property is valid for. >=20 > I'm trying to rewrite the documentation for this point, and in the en= d it > seems to me that the line should be removed instead. >=20 > Adding the 'atmel,has-pmecc' property to a SoC device tree is the nor= mal way > to describe that it supports this type of controller. If we need to w= rite it > in the documentation as well, it's a duplicate information that can b= ecome > stale quite fast, as it was before. >=20 > In the end, I believe the best path is to describe better what PMECC = is, > instead of describing as "the controller found in this kind of chip". Okay, that is important too. We are wanting to move binding=20 documentation to something more structured where we can do some amount=20 of validation of dts files against binding documentation. So that is wh= y=20 I am thinking in terms of having the information to validate a dts. But= =20 we are a ways off from doing such a thing. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html