[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [RFC PATCH 2/2] xen/device-tree: Add ability to handle nodes with interrupts-extended prop




Hi, Julien





On 02/05/2019 15:13, Oleksandr Tyshchenko wrote:
From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>

Xen expects to see "interrupts" property when parsing host
device-tree. But, there are cases when some device nodes contain
"interrupts-extended" property instead.

The good example here is arch timer node for R-Car Gen3/Gen2 family,
which is mandatory device for Xen usage on ARM. And without ability
to handle such nodes, Xen fails to operate:

Per the binding documentation [1], the interrupts-extend property should only be used when a device has multiple interrupt parents. This is not the case of the arch timer, so why is it used there? Don't get me wrong, I am fine with the idea of adding "interrupts-extend". However, the commit message should give some ground why a new property has been introduced/used over the current one.

Have just grepped, looks like, R-Car Gen2/Gen3 dtsi files are not the only single users of "interrupts-extended" property for a device with a single interrupt parent...

Unfortunately, I don't know the real reason, can guess only that for a device (with a single interrupt parent) outside "/soc" container the usage of single "interrupts-extended" property is more simpler/cleaner than usage of pairs ("interrupt-parent" + "interrupts").  Looks like, the patch "ARM: dts: r8a7790: add soc node" from this series [1] started using "interrupts-extended" property for ARCH timer node. I will mention that in patch description.

I don't think it is important to know why Renesas is using it. What matter is the property allows to describe in DT a device with interrupts coming from multiple interrupt controllers.

In other words, what I ask is explaining in the commit message what this property is used for and properly a pointer to the bindings helping the reviewer to find out what you speak about.

OK. Sounds reasonable. Will add an information regarding the property itself with link. Should I retain the original sentences (regarding ARCH timer on R-Car uses it, etc) as well?





+    {
+        dt_dprintk(" intnum=%d\n", intnum);

You are re-using the exact same debug message as for "interrupts". So it would be difficult for a developer to know exactly which path is used. Could we print message regarding whether "interrupts-extended" or "interrupts" is used?

I couldn't find where else the same debug message was used, could you, please, point me? But, I don't mind to add some indicator. For "interrupts-extended" path (newly added prints) I can add the corresponding prefix...

Sorry, I thought the message was duplicated. However, I still think a message telling which property is used would be useful.

Just to clarify: should I add for the newly added messages ("interrupts-extended" path) only? Or I should modify existing messages for "interrupts" path also?


--
Regards,

Oleksandr Tyshchenko


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.