Re: [PATCH] devicetree/bindings: Add binding for micron n25q512a memory

On Thu, 2014-07-03 at 23:08 -0500, Jain Priyanka-B32167 wrote:

quoted

-----Original Message-----
From: Wood Scott-B07421
Sent: Friday, July 04, 2014 3:40 AM
To: Jain Priyanka-B32167
Cc: <redacted>; <redacted>; linux-
spi@vger.kernel.org; linux-mtd@lists.infradead.org
Subject: Re: [PATCH] devicetree/bindings: Add binding for micron n25q512a
memory

On Thu, 2014-07-03 at 15:42 +0530, Priyanka Jain wrote:

quoted

-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 <redacted>
---
 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

quoted

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?

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