Re: [PATCH V2 01/10] Documentation: dt-bindings: mailbox: tegra: Add binding for HSP mailbox

From: Stephen Warren
Date: Mon Jul 11 2016 - 12:08:18 EST

On 07/11/2016 08:14 AM, Rob Herring wrote:
On Thu, Jul 07, 2016 at 12:35:02PM -0600, Stephen Warren wrote:
On 07/07/2016 12:13 PM, Sivaram Nair wrote:
On Tue, Jul 05, 2016 at 05:04:22PM +0800, Joseph Lo wrote:
Add DT binding for the Hardware Synchronization Primitives (HSP). The
HSP is designed for the processors to share resources and communicate
together. It provides a set of hardware synchronization primitives for
interprocessor communication. So the interprocessor communication (IPC)
protocols can use hardware synchronization primitive, when operating
between two processors not in an SMP relationship.

diff --git a/include/dt-bindings/mailbox/tegra186-hsp.h b/include/dt-bindings/mailbox/tegra186-hsp.h

+#define HSP_MBOX_TYPE_DB 0x0
+#define HSP_MBOX_TYPE_SM 0x1
+#define HSP_MBOX_TYPE_SS 0x2
+#define HSP_MBOX_TYPE_AS 0x3
+
+#define HSP_DB_MASTER_CCPLEX 17
+#define HSP_DB_MASTER_BPMP 19
+
+#define HSP_MBOX_ID(type, ID) \
+ (HSP_MBOX_TYPE_##type << 16 | ID)

It will be nicer if you avoid the macro glue magic '##' for 'type'. I
would also suggest to use braces around 'type' and 'ID'.

This technique been used without issue in quite a few other places without
issue, and has the benefit of simplifying the text wherever the macro is
used. What issue do you foresee?

I'm not a fan of using the macros to begin with and less so anything
more complex than a single constant value. I'd rather see 2 cells here
with the first being the id and the 2nd being the type.

An issue with token pasting is grepping for DB, SM, etc. in kernel tree
is probably noisy. Not such a big deal here, but a major PIA when you
have more complex sets of includes.

Is that a NAK or simply a suggestion? Having a single cell makes DT parsing a bit simpler, since pretty much every SW stack provides a default "one-cell" of_xlate implementation, whereas >1 cell means custom code for of_xlate.