macb: probe of 10090000.ethernet failed with error -110

macb: probe of 10090000.ethernet failed with error -110

[Atish Patra]

Hi,
I am not able to connect to the network on HiFiveUnleashed board (4/5 
times) because of the following error. I believe the error is due to 
device Microsemi VSC8541 which is enabled CONFIG_MICROSEMI_PHY.

----------------------------------------------------------------------
macb 10090000.ethernet (unnamed net_device) (uninitialized): Could not 
attach to PHY
macb: probe of 10090000.ethernet failed with error -110
----------------------------------------------------------------------

I have all the sifive specific drivers built on top of 4.17. It works 
sometimes. My initial debugging points to following code path.

macb_probe->phy_connect_direct->phy_attach_direct->phy_init_hw()->
genphy_soft_reset()->phy_poll_reset

phy_poll_reset tries to do reset PHY by clearing the BMCR_RESET.

int phy_init_hw(struct phy_device *phydev)
{
         int ret = 0;

         /* Deassert the reset signal */
         phy_device_reset(phydev, 0);

         if (!phydev->drv || !phydev->drv->config_init)
                 return 0;

         if (phydev->drv->soft_reset)
                 ret = phydev->drv->soft_reset(phydev);
         else
                 ret = genphy_soft_reset(phydev);

    ...
}

static int phy_poll_reset(struct phy_device *phydev)
{
         /* Poll until the reset bit clears (50ms per retry == 0.6 sec) */
         unsigned int retries = 12;
         int ret;

         dump_stack();
         do {
                 msleep(50);
                 ret = phy_read(phydev, MII_BMCR);
                 if (ret < 0)
                         return ret;
         } while (ret & BMCR_RESET && --retries);
         if (ret & BMCR_RESET)
                 return -ETIMEDOUT;

         /* Some chips (smsc911x) may still need up to another 1ms after the
          * BMCR_RESET bit is cleared before they are usable.
          */
         msleep(1);
         return 0;
}

It looks like genphy_soft_reset()->phy_poll_reset() timesout after 
trying out 0.6 seconds returning -ETIMEDOUT. I have tried to increase 
the timeout to 20 seconds. Still same timeout happens. I have verified 
the driver is getting registered.

[    5.960025] libphy: Microsemi VSC8541 SyncE: Registered new driver
[    6.455635] libphy: phy_init_hw: In phydev->drv name =[Microsemi 
VSC8541 SyncE]

Has anybody seen this error earlier or know what can be possible reason 
for the timeout?


Regards,
Atish

macb: probe of 10090000.ethernet failed with error -110

[Atish Patra]

On 8/24/18 10:18 AM, Atish Patra wrote:
> Hi,
> I am not able to connect to the network on HiFiveUnleashed board (4/5
> times) because of the following error. I believe the error is due to
> device Microsemi VSC8541 which is enabled CONFIG_MICROSEMI_PHY.
> 
> ----------------------------------------------------------------------
> macb 10090000.ethernet (unnamed net_device) (uninitialized): Could not
> attach to PHY
> macb: probe of 10090000.ethernet failed with error -110
> ----------------------------------------------------------------------
> 
> I have all the sifive specific drivers built on top of 4.17. It works
> sometimes. My initial debugging points to following code path.
> 
> macb_probe->phy_connect_direct->phy_attach_direct->phy_init_hw()->
> genphy_soft_reset()->phy_poll_reset
> 
> phy_poll_reset tries to do reset PHY by clearing the BMCR_RESET.
> 
> int phy_init_hw(struct phy_device *phydev)
> {
>           int ret = 0;
> 
>           /* Deassert the reset signal */
>           phy_device_reset(phydev, 0);
> 
>           if (!phydev->drv || !phydev->drv->config_init)
>                   return 0;
> 
>           if (phydev->drv->soft_reset)
>                   ret = phydev->drv->soft_reset(phydev);
>           else
>                   ret = genphy_soft_reset(phydev);
> 
>      ...
> }
> 
> static int phy_poll_reset(struct phy_device *phydev)
> {
>           /* Poll until the reset bit clears (50ms per retry == 0.6 sec) */
>           unsigned int retries = 12;
>           int ret;
> 
>           dump_stack();
>           do {
>                   msleep(50);
>                   ret = phy_read(phydev, MII_BMCR);
>                   if (ret < 0)
>                           return ret;
>           } while (ret & BMCR_RESET && --retries);
>           if (ret & BMCR_RESET)
>                   return -ETIMEDOUT;
> 
>           /* Some chips (smsc911x) may still need up to another 1ms after the
>            * BMCR_RESET bit is cleared before they are usable.
>            */
>           msleep(1);
>           return 0;
> }
> 
> It looks like genphy_soft_reset()->phy_poll_reset() timesout after
> trying out 0.6 seconds returning -ETIMEDOUT. I have tried to increase
> the timeout to 20 seconds. Still same timeout happens. I have verified
> the driver is getting registered.
> 
> [    5.960025] libphy: Microsemi VSC8541 SyncE: Registered new driver
> [    6.455635] libphy: phy_init_hw: In phydev->drv name =[Microsemi
> VSC8541 SyncE]
> 
> Has anybody seen this error earlier or know what can be possible reason
> for the timeout?
> 
> 
> Regards,
> Atish
> 

Here is probable cause for this issue and a temporary fix.
FYI: I am no networking expert. So the following analysis and fix might 
be completely stupid and outrageous.

