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authorVladimir Oltean <vladimir.oltean@nxp.com>2020-07-12 19:48:15 +0300
committerDavid S. Miller <davem@davemloft.net>2020-07-17 20:22:50 +0300
commitbba238ed037c60242332dd1e4c5778af9eba4d9b (patch)
treeeceb1b5b56f33f4cfe0d663ad363d88118158c43 /drivers/net/phy/phy_device.c
parent4291dc1a5608117439643f4fe77e4ad1827a3310 (diff)
downloadlinux-bba238ed037c60242332dd1e4c5778af9eba4d9b.tar.xz
net: phy: continue searching for C45 MMDs even if first returned ffff:ffff
At the time of introduction, in commit bdeced75b13f ("net: dsa: felix: Add PCS operations for PHYLINK"), support for the Lynx PCS inside Felix was relying, for USXGMII support, on the fact that get_phy_device() is able to parse the Lynx PCS "device-in-package" registers for this C45 MDIO device and identify it correctly. However, this was actually working somewhat by mistake (in the sense that, even though it was detected, it was detected for the wrong reasons). The get_phy_c45_ids() function works by iterating through all MMDs starting from 1 (MDIO_MMD_PMAPMD) and stops at the first one which returns a non-zero value in the "device-in-package" register pair, proceeding to see what that non-zero value is. For the Felix PCS, the first MMD (1, for the PMA/PMD) returns a non-zero value of 0xffffffff in the "device-in-package" registers. There is a code branch which is supposed to treat this case and flag it as wrong, and normally, this would have caught my attention when adding initial support for this PCS: if ((devs_in_pkg & 0x1fffffff) == 0x1fffffff) { /* If mostly Fs, there is no device there, then let's probe * MMD 0, as some 10G PHYs have zero Devices In package, * e.g. Cortina CS4315/CS4340 PHY. */ However, this code never actually kicked in, it seems, because this snippet from get_phy_c45_devs_in_pkg() was basically sabotaging itself, by returning 0xfffffffe instead of 0xffffffff: /* Bit 0 doesn't represent a device, it indicates c22 regs presence */ *devices_in_package &= ~BIT(0); Then the rest of the code just carried on thinking "ok, MMD 1 (PMA/PMD) says that there are 31 devices in that package, each having a device id of ffff:ffff, that's perfectly fine, let's go ahead and probe this PHY device". But after cleanup commit 320ed3bf9000 ("net: phy: split devices_in_package"), this got "fixed", and now devs_in_pkg is no longer 0xfffffffe, but 0xffffffff. So now, get_phy_device is returning -ENODEV for the Lynx PCS, because the semantics have remained mostly unchanged: the loop stops at the first MMD that returns a non-zero value, and that is MMD 1. But the Lynx PCS is simply a clause 37 PCS which implements the required MAC-side functionality for USXGMII (when operated in C45 mode, which is where C45 devices-in-package detection is relevant to). Of course it will fail the PMD/PMA test (MMD 1), since it is not a PHY. But it does implement detection for MDIO_MMD_PCS (3): - MDIO_DEVS1=0x008a, MDIO_DEVS2=0x0000, - MDIO_DEVID1=0x0083, MDIO_DEVID2=0xe400 Let get_phy_c45_ids() continue searching for valid MMDs, and don't assume that every phy_device has a PMA/PMD MMD implemented. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/phy/phy_device.c')
-rw-r--r--drivers/net/phy/phy_device.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 7cda95330aea..49e98a092b96 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -734,7 +734,8 @@ static int get_phy_c45_ids(struct mii_bus *bus, int addr,
/* Find first non-zero Devices In package. Device zero is reserved
* for 802.3 c45 complied PHYs, so don't probe it at first.
*/
- for (i = 1; i < MDIO_MMD_NUM && devs_in_pkg == 0; i++) {
+ for (i = 1; i < MDIO_MMD_NUM && devs_in_pkg == 0 &&
+ (devs_in_pkg & 0x1fffffff) == 0x1fffffff; i++) {
if (i == MDIO_MMD_VEND1 || i == MDIO_MMD_VEND2) {
/* Check that there is a device present at this
* address before reading the devices-in-package