From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Brezillon Subject: Re: [PATCH 1/3] of: mtd: add helper reading "nand-ecc-algo" from DT Date: Thu, 25 Feb 2016 21:09:46 +0100 Message-ID: <20160225210946.6c842f4b@bbrezillon> References: <1455300685-27009-1-git-send-email-zajec5@gmail.com> <20160224144652.14068468@bbrezillon> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= Cc: Brian Norris , "linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Kamal Dasu , Hauke Mehrtens , Rob Herring , Grant Likely , Frank Rowand List-Id: devicetree@vger.kernel.org On Thu, 25 Feb 2016 20:56:36 +0100 Rafa=C5=82 Mi=C5=82ecki wrote: > On 24 February 2016 at 14:46, Boris Brezillon > wrote: > > On Fri, 12 Feb 2016 19:11:23 +0100 > > Rafa=C5=82 Mi=C5=82ecki wrote: > > > >> This allows specifying algorithm used for NAND ECC. There are two > >> available values: "bch" and "hamming". It's important as having ju= st > >> ECC parameters (step, strength) isn't enough to determine algorith= m, > >> e.g. you can't distinct BCH-1 and Hamming. > >> > >> Signed-off-by: Rafa=C5=82 Mi=C5=82ecki > >> --- > >> Documentation/devicetree/bindings/mtd/nand.txt | 3 +++ > >> drivers/of/of_mtd.c | 33 +++++++++++++= +++++++++++++ > >> include/linux/mtd/nand.h | 5 ++++ > >> include/linux/of_mtd.h | 6 +++++ > >> 4 files changed, 47 insertions(+) > >> > >> diff --git a/Documentation/devicetree/bindings/mtd/nand.txt b/Docu= mentation/devicetree/bindings/mtd/nand.txt > >> index b53f92e..a2c2df5 100644 > >> --- a/Documentation/devicetree/bindings/mtd/nand.txt > >> +++ b/Documentation/devicetree/bindings/mtd/nand.txt > >> @@ -3,6 +3,9 @@ > >> - nand-ecc-mode : String, operation mode of the NAND ecc mode. > >> Supported values are: "none", "soft", "hw", "hw_syndrome", "hw_= oob_first", > >> "soft_bch". > >> +- nand-ecc-algo : string, algorithm of NAND ecc. > >> + Supported values are: "bch", "hamming". The defaul= t one is > >> + "bch". > > > > I like the idea of specifying which ECC algorithm should be used, a= nd > > this is IMO clearer than putting the information directly in > > nand-ecc-mode (as is already done for the "soft" and "soft_bch" mod= es, > > which are respectively encoding software hamming and software bch > > implementations). > > > > But shouldn't we take this even further and add new DT properties > > to encode the ECC layout (syndrome, oob_first), and another one to > > specify the implementation type (software or hardware)? > > > > nand-ecc-layout =3D "nornal", "syndrome" or "oob_first" > > nand-ecc-engine =3D "none", "soft" or "hw" ("on-die" ?) > > > > Note that it's not something I ask you to do right now, I just want= to > > bring the topic on the table. >=20 > So far I was fine with whatever drvier/NAND core picked, didn't have > any issue with it. If at some point we'll see a real need of > specifying it manually as well, I guess we should do as you suggested= =2E > My point is that it's kind of weird to have the same information duplicated in two different properties with possibly some conflicting configurations, like: nand-ecc-mode =3D "soft_bch"; /* software BCH implementation... */ nand-ecc-algo =3D "hamming"; /* ... and here you choose Hamming */ Of course this won't be a real problem until NAND core starts using this property to decide which soft implementation should be used, but providing a consistent binding is important IMO. --=20 Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from down.free-electrons.com ([37.187.137.238] helo=mail.free-electrons.com) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1aZ2Ey-0000E3-Tl for linux-mtd@lists.infradead.org; Thu, 25 Feb 2016 20:10:25 +0000 Date: Thu, 25 Feb 2016 21:09:46 +0100 From: Boris Brezillon To: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= Cc: Brian Norris , "linux-mtd@lists.infradead.org" , "devicetree@vger.kernel.org" , Kamal Dasu , Hauke Mehrtens , Rob Herring , Grant Likely , Frank Rowand Subject: Re: [PATCH 1/3] of: mtd: add helper reading "nand-ecc-algo" from DT Message-ID: <20160225210946.6c842f4b@bbrezillon> In-Reply-To: References: <1455300685-27009-1-git-send-email-zajec5@gmail.com> <20160224144652.14068468@bbrezillon> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 25 Feb 2016 20:56:36 +0100 Rafa=C5=82 Mi=C5=82ecki wrote: > On 24 February 2016 at 14:46, Boris Brezillon > wrote: > > On Fri, 12 Feb 2016 19:11:23 +0100 > > Rafa=C5=82 Mi=C5=82ecki wrote: > > > >> This allows specifying algorithm used for NAND ECC. There are two > >> available values: "bch" and "hamming". It's important as having just > >> ECC parameters (step, strength) isn't enough to determine algorithm, > >> e.g. you can't distinct BCH-1 and Hamming. > >> > >> Signed-off-by: Rafa=C5=82 Mi=C5=82ecki > >> --- > >> Documentation/devicetree/bindings/mtd/nand.txt | 3 +++ > >> drivers/of/of_mtd.c | 33 +++++++++++++++++= +++++++++ > >> include/linux/mtd/nand.h | 5 ++++ > >> include/linux/of_mtd.h | 6 +++++ > >> 4 files changed, 47 insertions(+) > >> > >> diff --git a/Documentation/devicetree/bindings/mtd/nand.txt b/Document= ation/devicetree/bindings/mtd/nand.txt > >> index b53f92e..a2c2df5 100644 > >> --- a/Documentation/devicetree/bindings/mtd/nand.txt > >> +++ b/Documentation/devicetree/bindings/mtd/nand.txt > >> @@ -3,6 +3,9 @@ > >> - nand-ecc-mode : String, operation mode of the NAND ecc mode. > >> Supported values are: "none", "soft", "hw", "hw_syndrome", "hw_oob_= first", > >> "soft_bch". > >> +- nand-ecc-algo : string, algorithm of NAND ecc. > >> + Supported values are: "bch", "hamming". The default on= e is > >> + "bch". > > > > I like the idea of specifying which ECC algorithm should be used, and > > this is IMO clearer than putting the information directly in > > nand-ecc-mode (as is already done for the "soft" and "soft_bch" modes, > > which are respectively encoding software hamming and software bch > > implementations). > > > > But shouldn't we take this even further and add new DT properties > > to encode the ECC layout (syndrome, oob_first), and another one to > > specify the implementation type (software or hardware)? > > > > nand-ecc-layout =3D "nornal", "syndrome" or "oob_first" > > nand-ecc-engine =3D "none", "soft" or "hw" ("on-die" ?) > > > > Note that it's not something I ask you to do right now, I just want to > > bring the topic on the table. >=20 > So far I was fine with whatever drvier/NAND core picked, didn't have > any issue with it. If at some point we'll see a real need of > specifying it manually as well, I guess we should do as you suggested. > My point is that it's kind of weird to have the same information duplicated in two different properties with possibly some conflicting configurations, like: nand-ecc-mode =3D "soft_bch"; /* software BCH implementation... */ nand-ecc-algo =3D "hamming"; /* ... and here you choose Hamming */ Of course this won't be a real problem until NAND core starts using this property to decide which soft implementation should be used, but providing a consistent binding is important IMO. --=20 Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com