The HighFive Unleashed board contains Microsemi 8541 PHY.
Here is the spec: 
https://www.mouser.com/ds/2/523/Microsemi_VSC8541-01_Datasheet_10496_V40-1148034.pdf

As per the spec, the PHY needs to be reset twice. However, 4.15 kernel 
did not have support for that. Thus, FSBL code in Unleashed is hacked to 
resolve it by resetting twice in their code (Thanks to Palmer for the 
hint).

It looks like that kernel driver now supports resetting the signal one 
additional time. As it had been  already reset twice in FSBL, PHY gets 
into incorrect state causing error mentioned in the below mail.

The following simple HACK brings up networking in 4.19rc2 without any 
issues.

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 98f4b1f7..02c31f83 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -64,9 +64,6 @@ static int mdiobus_register_gpiod(struct mdio_device 
*mdiodev)

         mdiodev->reset = gpiod;

-       /* Assert the reset signal again */
-       mdio_device_reset(mdiodev, 1);

         return 0;
  }

The following upstream commit introduced the correct resetting of PHY 
devices.

commit bafbdd52
Author: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Date:   Mon Dec 4 13:35:05 2017 +0100

     phylib: Add device reset GPIO support


This fix proposed here is just a hack and should not merged into 
upstream code. Ideally, the fix should be done in FSBL code. Until, we 
have that from SiFive, this hack can be used as a temporary solution for 
anybody facing the same networking problem.


Regards,
Atish

Re: macb: probe of 10090000.ethernet failed with error -110

[Andreas Schwab]

On Sep 14 2018, Atish Patra <atish.patra@wdc.com> wrote:

> This fix proposed here is just a hack and should not merged into upstream
> code. Ideally, the fix should be done in FSBL code.

So what should that be?  I tried removing the second reset in the FSBL
code, but that didn't change anything.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

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macb: probe of 10090000.ethernet failed with error -110

[Andreas Schwab]

The PHY probing of the macb driver appears to be rather unreliable.
Most of the time it doesn't work the first time, I have to reload the
module several times to let it succeed.

[   40.530000] macb: GEM doesn't support hardware ptp.
[   40.530000] libphy: MACB_mii_bus: probed
[   41.450000] macb 10090000.ethernet (unnamed net_device) (uninitialized): Could not attach to PHY
[   41.510000] macb: probe of 10090000.ethernet failed with error -110
[ 1354.400000] macb: GEM doesn't support hardware ptp.
[ 1354.410000] libphy: MACB_mii_bus: probed
[ 1355.260000] macb 10090000.ethernet (unnamed net_device) (uninitialized): Could not attach to PHY
[ 1355.300000] macb: probe of 10090000.ethernet failed with error -110
[ 1358.100000] macb: GEM doesn't support hardware ptp.
[ 1358.110000] libphy: MACB_mii_bus: probed
[ 1358.310000] Microsemi VSC8541 SyncE 10090000.ethernet-ffffffff:00: attached PHY driver [Microsemi VSC8541 SyncE] (mii_bus:phy_addr=10090000.ethernet-ffffffff:00, irq=POLL)
[ 1358.320000] macb 10090000.ethernet eth0: Cadence GEM rev 0x10070109 at 0x10090000 irq 12 (70:b3:d5:92:f1:07)

This is 4.20-rc4 on a HiFive-U.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab at suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

macb: probe of 10090000.ethernet failed with error -110

[Andreas Schwab]

The PHY probing of the macb driver appears to be rather unreliable.
Most of the time it doesn't work the first time, I have to reload the
module several times to let it succeed.

[   40.530000] macb: GEM doesn't support hardware ptp.
[   40.530000] libphy: MACB_mii_bus: probed
[   41.450000] macb 10090000.ethernet (unnamed net_device) (uninitialized): Could not attach to PHY
[   41.510000] macb: probe of 10090000.ethernet failed with error -110
[ 1354.400000] macb: GEM doesn't support hardware ptp.
[ 1354.410000] libphy: MACB_mii_bus: probed
[ 1355.260000] macb 10090000.ethernet (unnamed net_device) (uninitialized): Could not attach to PHY
[ 1355.300000] macb: probe of 10090000.ethernet failed with error -110
[ 1358.100000] macb: GEM doesn't support hardware ptp.
[ 1358.110000] libphy: MACB_mii_bus: probed
[ 1358.310000] Microsemi VSC8541 SyncE 10090000.ethernet-ffffffff:00: attached PHY driver [Microsemi VSC8541 SyncE] (mii_bus:phy_addr=10090000.ethernet-ffffffff:00, irq=POLL)
[ 1358.320000] macb 10090000.ethernet eth0: Cadence GEM rev 0x10070109 at 0x10090000 irq 12 (70:b3:d5:92:f1:07)

This is 4.20-rc4 on a HiFive-U.

