Re: [PATCH v3 RFC 4/4] net: dsa: hsr: Provide generic HSR ksz_hsr_{join|leave} functions

[Vladimir Oltean <olteanv@gmail.com>]

On Mon, Sep 04, 2023 at 02:02:09PM +0200, Lukasz Majewski wrote:
> This patch provides the common KSZ (i.e. Microchip) DSA code with support
> for HSR aware devices.
> 
> To be more specific - generic ksz_hsr_{join|leave} functions are provided,
> now only supporting KSZ9477 IC.
> 
> Signed-off-by: Lukasz Majewski <lukma@denx.de>
> ---
> Changes for v2:
> - None
> 
> Changes for v3:
> - Do not return -EOPNOTSUPP for only PRP_V1 (as v2 will not be caught)

Should be squashed into patch 3/4. The split does not make the code
easier to review for me.

> ---
>  drivers/net/dsa/microchip/ksz_common.c | 69 ++++++++++++++++++++++++++
>  1 file changed, 69 insertions(+)
> 
> diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
> index 579fde54d1e1..91d1acaf4494 100644
> --- a/drivers/net/dsa/microchip/ksz_common.c
> +++ b/drivers/net/dsa/microchip/ksz_common.c
> @@ -16,6 +16,7 @@
>  #include <linux/etherdevice.h>
>  #include <linux/if_bridge.h>
>  #include <linux/if_vlan.h>
> +#include <linux/if_hsr.h>
>  #include <linux/irq.h>
>  #include <linux/irqdomain.h>
>  #include <linux/of_mdio.h>
> @@ -3433,6 +3434,72 @@ u16 ksz_hsr_get_ports(struct dsa_switch *ds)
>  	return 0;
>  }
>  
> +static int ksz_hsr_join(struct dsa_switch *ds, int port, struct net_device *hsr)
> +{
> +	struct dsa_port *partner = NULL, *dp;
> +	struct ksz_device *dev = ds->priv;
> +	enum hsr_version ver;
> +	int ret;
> +
> +	ret = hsr_get_version(hsr, &ver);
> +	if (ret)
> +		return ret;
> +
> +	switch (dev->chip_id) {
> +	case KSZ9477_CHIP_ID:
> +		if (!(ver == HSR_V0 || ver == HSR_V1))
> +			return -EOPNOTSUPP;

move the "default: return -EOPNOTSUPP" statement from below here.

> +	}

I don't see any restriction to allow offloading a single HSR device.
Looking at patch 3/4, that will obviously not work due to some hardware
registers which are global and would be overwritten by the second HSR
device.

For example, a5psw_port_bridge_join() has a similar restriction to
offload a single bridge device.

If you return -EOPNOTSUPP, then DSA should fall back to an unoffloaded,
100% software-based HSR device, and that should work too. It would be
good if you could verify that the unoffloaded HSR works well after the
changes too.

> +
> +	/* We can't enable redundancy on the switch until both
> +	 * redundant ports have signed up.
> +	 */
> +	dsa_hsr_foreach_port(dp, ds, hsr) {
> +		if (dp->index != port) {
> +			partner = dp;
> +			break;
> +		}
> +	}
> +
> +	if (!partner)
> +		return 0;
> +
> +	switch (dev->chip_id) {
> +	case KSZ9477_CHIP_ID:
> +		return ksz9477_hsr_join(ds, port, hsr, partner);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
> +}
> +
> +static int ksz_hsr_leave(struct dsa_switch *ds, int port,
> +			 struct net_device *hsr)
> +{
> +	struct dsa_port *partner = NULL, *dp;
> +	struct ksz_device *dev = ds->priv;
> +
> +	dsa_hsr_foreach_port(dp, ds, hsr) {
> +		if (dp->index != port) {
> +			partner = dp;
> +			break;
> +		}
> +	}
> +
> +	if (!partner)
> +		return 0;
> +
> +	switch (dev->chip_id) {
> +	case KSZ9477_CHIP_ID:
> +		return ksz9477_hsr_leave(ds, port, hsr, partner);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
> +}
> +
>  static const struct dsa_switch_ops ksz_switch_ops = {
>  	.get_tag_protocol	= ksz_get_tag_protocol,
>  	.connect_tag_protocol   = ksz_connect_tag_protocol,
> @@ -3452,6 +3519,8 @@ static const struct dsa_switch_ops ksz_switch_ops = {
>  	.get_sset_count		= ksz_sset_count,
>  	.port_bridge_join	= ksz_port_bridge_join,
>  	.port_bridge_leave	= ksz_port_bridge_leave,
> +	.port_hsr_join		= ksz_hsr_join,
> +	.port_hsr_leave		= ksz_hsr_leave,
>  	.port_stp_state_set	= ksz_port_stp_state_set,
>  	.port_pre_bridge_flags	= ksz_port_pre_bridge_flags,
>  	.port_bridge_flags	= ksz_port_bridge_flags,
> -- 
> 2.20.1
>