From: Sergei Shtylyov <sshtylyov@ru•mvista.com>
To: Grant Likely <grant.likely@secretlab•ca>
Cc: linuxppc-dev@ozlabs•org, John Linn <john.linn@xilinx•com>
Subject: Re: [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart 16550.
Date: Sat, 22 Mar 2008 19:40:01 +0300 [thread overview]
Message-ID: <47E53661.9010508@ru.mvista.com> (raw)
In-Reply-To: <fa686aa40803220806w3288ab8ew754404a5aee152cf@mail.gmail.com>
Grant Likely wrote:
>> > Personally, I'm not fond of this approach. There is already some
>> > traction to using the reg-shift property to specify spacing, and I
>> > think it would be appropriate to also define a reg-offset property to
>> > handle the +3 offset and then let the xilinx 16550 nodes use those.
>> That's making things only worse than the mere "reg-shift" idea. I think
>> that both are totally wrong. Everything about the programming interface should
>> be said in the "compatible" and possibly "model" properties. of_serial driver
>> should recognize them and pass the necessary details to 8250.c. As for me, I'm
>> strongly against plaguing the device tree with the *Linux driver
>> implementation specifics* (despite I was trying this with MTD -- there it
>> seemed somewhat more grounded :-).
> Not true. Compatible defines what the node is describing. It is
> perfectly valid for a compatible value definition to also defines some
> additional properties that can be queried for interface details.
> Xilinx is completely free to define a "xlnx,..." compatible value for
> their ns16550 compatible device. However, 'sparse' ns16550 devices
> are a common and well known variation so I think it is valid and
> reasonable to define a compatible binding for this case.
We have been mostly talking about the 16550-compatible devices which
external circuitry makes "sparse" so far. This is surely not a property of a
16550 device to be "sparse" or not, although some say that this doesn't
matter. :-)
> As for using a new binding like "sparse16550" instead of extending
That "sparse16550" again... what if it's a superset of 16550 (not an
uncommon case too), will you also define "sparce16650", "sparse16570", and so
on? :-)
> "ns16550"; it is because reg-shift and reg-offset would be required
> nodes and therefore is not compatible with drivers using the original
> ns16550 binding. Using a new namespace gives freedom to define the
> required properties.
You'll have to define several namespaces I'm afraid...
> Cheers,
> g.
WBR, Sergei
next prev parent reply other threads:[~2008-03-22 16:38 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <12060242324116-git-send-email-john.linn@xilinx.com>
2008-03-20 14:43 ` [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart 16550 John Linn
2008-03-21 0:19 ` Grant Likely
2008-03-21 9:21 ` Paul Mackerras
2008-03-21 11:39 ` Segher Boessenkool
2008-03-21 16:08 ` [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart16550 Stephen Neuendorffer
2008-03-21 16:48 ` Segher Boessenkool
2008-03-22 14:50 ` [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart 16550 Grant Likely
2008-03-22 16:06 ` Sergei Shtylyov
2008-03-24 14:09 ` Sergei Shtylyov
2008-03-24 14:27 ` Grant Likely
2008-03-24 16:15 ` Sergei Shtylyov
2008-03-24 16:48 ` Grant Likely
2008-03-24 17:03 ` Sergei Shtylyov
2008-03-25 22:48 ` John Linn
2008-03-21 13:00 ` Sergei Shtylyov
2008-03-21 15:37 ` Segher Boessenkool
2008-03-21 15:54 ` Sergei Shtylyov
2008-03-21 16:45 ` Segher Boessenkool
2008-03-21 16:50 ` [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart16550 Stephen Neuendorffer
2008-03-21 17:01 ` [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart 16550 Sergei Shtylyov
2008-03-22 15:06 ` Grant Likely
2008-03-22 16:40 ` Sergei Shtylyov [this message]
2008-03-21 16:14 ` [PATCH 2/3] [POWERPC] Xilinx: of_serial support for Xilinx uart16550 Stephen Neuendorffer
[not found] ` <1206024232655-git-send-email-john.linn@xilinx.com>
2008-03-20 14:43 ` [PATCH 3/3] [POWERPC] Xilinx: boot support for Xilinx uart 16550 John Linn
2008-03-20 14:54 ` Grant Likely
2008-03-20 16:15 ` John Linn
2008-03-20 21:18 ` Grant Likely
[not found] ` <20080320175601.5D86217C8055@mail127-sin.bigfish.com>
2008-03-20 21:07 ` Grant Likely
2008-03-20 22:04 ` Grant Likely
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