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

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macb: probe of 10090000.ethernet failed with error -110

[Atish Patra]

On 11/28/18 2:11 AM, Andreas Schwab wrote:
> The PHY probing of the macb driver appears to be rather unreliable.
> Most of the time it doesn't work the first time, I have to reload the
> module several times to let it succeed.
> 
> [   40.530000] macb: GEM doesn't support hardware ptp.
> [   40.530000] libphy: MACB_mii_bus: probed
> [   41.450000] macb 10090000.ethernet (unnamed net_device) (uninitialized): Could not attach to PHY
> [   41.510000] macb: probe of 10090000.ethernet failed with error -110
> [ 1354.400000] macb: GEM doesn't support hardware ptp.
> [ 1354.410000] libphy: MACB_mii_bus: probed
> [ 1355.260000] macb 10090000.ethernet (unnamed net_device) (uninitialized): Could not attach to PHY
> [ 1355.300000] macb: probe of 10090000.ethernet failed with error -110
> [ 1358.100000] macb: GEM doesn't support hardware ptp.
> [ 1358.110000] libphy: MACB_mii_bus: probed
> [ 1358.310000] Microsemi VSC8541 SyncE 10090000.ethernet-ffffffff:00: attached PHY driver [Microsemi VSC8541 SyncE] (mii_bus:phy_addr=10090000.ethernet-ffffffff:00, irq=POLL)
> [ 1358.320000] macb 10090000.ethernet eth0: Cadence GEM rev 0x10070109 at 0x10090000 irq 12 (70:b3:d5:92:f1:07)
> 
> This is 4.20-rc4 on a HiFive-U.
> 
> Andreas.
> 

Here is my previous analysis on the issue.
http://lists.infradead.org/pipermail/linux-riscv/2018-September/001503.html

Not sure if you have tried the hack already. But here it is anyways.
https://github.com/atishp04/riscv-linux/commit/aa230e7dc2ab01db5b630f427e57297ffc25c884


Regards,
Atish

Re: macb: probe of 10090000.ethernet failed with error -110

[Atish Patra]

On 11/28/18 2:11 AM, Andreas Schwab wrote:
> The PHY probing of the macb driver appears to be rather unreliable.
> Most of the time it doesn't work the first time, I have to reload the
> module several times to let it succeed.
> 
> [   40.530000] macb: GEM doesn't support hardware ptp.
> [   40.530000] libphy: MACB_mii_bus: probed
> [   41.450000] macb 10090000.ethernet (unnamed net_device) (uninitialized): Could not attach to PHY
> [   41.510000] macb: probe of 10090000.ethernet failed with error -110
> [ 1354.400000] macb: GEM doesn't support hardware ptp.
> [ 1354.410000] libphy: MACB_mii_bus: probed
> [ 1355.260000] macb 10090000.ethernet (unnamed net_device) (uninitialized): Could not attach to PHY
> [ 1355.300000] macb: probe of 10090000.ethernet failed with error -110
> [ 1358.100000] macb: GEM doesn't support hardware ptp.
> [ 1358.110000] libphy: MACB_mii_bus: probed
> [ 1358.310000] Microsemi VSC8541 SyncE 10090000.ethernet-ffffffff:00: attached PHY driver [Microsemi VSC8541 SyncE] (mii_bus:phy_addr=10090000.ethernet-ffffffff:00, irq=POLL)
> [ 1358.320000] macb 10090000.ethernet eth0: Cadence GEM rev 0x10070109 at 0x10090000 irq 12 (70:b3:d5:92:f1:07)
> 
> This is 4.20-rc4 on a HiFive-U.
> 
> Andreas.
> 

Here is my previous analysis on the issue.
http://lists.infradead.org/pipermail/linux-riscv/2018-September/001503.html

Not sure if you have tried the hack already. But here it is anyways.
https://github.com/atishp04/riscv-linux/commit/aa230e7dc2ab01db5b630f427e57297ffc25c884


Regards,
Atish

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macb: probe of 10090000.ethernet failed with error -110

[Florian Fainelli]

+Andrew, Heiner,

On 11/28/18 10:15 AM, Atish Patra wrote:
> On 11/28/18 2:11 AM, Andreas Schwab wrote:
>> The PHY probing of the macb driver appears to be rather unreliable.
>> Most of the time it doesn't work the first time, I have to reload the
>> module several times to let it succeed.
>>
>> [?? 40.530000] macb: GEM doesn't support hardware ptp.
>> [?? 40.530000] libphy: MACB_mii_bus: probed
>> [?? 41.450000] macb 10090000.ethernet (unnamed net_device)
>> (uninitialized): Could not attach to PHY
>> [?? 41.510000] macb: probe of 10090000.ethernet failed with error -110
>> [ 1354.400000] macb: GEM doesn't support hardware ptp.
>> [ 1354.410000] libphy: MACB_mii_bus: probed
>> [ 1355.260000] macb 10090000.ethernet (unnamed net_device)
>> (uninitialized): Could not attach to PHY
>> [ 1355.300000] macb: probe of 10090000.ethernet failed with error -110
>> [ 1358.100000] macb: GEM doesn't support hardware ptp.
>> [ 1358.110000] libphy: MACB_mii_bus: probed
>> [ 1358.310000] Microsemi VSC8541 SyncE 10090000.ethernet-ffffffff:00:
>> attached PHY driver [Microsemi VSC8541 SyncE]
>> (mii_bus:phy_addr=10090000.ethernet-ffffffff:00, irq=POLL)
>> [ 1358.320000] macb 10090000.ethernet eth0: Cadence GEM rev 0x10070109
>> at 0x10090000 irq 12 (70:b3:d5:92:f1:07)
>>
>> This is 4.20-rc4 on a HiFive-U.
>>
>> Andreas.
>>
> 
> Here is my previous analysis on the issue.
> http://lists.infradead.org/pipermail/linux-riscv/2018-September/001503.html
> 
> Not sure if you have tried the hack already. But here it is anyways.
> https://github.com/atishp04/riscv-linux/commit/aa230e7dc2ab01db5b630f427e57297ffc25c884

