Re: [PATCH 2/6] mailbox/omap: add support for parsing dt devices

Hi Pavel,

quoted

quoted

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The non-DT support has to be maintained for now to not break
OMAP3 legacy boot, and the legacy-style code will be cleaned
up once OMAP3 is also converted to DT-boot only.

quoted

@@ -587,24 +606,157 @@ static int omap_mbox_unregister(struct omap_mbox_device *mdev)
 	return 0;
 }
 
+static const struct omap_mbox_device_data omap2_data = {
+	.num_users	= 4,
+	.num_fifos	= 6,
+	.intr_type	= MBOX_INTR_CFG_TYPE1,
+};
+
+static const struct omap_mbox_device_data omap3_data = {
+	.num_users	= 2,
+	.num_fifos	= 2,
+	.intr_type	= MBOX_INTR_CFG_TYPE1,
+};
+
+static const struct omap_mbox_device_data am335x_data = {
+	.num_users	= 4,
+	.num_fifos	= 8,
+	.intr_type	= MBOX_INTR_CFG_TYPE2,
+};

So you use compatible strings to look up 3 integers. Would it be better to have
num_users/num_fifos/intr_type directly in the device tree? That should be cleaner
and more flexible...

If you do that, would it be possible to have share compatible string?

Yeah, I have actually encoded the .num_users and .num_fifos in DT in the
previous version [1] with shared compatible strings, but dropped those
properties in favour of adding minimal custom properties to DT based on
some offline IRC comments. I have no objections either way, but there is
really nothing to be gained from minimizing compatible strings.

Actually, I'd guess best solution would be to do both: have it encoded
in device tree _and_ have separate compatible string for each version
(in case there are other differences). You'd still get rid of the
table...

Do note that the .intr_type has to with the register layout rather than
a physical property (mainly to distinguish the pre-OMAP4 IP register
layout), so I am not convinced that belongs to DT. This is the reason
why I didn't represent it in DT even in the previous version. The other
two are HW IP design parameters, so in general putting them in DT isn't
completely a bad idea, but I will wait to see if there are any further
comments on this from Tony or DT maintainers before I make changes.

regards
Suman