From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ezequiel Garcia Subject: Re: [PATCH 3/3] mtd: spi-nand: add devicetree binding Date: Thu, 8 Jan 2015 12:12:20 -0300 Message-ID: <54AE9E54.2010506@imgtec.com> References: <87F60714EC601C4C83DFF1D2E3D390A04AB425@NTXXIAMBX02.xacn.micron.com> <54ADF66F.7090400@imgtec.com> <87F60714EC601C4C83DFF1D2E3D390A04AB4EA@NTXXIAMBX02.xacn.micron.com> Mime-Version: 1.0 Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <87F60714EC601C4C83DFF1D2E3D390A04AB4EA@NTXXIAMBX02.xacn.micron.com> Sender: linux-kernel-owner@vger.kernel.org To: =?gbk?Q?=22Peter_Pan_=C5=CB=B6=B0_=28peterpandong=29=22?= , "robh+dt@kernel.org" , "pawel.moll@arm.com" , "mark.rutland@arm.com" , "ijc+devicetree@hellion.org.uk" , "galak@codeaurora.org" , "dwmw2@infradead.org" , Brian Norris Cc: "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , =?gbk?Q?=22Qi_Wang_=CD=F5=C6=F0_=28qiwang=29=22?= , =?gbk?Q?=22Frank_Liu_=C1=F5=C8=BA_=28frankliu=29=22?= , =?gbk?Q?=22Melanie_Zhang_=D5=C5=D1=E0_=28me?= =?gbk?Q?laniezhang=29=22?= List-Id: devicetree@vger.kernel.org On 01/08/2015 02:04 AM, Peter Pan =C5=CB=B6=B0 (peterpandong) wrote: >>> This commit adds the devicetree binding document that specifies the >>> spi nand devices support. >>> >>> Signed-off-by: Peter Pan >>> --- >>> Documentation/devicetree/bindings/mtd/spi-nand.txt | 22 >> ++++++++++++++++++++++ >>> 1 file changed, 22 insertions(+) >>> create mode 100644 Documentation/devicetree/bindings/mtd/spi- >> nand.txt >>> >>> diff --git a/Documentation/devicetree/bindings/mtd/spi-nand.txt >> b/Documentation/devicetree/bindings/mtd/spi-nand.txt >>> new file mode 100644 >>> index 0000000..9dd3efd >>> --- /dev/null >>> +++ b/Documentation/devicetree/bindings/mtd/spi-nand.txt >>> @@ -0,0 +1,22 @@ >>> +* NAND driver for MT29F, GD5F and similar SPI NAND flash chips >>> + >>> +Required properties: >>> +- #address-cells, #size-cells : Must be present if the device has >> sub-nodes >>> + representing partitions. >>> +- compatible : Should be the manufacturer and the name of the chip= =2E >> Bear in mind >>> >> >> Unless I'm mistaken, we don't need the chip ID here, as SPI NAND all= ows >> to autodetect the device. Any reason why we can't just use a generic >> compatible "spi-nand" here? >> -- >> Ezequiel >=20 > In fact, I don't know how to autodetect the SPI NAND device. Micron d= evice and > Gigadevice device have different read ID functions. The Chip ID here = is used to > determine which function to use. >=20 Isn't the difference between the Read ID very minor? One of the vendor needs a 2-byte ID read, and the other one needs a 3-byte ID read. So you can just try with 2-byte, and if that fails (no vendor ID is found on the first byte), you can try with the 3-byte command. It's not the most elegant solution, but it's not super awful either. --=20 Ezequiel