Andrew and I were discussing about this and we would recommend that you
localize the workaround within the Vitesse PHY driver and within the
driver's probe function. In order to avoid a chicken and egg problem
though, you might have to change the PHY's compatible string in the
Device Tree to include its PHY OUI, e.g:

compatible = "ethernet-phy-1234.5678" which will force the OF layer
registering MDIO/PHY devices to probe to the specific driver that
matches that PHY. Let us know if this does not work, in which case we
might have to introduce another DT property that indicate a "double
reset" is required.
-- 
Florian

Re: macb: probe of 10090000.ethernet failed with error -110

[Florian Fainelli]

+Andrew, Heiner,

On 11/28/18 10:15 AM, Atish Patra wrote:
> On 11/28/18 2:11 AM, Andreas Schwab wrote:
>> The PHY probing of the macb driver appears to be rather unreliable.
>> Most of the time it doesn't work the first time, I have to reload the
>> module several times to let it succeed.
>>
>> [   40.530000] macb: GEM doesn't support hardware ptp.
>> [   40.530000] libphy: MACB_mii_bus: probed
>> [   41.450000] macb 10090000.ethernet (unnamed net_device)
>> (uninitialized): Could not attach to PHY
>> [   41.510000] macb: probe of 10090000.ethernet failed with error -110
>> [ 1354.400000] macb: GEM doesn't support hardware ptp.
>> [ 1354.410000] libphy: MACB_mii_bus: probed
>> [ 1355.260000] macb 10090000.ethernet (unnamed net_device)
>> (uninitialized): Could not attach to PHY
>> [ 1355.300000] macb: probe of 10090000.ethernet failed with error -110
>> [ 1358.100000] macb: GEM doesn't support hardware ptp.
>> [ 1358.110000] libphy: MACB_mii_bus: probed
>> [ 1358.310000] Microsemi VSC8541 SyncE 10090000.ethernet-ffffffff:00:
>> attached PHY driver [Microsemi VSC8541 SyncE]
>> (mii_bus:phy_addr=10090000.ethernet-ffffffff:00, irq=POLL)
>> [ 1358.320000] macb 10090000.ethernet eth0: Cadence GEM rev 0x10070109
>> at 0x10090000 irq 12 (70:b3:d5:92:f1:07)
>>
>> This is 4.20-rc4 on a HiFive-U.
>>
>> Andreas.
>>
> 
> Here is my previous analysis on the issue.
> http://lists.infradead.org/pipermail/linux-riscv/2018-September/001503.html
> 
> Not sure if you have tried the hack already. But here it is anyways.
> https://github.com/atishp04/riscv-linux/commit/aa230e7dc2ab01db5b630f427e57297ffc25c884

Andrew and I were discussing about this and we would recommend that you
localize the workaround within the Vitesse PHY driver and within the
driver's probe function. In order to avoid a chicken and egg problem
though, you might have to change the PHY's compatible string in the
Device Tree to include its PHY OUI, e.g:

compatible = "ethernet-phy-1234.5678" which will force the OF layer
registering MDIO/PHY devices to probe to the specific driver that
matches that PHY. Let us know if this does not work, in which case we
might have to introduce another DT property that indicate a "double
reset" is required.
-- 
Florian

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macb: probe of 10090000.ethernet failed with error -110

[Palmer Dabbelt]

On Wed, 28 Nov 2018 13:33:47 PST (-0800), f.fainelli at gmail.com wrote:
> +Andrew, Heiner,
>
> On 11/28/18 10:15 AM, Atish Patra wrote:
>> On 11/28/18 2:11 AM, Andreas Schwab wrote:
>>> The PHY probing of the macb driver appears to be rather unreliable.
>>> Most of the time it doesn't work the first time, I have to reload the
>>> module several times to let it succeed.
>>>
>>> [?? 40.530000] macb: GEM doesn't support hardware ptp.
>>> [?? 40.530000] libphy: MACB_mii_bus: probed
>>> [?? 41.450000] macb 10090000.ethernet (unnamed net_device)
>>> (uninitialized): Could not attach to PHY
>>> [?? 41.510000] macb: probe of 10090000.ethernet failed with error -110
>>> [ 1354.400000] macb: GEM doesn't support hardware ptp.
>>> [ 1354.410000] libphy: MACB_mii_bus: probed
>>> [ 1355.260000] macb 10090000.ethernet (unnamed net_device)
>>> (uninitialized): Could not attach to PHY
>>> [ 1355.300000] macb: probe of 10090000.ethernet failed with error -110
>>> [ 1358.100000] macb: GEM doesn't support hardware ptp.
>>> [ 1358.110000] libphy: MACB_mii_bus: probed
>>> [ 1358.310000] Microsemi VSC8541 SyncE 10090000.ethernet-ffffffff:00:
>>> attached PHY driver [Microsemi VSC8541 SyncE]
>>> (mii_bus:phy_addr=10090000.ethernet-ffffffff:00, irq=POLL)
>>> [ 1358.320000] macb 10090000.ethernet eth0: Cadence GEM rev 0x10070109
>>> at 0x10090000 irq 12 (70:b3:d5:92:f1:07)
>>>
>>> This is 4.20-rc4 on a HiFive-U.
>>>
>>> Andreas.
>>>
>>
>> Here is my previous analysis on the issue.
>> http://lists.infradead.org/pipermail/linux-riscv/2018-September/001503.html
>>
>> Not sure if you have tried the hack already. But here it is anyways.
>> https://github.com/atishp04/riscv-linux/commit/aa230e7dc2ab01db5b630f427e57297ffc25c884
>
> Andrew and I were discussing about this and we would recommend that you
> localize the workaround within the Vitesse PHY driver and within the
> driver's probe function. In order to avoid a chicken and egg problem
> though, you might have to change the PHY's compatible string in the
> Device Tree to include its PHY OUI, e.g:
>
> compatible = "ethernet-phy-1234.5678" which will force the OF layer
> registering MDIO/PHY devices to probe to the specific driver that
> matches that PHY. Let us know if this does not work, in which case we
> might have to introduce another DT property that indicate a "double
> reset" is required.

