Re: [PATCH 1/2] mtd: move code reading DT specified part probes to the common place

On Fri, 31 Mar 2017 09:42:13 +0200
Boris Brezillon [off-list ref] wrote:

Hi Rafal,

On Thu, 30 Mar 2017 23:53:31 +0200
Rafał Miłecki [off-list ref] wrote:

quoted

From: Rafał Miłecki <redacted>

Handling (creating) partitions for flash devices requires using a proper
driver that will read partition table (out of somewhere). We can't
simply try all existing drivers one by one, so MTD subsystem allows
drivers to specify a list of applicable part probes.

So far physmap_of was the only driver with support for linux,part-probe
DT property. Other ones had list or probes hardcoded which wasn't making
them really flexible. It prevented using common flash drivers on
platforms that required some specific partition table access.  

I agree that having each flash device driver specify the set of
partition parsers it supports is a bad idea (most of the time,
partition table format are devicetype agnostic). On the other hand, I'm
not a big fan of this property, and I would prefer a solution where all
parsers are tested on each MTD device.
But testing all parsers sequentially is not a perfect solution either
because it increases boot-time and you can't really define the order in
which partition parsers are tested (which means that if you have 2
different partition table in 2 different format, you can't choose the
one that has precedence on the other).

I guess I can live with this "linux,part-probe" property, even if,
as the names implies, it's not really describing hardware, and as
such, does not have its place in DT :-P.

quoted

This commit moves support for mentioned DT property to the common place
so it can be reused by other drivers.  

This property does not seem to be documented. Can you add a patch
documenting it in Documentation/devicetree/bindings/mtd/common.txt and
Cc the DT maintainers.

Please ignore this comment, it's already done in patch 2 :).

Only then we'll see if this property is
acceptable for them.

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