From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

Update the RZN1 A5PSW driver to obtain the DSA tag protocol from
device-specific data instead of using a hard-coded value. Add a new
`tag_proto` field to `struct a5psw_of_data` and use it in
`a5psw_get_tag_protocol()` to return the appropriate protocol for
each SoC.

This allows future SoCs such as RZ/T2H and RZ/N2H, which use the
DSA_TAG_PROTO_RZT2H_ETHSW tag format, to share the same driver
infrastructure without code duplication.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
 drivers/net/dsa/rzn1_a5psw.c | 5 ++++-
 drivers/net/dsa/rzn1_a5psw.h | 2 ++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/rzn1_a5psw.c b/drivers/net/dsa/rzn1_a5psw.c
index d957b6d40f05..dc42a409eaef 100644
--- a/drivers/net/dsa/rzn1_a5psw.c
+++ b/drivers/net/dsa/rzn1_a5psw.c
@@ -97,7 +97,9 @@ static enum dsa_tag_protocol a5psw_get_tag_protocol(struct dsa_switch *ds,
 						    int port,
 						    enum dsa_tag_protocol mp)
 {
-	return DSA_TAG_PROTO_RZN1_A5PSW;
+	struct a5psw *a5psw = ds->priv;
+
+	return a5psw->of_data->tag_proto;
 }
 
 static void a5psw_port_pattern_set(struct a5psw *a5psw, int port, int pattern,
@@ -1316,6 +1318,7 @@ static void a5psw_shutdown(struct platform_device *pdev)
 static const struct a5psw_of_data rzn1_of_data = {
 	.nports = 5,
 	.cpu_port = 4,
+	.tag_proto = DSA_TAG_PROTO_RZN1_A5PSW,
 };
 
 static const struct of_device_id a5psw_of_mtable[] = {
diff --git a/drivers/net/dsa/rzn1_a5psw.h b/drivers/net/dsa/rzn1_a5psw.h
index d1b2cc5b43e6..0fef32451e4f 100644
--- a/drivers/net/dsa/rzn1_a5psw.h
+++ b/drivers/net/dsa/rzn1_a5psw.h
@@ -234,10 +234,12 @@ union lk_data {
  * struct a5psw_of_data - OF data structure
  * @nports: Number of ports in the switch
  * @cpu_port: CPU port number
+ * @tag_proto: DSA tag protocol used by the switch
  */
 struct a5psw_of_data {
 	unsigned int nports;
 	unsigned int cpu_port;
+	enum dsa_tag_protocol tag_proto;
 };
 
 /**
-- 
2.52.0

On Fri, Nov 21, 2025 at 11:35:34AM +0000, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> 
> Update the RZN1 A5PSW driver to obtain the DSA tag protocol from
> device-specific data instead of using a hard-coded value. Add a new
> `tag_proto` field to `struct a5psw_of_data` and use it in
> `a5psw_get_tag_protocol()` to return the appropriate protocol for
> each SoC.
> 
> This allows future SoCs such as RZ/T2H and RZ/N2H, which use the
> DSA_TAG_PROTO_RZT2H_ETHSW tag format, to share the same driver
> infrastructure without code duplication.

Again the twitching when reading the commit title. I thought this has
something to do with the "dsa-tag-protocol" property from
Documentation/devicetree/bindings/net/dsa/dsa-port.yaml. The tagger *is*
runtime-configurable if you implement the ds->ops->change_tag_protocol()
API, and it's also possible to trigger that API function from OF
properties. But this is not what the patch does, so it is confusing.

I think it would be more natural to say "choose tagging protocol based
on compatible string".

> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> ---

Anyway I'm not reviewing this commit until the reason why you added a
new name for this tagger becomes completely clear.

Hi Vladimir,

Thank you for the review.

On Fri, Nov 21, 2025 at 8:55 PM Vladimir Oltean <olteanv@gmail.com> wrote:
>
> On Fri, Nov 21, 2025 at 11:35:34AM +0000, Prabhakar wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> >
> > Update the RZN1 A5PSW driver to obtain the DSA tag protocol from
> > device-specific data instead of using a hard-coded value. Add a new
> > `tag_proto` field to `struct a5psw_of_data` and use it in
> > `a5psw_get_tag_protocol()` to return the appropriate protocol for
> > each SoC.
> >
> > This allows future SoCs such as RZ/T2H and RZ/N2H, which use the
> > DSA_TAG_PROTO_RZT2H_ETHSW tag format, to share the same driver
> > infrastructure without code duplication.
>
> Again the twitching when reading the commit title. I thought this has
> something to do with the "dsa-tag-protocol" property from
> Documentation/devicetree/bindings/net/dsa/dsa-port.yaml. The tagger *is*
> runtime-configurable if you implement the ds->ops->change_tag_protocol()
> API, and it's also possible to trigger that API function from OF
> properties. But this is not what the patch does, so it is confusing.
>
> I think it would be more natural to say "choose tagging protocol based
> on compatible string".
>
Ok, I will update the commit message in v2.

> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > ---
>
> Anyway I'm not reviewing this commit until the reason why you added a
> new name for this tagger becomes completely clear.
As discussed in patch 2/11 the format fields vary, so this change is
needed to support the new SoC.

Cheers,
Prabhakar