If I understand what's going on correctly here, any instance of the VSC8541 phy 
has the unexpected feature where unmanaged mode is entered by following this 
particular reset sequence.  The specific wording from the datasheet is

    https://www.mouser.com/ds/2/523/Microsemi_VSC8541-01_Datasheet_10496_V40-1148034.pdf
    3.18.2 Unmanaged Applications
    To configure the device using unmanaged mode, perform the following steps:
    1. Apply power.
    2. Apply RefClk.
    3. Release reset, drive high. Power and clock must be high before releasing reset.
    Note: For unmanaged mode operation, the NRESET pin must have two rising 
          edges (logical 0-1-0-1 transition sequence) applied at this step.
    4. Wait 15 ms minimum.
    5. (Optional) For applications that gain register access to the device 
	using the management interface, steps 6?10 can then be performed in 
	order to modify default settings.

which is where the double reset sequence comes from.

For the HiFive Unleashed (a board with this phy) we perform this reset sequence 
in an early stage of the bootloader knows as the FSBL

    // VSC8541 PHY reset sequence; leave pull-down active for 2ms
    nsleep(2000000);
    // Set GPIO 12 (PHY NRESET) to OE=1 and OVAL=1
    atomic_fetch_or(&GPIO_REG(GPIO_OUTPUT_VAL), PHY_NRESET);
    atomic_fetch_or(&GPIO_REG(GPIO_OUTPUT_EN),  PHY_NRESET);
    nsleep(100);
    // Reset PHY again to enter unmanaged mode
    atomic_fetch_and(&GPIO_REG(GPIO_OUTPUT_VAL), ~PHY_NRESET);
    nsleep(100);
    atomic_fetch_or(&GPIO_REG(GPIO_OUTPUT_VAL), PHY_NRESET);
    nsleep(15000000);

which you can see here

    https://github.com/sifive/freedom-u540-c000-bootloader/blob/master/fsbl/main.c#L273

This is all fine as long as Linux doesn't go and reset the phy again. Until 
bafbdd527d56 ("phylib: Add device reset GPIO support") was the case.  After 
that commit I believe phylib is resetting the phy while attempting to enter 
unmanaged mode, which is now allowed in this particular chip.

Since it appears the phy is not usually described by the device tree but is 
instead discovered by probing a MII-based ID register, it seems the best place 
to put this is within the phy driver itself.  I find it's usually best to 
describe things with code, so I hacked up something like

    diff --git a/drivers/net/phy/mscc.c b/drivers/net/phy/mscc.c
    index 7cae17517744..8e0a71ee6bab 100644
    --- a/drivers/net/phy/mscc.c
    +++ b/drivers/net/phy/mscc.c
    @@ -1822,6 +1822,24 @@ static int vsc85xx_probe(struct phy_device *phydev)
     	return vsc85xx_dt_led_modes_get(phydev, default_mode);
     }
    
    +static int vsc8541_reset(struct phy_device *phydev, int value)
    +{
    +	WARN_ON(value != 0 || value != 1);
    +	mdio_device_reset(&phydev->mdio, value);
    +	if (value == 1) {
    +		/* The VSC8541 has an unexpected feature where a single reset
    +		 * rising edge can only be used to enter managed mode.  For
    +		 * unmanaged mode a pair of reset rising edges is necessary.
    +		 * */
    +		mdio_device_reset(&phydev_mdio, 0);
    +		mdio_device_reset(&phydev_mdio, 1);
    +
    +		/* After this pair of reset rising edges we must wait at least
    +		 * 15ms before writing any phy registers. */
    +		msleep(15);
    +	}
    +}
    +
     /* Microsemi VSC85xx PHYs */
     static struct phy_driver vsc85xx_driver[] = {
     {
    @@ -1927,6 +1945,7 @@ static struct phy_driver vsc85xx_driver[] = {
     	.get_sset_count = &vsc85xx_get_sset_count,
     	.get_strings    = &vsc85xx_get_strings,
     	.get_stats      = &vsc85xx_get_stats,
    +	.reset          = &vsc8541_reset,
     },
     {
     	.phy_id		= PHY_ID_VSC8574,
    diff --git a/include/linux/phy.h b/include/linux/phy.h
    index 3ea87f774a76..b8962ff409e8 100644
    --- a/include/linux/phy.h
    +++ b/include/linux/phy.h
    @@ -667,6 +667,10 @@ struct phy_driver {
     			    struct ethtool_tunable *tuna,
     			    const void *data);
     	int (*set_loopback)(struct phy_device *dev, bool enable);
    +
    +	/* An optional device-specific reset sequence */
    +	int (*reset)(struct phy_device *dev,
    +		     int value);
     };
     #define to_phy_driver(d) container_of(to_mdio_common_driver(d),		\
     				      struct phy_driver, mdiodrv)
    @@ -970,7 +974,10 @@ int phy_reset_after_clk_enable(struct phy_device *phydev);
    
     static inline void phy_device_reset(struct phy_device *phydev, int value)
     {
    -	mdio_device_reset(&phydev->mdio, value);
    +	if (phydev->reset)
    +		phydev->reset(phydev, value);
    +	else
    +		mdio_device_reset(&phydev->mdio, value);
     }
    
