On Mon, 2014-07-07 at 23:41 -0500, Jain Priyanka-B32167 wrote: > > > -----Original Message----- > > From: Wood Scott-B07421 > > Sent: Tuesday, July 08, 2014 2:56 AM > > To: Jain Priyanka-B32167 > > Cc: devicetree@xxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx; linux- > > spi@xxxxxxxxxxxxxxx; linux-mtd@xxxxxxxxxxxxxxxxxxx > > Subject: Re: [PATCH] devicetree/bindings: Add binding for micron n25q512a > > memory > > > > On Thu, 2014-07-03 at 23:08 -0500, Jain Priyanka-B32167 wrote: > > > > > > > -----Original Message----- > > > > From: Wood Scott-B07421 > > > > Sent: Friday, July 04, 2014 3:40 AM > > > > To: Jain Priyanka-B32167 > > > > Cc: devicetree@xxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx; > > > > linux- spi@xxxxxxxxxxxxxxx; linux-mtd@xxxxxxxxxxxxxxxxxxx > > > > Subject: Re: [PATCH] devicetree/bindings: Add binding for micron > > > > n25q512a memory > > > > > > > > On Thu, 2014-07-03 at 15:42 +0530, Priyanka Jain wrote: > > > > > -Micron n25q512a memory is supported by m25p80 driver. > > > > > Add compatible field required to support n25q512a in m25p80.txt > > > > > -Add micron to the vendor-prefixes.txt file > > > > > > > > > > Signed-off-by: Priyanka Jain <Priyanka.Jain@xxxxxxxxxxxxx> > > > > > --- > > > > > Documentation/devicetree/bindings/mtd/m25p80.txt | 1 + > > > > > .../devicetree/bindings/vendor-prefixes.txt | 1 + > > > > > 2 files changed, 2 insertions(+), 0 deletions(-) > > > > > > > > Why did you send this to the ppc list but not the spi or mtd lists? > > > > > > > [Jain Priyanka-B32167] Sorry, I missed that > > > > I'm having a hard time following the flow of how these SPI devices > > > > get bound -- is the compatible involved at all? I don't see this > > > > string (with vendor prefix included) in the driver. I do see a > > > > table that contains what looks like device IDs. If the device can > > > > report its id, shouldn't we rely on that rather than device tree > > compatible? > > > > > > > > -Scott > > > [Jain Priyanka-B32167] > > > Spi driver has a check to device name corresponding to device-id and > > compare to what is passed in dts string. > > > > Please go into more detail. I don't see where the string > > "micron,n25q512a" appears in the current kernel. I do see "n25q512a", > > but how does that compare successfully with the version of the string > > that has a vendor compatible? > > > > Again, is there a device ID that can be read at runtime? Is there a > > compatible string that represents a common programming interface? > [Jain Priyanka-B32167] > > Spi driver (of_register_spi_devices()) search for compatible string in > device-tree. It selects the flash device driver based on the compatible > string (n25q512a). This compatible string is essential, else device > probe wont continue. Then Device-id of flash is read at runtime in > probe and compared with the corresponding device-id of flash > (n25q512a). Device-id (maintained as first element in INFO string in > spi_nor_ids[] in drivers/mtd/spi-nor/spi-nor.c file) By "device id" I'm talking about 0x20bb20, not "n25q512a". Where does that come from? > Only if both device-ids match, the device is taken as successfully > detected. Regarding vendor "micron", you are right currently the vendor > information is not maintained as such in device-id, but the convention > that is followed for compatible string is "vendor-id, device-id" Is there going to be a patch to the driver to accept the string with vendor id? > > > New checkpatch script search for exact string match in binding folder. > > So, I have added this in example. > > > > That check has a lot of false positives when it comes to compatible > > strings for specific chips that don't need to be specifically mentioned > > in a more generic binding. > > > > -Scott > > > [Jain Priyanka-B32167] Even though "micron,n25q512a" is in sync with > binding mentioned in " > Documentation/devicetree/bindings/mtd/m25p80.txt ", I have to add > this as an a example, just to avoid checkpatch error. What should be > the approach going forward: Should such checkpatch warnings be ignored? They shouldn't be ignored nor blindly remedied. You should look at the message and decide whether a binding is needed and whether it is present. There probably should be a binding here, but I don't have enough information to say whether it should be specific to n25q512a or if spi nor can be described more generically. -Scott -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
