Messages in this thread | | | Date | Tue, 26 May 2020 00:09:46 +0100 | From | Russell King - ARM Linux admin <> | Subject | Re: [RFC 04/11] net: phy: Handle c22 regs presence better |
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On Mon, May 25, 2020 at 05:22:07PM -0500, Jeremy Linton wrote: > On 5/25/20 5:01 PM, Russell King - ARM Linux admin wrote: > > On Mon, May 25, 2020 at 04:51:16PM -0500, Jeremy Linton wrote: > > > Hi, > > > > > > On 5/25/20 5:06 AM, Russell King - ARM Linux admin wrote: > > > > On Sun, May 24, 2020 at 10:34:13PM -0500, Jeremy Linton wrote: > > > > > Hi, > > > > > > > > > > On 5/23/20 1:37 PM, Russell King - ARM Linux admin wrote: > > > > > > On Fri, May 22, 2020 at 04:30:52PM -0500, Jeremy Linton wrote: > > > > > > > Until this point, we have been sanitizing the c22 > > > > > > > regs presence bit out of all the MMD device lists. > > > > > > > This is incorrect as it causes the 0xFFFFFFFF checks > > > > > > > to incorrectly fail. Further, it turns out that we > > > > > > > want to utilize this flag to make a determination that > > > > > > > there is actually a phy at this location and we should > > > > > > > be accessing it using c22. > > > > > > > > > > > > > > Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> > > > > > > > --- > > > > > > > drivers/net/phy/phy_device.c | 16 +++++++++++++--- > > > > > > > 1 file changed, 13 insertions(+), 3 deletions(-) > > > > > > > > > > > > > > diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c > > > > > > > index f0761fa5e40b..2d677490ecab 100644 > > > > > > > --- a/drivers/net/phy/phy_device.c > > > > > > > +++ b/drivers/net/phy/phy_device.c > > > > > > > @@ -689,9 +689,6 @@ static int get_phy_c45_devs_in_pkg(struct mii_bus *bus, int addr, int dev_addr, > > > > > > > return -EIO; > > > > > > > *devices_in_package |= phy_reg; > > > > > > > - /* Bit 0 doesn't represent a device, it indicates c22 regs presence */ > > > > > > > - *devices_in_package &= ~BIT(0); > > > > > > > - > > > > > > > return 0; > > > > > > > } > > > > > > > @@ -742,6 +739,8 @@ static int get_phy_c45_ids(struct mii_bus *bus, int addr, u32 *phy_id, > > > > > > > int i; > > > > > > > const int num_ids = ARRAY_SIZE(c45_ids->device_ids); > > > > > > > u32 *devs = &c45_ids->devices_in_package; > > > > > > > + bool c22_present = false; > > > > > > > + bool valid_id = false; > > > > > > > /* Find first non-zero Devices In package. Device zero is reserved > > > > > > > * for 802.3 c45 complied PHYs, so don't probe it at first. > > > > > > > @@ -770,6 +769,10 @@ static int get_phy_c45_ids(struct mii_bus *bus, int addr, u32 *phy_id, > > > > > > > return 0; > > > > > > > } > > > > > > > + /* Bit 0 doesn't represent a device, it indicates c22 regs presence */ > > > > > > > + c22_present = *devs & BIT(0); > > > > > > > + *devs &= ~BIT(0); > > > > > > > + > > > > > > > /* Now probe Device Identifiers for each device present. */ > > > > > > > for (i = 1; i < num_ids; i++) { > > > > > > > if (!(c45_ids->devices_in_package & (1 << i))) > > > > > > > @@ -778,6 +781,13 @@ static int get_phy_c45_ids(struct mii_bus *bus, int addr, u32 *phy_id, > > > > > > > ret = _get_phy_id(bus, addr, i, &c45_ids->device_ids[i], true); > > > > > > > if (ret < 0) > > > > > > > return ret; > > > > > > > + if (valid_phy_id(c45_ids->device_ids[i])) > > > > > > > + valid_id = true; > > > > > > > > > > > > Here you are using your "devices in package" validator to validate the > > > > > > PHY ID value. One of the things it does is mask this value with > > > > > > 0x1fffffff. That means you lose some of the vendor OUI. To me, this > > > > > > looks completely wrong. > > > > > > > > > > I think in this case I was just using it like the comment in > > > > > get_phy_device() "if the phy_id is mostly F's, there is no device here". > > > > > > > > > > My understanding is that the code is trying to avoid the 0xFFFFFFFF returns > > > > > that seem to indicate "bus ok, phy didn't respond". > > > > > > > > > > I just checked the OUI registration, and while there are a couple OUI's > > > > > registered that have a number of FFF's in them, none of those cases seems to > > > > > overlap sufficiently to cause this to throw them out. Plus a phy would also > > > > > have to have model+revision set to 'F's. So while might be possible, if > > > > > unlikely, at the moment I think the OUI registration keeps this from being a > > > > > problem. Particularly, if i'm reading the mapping correctly, the OUI mapping > > > > > guarantees that the field cannot be all '1's due to the OUI having X & M > > > > > bits cleared. It sort of looks like the mapping is trying to lose those > > > > > bits, by tossing bit 1 & 2, but the X & M are in the wrong octet (AFAIK, I > > > > > just read it three times cause it didn't make any sense). > > > > > > > > I should also note that we have at least one supported PHY where one > > > > of the MMDs returns 0xfffe for even numbered registers and 0x0000 for > > > > odd numbered registers in one of the vendor MMDs for addresses 0 > > > > through 0xefff - which has a bit set in the devices-in-package. > > > > > > > > It also returns 0x0082 for almost every register in MMD 2, but MMD 2's > > > > devices-in-package bit is clear in most of the valid MMDs, so we > > > > shouldn't touch it. > > > > > > > > These reveal the problem of randomly probing MMDs - they can return > > > > unexpected values and not be as well behaved as we would like them to > > > > be. Using register 8 to detect presence may be beneficial, but that > > > > may also introduce problems as we haven't used that before (and we > > > > don't know whether any PHY that wrong.) I know at least the 88x3310 > > > > gets it right for all except the vendor MMDs, where the low addresses > > > > appear non-confromant to the 802.3 specs. Both vendor MMDs are > > > > definitely implemented, just not with anything conforming to 802.3. > > > > > > Yes, we know even for the NXP reference hardware, one of the phy's doesn't > > > probe out correctly because it doesn't respond to the ieee defined > > > registers. I think at this point, there really isn't anything we can do > > > about that unless we involve the (ACPI) firmware in currently nonstandard > > > behaviors. > > > > > > So, my goals here have been to first, not break anything, and then do a > > > slightly better job finding phy's that are (mostly?) responding correctly to > > > the 802.3 spec. So we can say "if you hardware is ACPI conformant, and you > > > have IEEE conformant phy's you should be ok". So, for your example phy, I > > > guess the immediate answer is "use DT" or "find a conformant phy", or even > > > "abstract it in the firmware and use a mailbox interface". > > > > You haven't understood. The PHY does conform for most of the MMDs, > > but there are a number that do not conform. > > Probably... > > Except that i'm not sure how that is a problem at the moment, its still > going to trigger as a found phy, and walk the same mmd list as before > requesting drivers. Those drivers haven't changed their behavior so where is > the problem? If there is a problem its in 7/11 where things are getting > kicked due to seemingly invalid Ids. > > The 1/11 devices=0 case actually appears to be a bug i'm fixing because you > won't get an ID or a MMD list from that (before or after).
I think I've just flattened that argument in my immediately preceding reply on the Cortina situation; I think you've grossly misread that through not fully researching the history and then finding the existing users.
There is no bug that you are fixing from what I can see.
-- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC for 0.8m (est. 1762m) line in suburbia: sync at 13.1Mbps down 424kbps up
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