     #define phydev_err(_phydev, format, args...)	\

Note that I haven't even compiled this, and that msleep() is almost certainly 
garbage.

Am I missing something?

Re: macb: probe of 10090000.ethernet failed with error -110

[Palmer Dabbelt]

On Wed, 28 Nov 2018 13:33:47 PST (-0800), f.fainelli@gmail.com wrote:
> +Andrew, Heiner,
>
> On 11/28/18 10:15 AM, Atish Patra wrote:
>> On 11/28/18 2:11 AM, Andreas Schwab wrote:
>>> The PHY probing of the macb driver appears to be rather unreliable.
>>> Most of the time it doesn't work the first time, I have to reload the
>>> module several times to let it succeed.
>>>
>>> [   40.530000] macb: GEM doesn't support hardware ptp.
>>> [   40.530000] libphy: MACB_mii_bus: probed
>>> [   41.450000] macb 10090000.ethernet (unnamed net_device)
>>> (uninitialized): Could not attach to PHY
>>> [   41.510000] macb: probe of 10090000.ethernet failed with error -110
>>> [ 1354.400000] macb: GEM doesn't support hardware ptp.
>>> [ 1354.410000] libphy: MACB_mii_bus: probed
>>> [ 1355.260000] macb 10090000.ethernet (unnamed net_device)
>>> (uninitialized): Could not attach to PHY
>>> [ 1355.300000] macb: probe of 10090000.ethernet failed with error -110
>>> [ 1358.100000] macb: GEM doesn't support hardware ptp.
>>> [ 1358.110000] libphy: MACB_mii_bus: probed
>>> [ 1358.310000] Microsemi VSC8541 SyncE 10090000.ethernet-ffffffff:00:
>>> attached PHY driver [Microsemi VSC8541 SyncE]
>>> (mii_bus:phy_addr=10090000.ethernet-ffffffff:00, irq=POLL)
>>> [ 1358.320000] macb 10090000.ethernet eth0: Cadence GEM rev 0x10070109
>>> at 0x10090000 irq 12 (70:b3:d5:92:f1:07)
>>>
>>> This is 4.20-rc4 on a HiFive-U.
>>>
>>> Andreas.
>>>
>>
>> Here is my previous analysis on the issue.
>> http://lists.infradead.org/pipermail/linux-riscv/2018-September/001503.html
>>
>> Not sure if you have tried the hack already. But here it is anyways.
>> https://github.com/atishp04/riscv-linux/commit/aa230e7dc2ab01db5b630f427e57297ffc25c884
>
> Andrew and I were discussing about this and we would recommend that you
> localize the workaround within the Vitesse PHY driver and within the
> driver's probe function. In order to avoid a chicken and egg problem
> though, you might have to change the PHY's compatible string in the
> Device Tree to include its PHY OUI, e.g:
>
> compatible = "ethernet-phy-1234.5678" which will force the OF layer
> registering MDIO/PHY devices to probe to the specific driver that
> matches that PHY. Let us know if this does not work, in which case we
> might have to introduce another DT property that indicate a "double
> reset" is required.

If I understand what's going on correctly here, any instance of the VSC8541 phy 
has the unexpected feature where unmanaged mode is entered by following this 
particular reset sequence.  The specific wording from the datasheet is

    https://www.mouser.com/ds/2/523/Microsemi_VSC8541-01_Datasheet_10496_V40-1148034.pdf
    3.18.2 Unmanaged Applications
    To configure the device using unmanaged mode, perform the following steps:
    1. Apply power.
    2. Apply RefClk.
    3. Release reset, drive high. Power and clock must be high before releasing reset.
    Note: For unmanaged mode operation, the NRESET pin must have two rising 
          edges (logical 0-1-0-1 transition sequence) applied at this step.
    4. Wait 15 ms minimum.
    5. (Optional) For applications that gain register access to the device 
	using the management interface, steps 6–10 can then be performed in 
	order to modify default settings.

which is where the double reset sequence comes from.

For the HiFive Unleashed (a board with this phy) we perform this reset sequence 
in an early stage of the bootloader knows as the FSBL

    // VSC8541 PHY reset sequence; leave pull-down active for 2ms
    nsleep(2000000);
    // Set GPIO 12 (PHY NRESET) to OE=1 and OVAL=1
    atomic_fetch_or(&GPIO_REG(GPIO_OUTPUT_VAL), PHY_NRESET);
    atomic_fetch_or(&GPIO_REG(GPIO_OUTPUT_EN),  PHY_NRESET);
    nsleep(100);
    // Reset PHY again to enter unmanaged mode
    atomic_fetch_and(&GPIO_REG(GPIO_OUTPUT_VAL), ~PHY_NRESET);
    nsleep(100);
    atomic_fetch_or(&GPIO_REG(GPIO_OUTPUT_VAL), PHY_NRESET);
    nsleep(15000000);

which you can see here

    https://github.com/sifive/freedom-u540-c000-bootloader/blob/master/fsbl/main.c#L273

This is all fine as long as Linux doesn't go and reset the phy again. Until 
bafbdd527d56 ("phylib: Add device reset GPIO support") was the case.  After 
that commit I believe phylib is resetting the phy while attempting to enter 
unmanaged mode, which is now allowed in this particular chip.

