This adds a function to set the PCS only if there is not one currently
set. The intention here is to allow MAC drivers to have a "default" PCS
(such as an internal one) which may be used when one has not been set
via the device tree. This allows for backwards compatibility for cases
where a PCS was automatically attached if necessary.
Signed-off-by: Sean Anderson <[email protected]>
---
drivers/net/phy/phylink.c | 26 ++++++++++++++++++++++++++
include/linux/phylink.h | 1 +
2 files changed, 27 insertions(+)
diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 046fdac3597d..f82dc0f87f40 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -871,6 +871,32 @@ int phylink_set_pcs(struct phylink *pl, struct phylink_pcs *pcs)
}
EXPORT_SYMBOL_GPL(phylink_set_pcs);
+/**
+ * phylink_set_pcs_weak() - optionally set the current PCS for phylink to use
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ * @pcs: a pointer to the &struct phylink_pcs
+ *
+ * Bind the MAC PCS to phylink only if there is no currently-bound PCS. This
+ * may be called to set a "default" PCS, such as an internal PCS which was
+ * previously handled by the MAC driver directly. Otherwise, this function
+ * behaves like phylink_set_pcs();
+ *
+ * Context: may sleep.
+ * Return: 1 if the PCS was set, 0 if it was not, or -errno on failure.
+ */
+int phylink_set_pcs_weak(struct phylink *pl, struct phylink_pcs *pcs)
+{
+ int ret;
+
+ if (!pl->pcs) {
+ ret = phylink_set_pcs(pl, pcs);
+ return ret ? ret : 1;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(phylink_set_pcs_weak);
+
static struct phylink_pcs *phylink_find_pcs(struct fwnode_handle *fwnode)
{
struct phylink_pcs *pcs;
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index d60756b36ad3..bd0ce707d098 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -442,6 +442,7 @@ void pcs_link_up(struct phylink_pcs *pcs, unsigned int mode,
int phylink_register_pcs(struct phylink_pcs *pcs);
void phylink_unregister_pcs(struct phylink_pcs *pcs);
int phylink_set_pcs(struct phylink *pl, struct phylink_pcs *pcs);
+int phylink_set_pcs_weak(struct phylink *pl, struct phylink_pcs *pcs);
struct phylink *phylink_create(struct phylink_config *, struct fwnode_handle *,
phy_interface_t iface,
--
2.25.1
On Mon, Oct 04, 2021 at 03:15:17PM -0400, Sean Anderson wrote:
> This adds a function to set the PCS only if there is not one currently
> set. The intention here is to allow MAC drivers to have a "default" PCS
> (such as an internal one) which may be used when one has not been set
> via the device tree. This allows for backwards compatibility for cases
> where a PCS was automatically attached if necessary.
I'm not sure I entirely like this approach. Why can't the network
driver check for the pcs-handle property and avoid using its
"default" if present?
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
On Tue, Oct 05, 2021 at 10:51:38AM +0100, Russell King (Oracle) wrote:
> On Mon, Oct 04, 2021 at 03:15:17PM -0400, Sean Anderson wrote:
> > This adds a function to set the PCS only if there is not one currently
> > set. The intention here is to allow MAC drivers to have a "default" PCS
> > (such as an internal one) which may be used when one has not been set
> > via the device tree. This allows for backwards compatibility for cases
> > where a PCS was automatically attached if necessary.
>
> I'm not sure I entirely like this approach. Why can't the network
> driver check for the pcs-handle property and avoid using its
> "default" if present?
And that would also be in line with
ethernet/freescale/dpaa2/dpaa2-mac.c: node = fwnode_find_reference(dpmac_node, "pcs-handle", 0);
We need a uniform meaning of pcs-handle. And dpaa2-mac.c has set the
precedent that the MAC uses it, not phylink. That can however be
changed, if it make sense, but both users should do the same.
Andrew
On 10/5/21 9:43 AM, Andrew Lunn wrote:
> On Tue, Oct 05, 2021 at 10:51:38AM +0100, Russell King (Oracle) wrote:
>> On Mon, Oct 04, 2021 at 03:15:17PM -0400, Sean Anderson wrote:
>> > This adds a function to set the PCS only if there is not one currently
>> > set. The intention here is to allow MAC drivers to have a "default" PCS
>> > (such as an internal one) which may be used when one has not been set
>> > via the device tree. This allows for backwards compatibility for cases
>> > where a PCS was automatically attached if necessary.
>>
>> I'm not sure I entirely like this approach. Why can't the network
>> driver check for the pcs-handle property and avoid using its
>> "default" if present?
>
> And that would also be in line with
>
> ethernet/freescale/dpaa2/dpaa2-mac.c: node = fwnode_find_reference(dpmac_node, "pcs-handle", 0);
>
> We need a uniform meaning of pcs-handle. And dpaa2-mac.c has set the
> precedent that the MAC uses it, not phylink. That can however be
> changed, if it make sense, but both users should do the same.
The tricky bit here happens when drivers set the PCS in mac_prepare()
depending on the interface. So you have to remember during probe()
whether you are supposed to set the PCS for later. I would like to leave
more of this to phylink to ensure that the process is done in a uniform
way.
--Sean