> -----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) 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" > > > 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? ��.n��������+%������w��{.n����z�{��ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f