Since it appears the phy is not usually described by the device tree but is 
instead discovered by probing a MII-based ID register, it seems the best place 
to put this is within the phy driver itself.  I find it's usually best to 
describe things with code, so I hacked up something like

    diff --git a/drivers/net/phy/mscc.c b/drivers/net/phy/mscc.c
    index 7cae17517744..8e0a71ee6bab 100644
    --- a/drivers/net/phy/mscc.c
    +++ b/drivers/net/phy/mscc.c
    @@ -1822,6 +1822,24 @@ static int vsc85xx_probe(struct phy_device *phydev)
     	return vsc85xx_dt_led_modes_get(phydev, default_mode);
     }
    
    +static int vsc8541_reset(struct phy_device *phydev, int value)
    +{
    +	WARN_ON(value != 0 || value != 1);
    +	mdio_device_reset(&phydev->mdio, value);
    +	if (value == 1) {
    +		/* The VSC8541 has an unexpected feature where a single reset
    +		 * rising edge can only be used to enter managed mode.  For
    +		 * unmanaged mode a pair of reset rising edges is necessary.
    +		 * */
    +		mdio_device_reset(&phydev_mdio, 0);
    +		mdio_device_reset(&phydev_mdio, 1);
    +
    +		/* After this pair of reset rising edges we must wait at least
    +		 * 15ms before writing any phy registers. */
    +		msleep(15);
    +	}
    +}
    +
     /* Microsemi VSC85xx PHYs */
     static struct phy_driver vsc85xx_driver[] = {
     {
    @@ -1927,6 +1945,7 @@ static struct phy_driver vsc85xx_driver[] = {
     	.get_sset_count = &vsc85xx_get_sset_count,
     	.get_strings    = &vsc85xx_get_strings,
     	.get_stats      = &vsc85xx_get_stats,
    +	.reset          = &vsc8541_reset,
     },
     {
     	.phy_id		= PHY_ID_VSC8574,
    diff --git a/include/linux/phy.h b/include/linux/phy.h
    index 3ea87f774a76..b8962ff409e8 100644
    --- a/include/linux/phy.h
    +++ b/include/linux/phy.h
    @@ -667,6 +667,10 @@ struct phy_driver {
     			    struct ethtool_tunable *tuna,
     			    const void *data);
     	int (*set_loopback)(struct phy_device *dev, bool enable);
    +
    +	/* An optional device-specific reset sequence */
    +	int (*reset)(struct phy_device *dev,
    +		     int value);
     };
     #define to_phy_driver(d) container_of(to_mdio_common_driver(d),		\
     				      struct phy_driver, mdiodrv)
    @@ -970,7 +974,10 @@ int phy_reset_after_clk_enable(struct phy_device *phydev);
    
     static inline void phy_device_reset(struct phy_device *phydev, int value)
     {
    -	mdio_device_reset(&phydev->mdio, value);
    +	if (phydev->reset)
    +		phydev->reset(phydev, value);
    +	else
    +		mdio_device_reset(&phydev->mdio, value);
     }
    
     #define phydev_err(_phydev, format, args...)	\

Note that I haven't even compiled this, and that msleep() is almost certainly 
garbage.

Am I missing something?

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macb: probe of 10090000.ethernet failed with error -110

[Andrew Lunn]

> This is all fine as long as Linux doesn't go and reset the phy again. Until
> bafbdd527d56 ("phylib: Add device reset GPIO support") was the case.  After
> that commit I believe phylib is resetting the phy while attempting to enter
> unmanaged mode, which is now allowed in this particular chip.
> 
> Since it appears the phy is not usually described by the device tree but is
> instead discovered by probing a MII-based ID register, it seems the best
> place to put this is within the phy driver itself.  I find it's usually best
> to describe things with code, so I hacked up something like

Talking to Florian, i was under the impression that you could not even
discover the device when its reset state what wrong. You could not
read the ID registers.

Your suggested change assumed you can discover the device. Is this
true?

	Thanks
		Andrew

Re: macb: probe of 10090000.ethernet failed with error -110

[Andrew Lunn]

> This is all fine as long as Linux doesn't go and reset the phy again. Until
> bafbdd527d56 ("phylib: Add device reset GPIO support") was the case.  After
> that commit I believe phylib is resetting the phy while attempting to enter
> unmanaged mode, which is now allowed in this particular chip.
> 
> Since it appears the phy is not usually described by the device tree but is
> instead discovered by probing a MII-based ID register, it seems the best
> place to put this is within the phy driver itself.  I find it's usually best
> to describe things with code, so I hacked up something like

Talking to Florian, i was under the impression that you could not even
discover the device when its reset state what wrong. You could not
read the ID registers.

Your suggested change assumed you can discover the device. Is this
true?

	Thanks
		Andrew

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macb: probe of 10090000.ethernet failed with error -110

[Palmer Dabbelt]

On Wed, 28 Nov 2018 18:28:58 PST (-0800), andrew at lunn.ch wrote:
>> This is all fine as long as Linux doesn't go and reset the phy again. Until
>> bafbdd527d56 ("phylib: Add device reset GPIO support") was the case.  After
>> that commit I believe phylib is resetting the phy while attempting to enter
>> unmanaged mode, which is now allowed in this particular chip.
>>
>> Since it appears the phy is not usually described by the device tree but is
>> instead discovered by probing a MII-based ID register, it seems the best
>> place to put this is within the phy driver itself.  I find it's usually best
>> to describe things with code, so I hacked up something like
>
> Talking to Florian, i was under the impression that you could not even
> discover the device when its reset state what wrong. You could not
> read the ID registers.
>
> Your suggested change assumed you can discover the device. Is this
> true?

Sorry, I can't tell that from reading the code.  Since our bootloader resets 
the phy into unmanaged mode I think that just deasserting reset should be OK, 
but I don't have much confidence in that -- once I run into one unexpected 
feature I start to expect more :)

It looks like there's already an expectation that at least the phy ID registers 
can be read between falling and rising edges of a reset, as that's how the 
fixups are handled.  Since the error message that shows up with a single 
(single as far as Linux is concerned, triple since a cold boot) reset rising 
edge still lists the phy by name I think that probing is working well enough, 
but I wouldn't be surprised if there's something in the middle that's gone 
wrong.  It's possible registering a fixup that does the double reset can get us 
through the probing sequence.

Maybe Atish or Paul can help out?  I'm a bit embarrassed to admit that I can't 
actually figure out how to boot the board any more, it's been a year since it's 
been my primary target and since I just to arch/riscv stuff now I rely them to 
test on the board...

Re: macb: probe of 10090000.ethernet failed with error -110

[Palmer Dabbelt]

On Wed, 28 Nov 2018 18:28:58 PST (-0800), andrew@lunn.ch wrote:
>> This is all fine as long as Linux doesn't go and reset the phy again. Until
>> bafbdd527d56 ("phylib: Add device reset GPIO support") was the case.  After
>> that commit I believe phylib is resetting the phy while attempting to enter
>> unmanaged mode, which is now allowed in this particular chip.
>>
>> Since it appears the phy is not usually described by the device tree but is
>> instead discovered by probing a MII-based ID register, it seems the best
>> place to put this is within the phy driver itself.  I find it's usually best
>> to describe things with code, so I hacked up something like
>
> Talking to Florian, i was under the impression that you could not even
> discover the device when its reset state what wrong. You could not
> read the ID registers.
>
> Your suggested change assumed you can discover the device. Is this
> true?

Sorry, I can't tell that from reading the code.  Since our bootloader resets 
the phy into unmanaged mode I think that just deasserting reset should be OK, 
but I don't have much confidence in that -- once I run into one unexpected 
feature I start to expect more :)

It looks like there's already an expectation that at least the phy ID registers 
can be read between falling and rising edges of a reset, as that's how the 
fixups are handled.  Since the error message that shows up with a single 
(single as far as Linux is concerned, triple since a cold boot) reset rising 
edge still lists the phy by name I think that probing is working well enough, 
but I wouldn't be surprised if there's something in the middle that's gone 
wrong.  It's possible registering a fixup that does the double reset can get us 
through the probing sequence.

Maybe Atish or Paul can help out?  I'm a bit embarrassed to admit that I can't 
actually figure out how to boot the board any more, it's been a year since it's 
been my primary target and since I just to arch/riscv stuff now I rely them to 
test on the board...

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macb: probe of 10090000.ethernet failed with error -110

[Andrew Lunn]

>    diff --git a/drivers/net/phy/mscc.c b/drivers/net/phy/mscc.c
>    index 7cae17517744..8e0a71ee6bab 100644
>    --- a/drivers/net/phy/mscc.c
>    +++ b/drivers/net/phy/mscc.c
>    @@ -1822,6 +1822,24 @@ static int vsc85xx_probe(struct phy_device *phydev)
>     	return vsc85xx_dt_led_modes_get(phydev, default_mode);
>     }
>    +static int vsc8541_reset(struct phy_device *phydev, int value)
>    +{
>    +	WARN_ON(value != 0 || value != 1);
>    +	mdio_device_reset(&phydev->mdio, value);
>    +	if (value == 1) {
>    +		/* The VSC8541 has an unexpected feature where a single reset
>    +		 * rising edge can only be used to enter managed mode.  For
>    +		 * unmanaged mode a pair of reset rising edges is necessary.
>    +		 * */
>    +		mdio_device_reset(&phydev_mdio, 0);
>    +		mdio_device_reset(&phydev_mdio, 1);
>    +
>    +		/* After this pair of reset rising edges we must wait at least
>    +		 * 15ms before writing any phy registers. */
>    +		msleep(15);
>    +	}
>    +}
>    +
>     /* Microsemi VSC85xx PHYs */
>     static struct phy_driver vsc85xx_driver[] = {
>     {
>    @@ -1927,6 +1945,7 @@ static struct phy_driver vsc85xx_driver[] = {
>     	.get_sset_count = &vsc85xx_get_sset_count,
>     	.get_strings    = &vsc85xx_get_strings,
>     	.get_stats      = &vsc85xx_get_stats,
>    +	.reset          = &vsc8541_reset,

So if we assume you can identify the PHY using its ID registers, you
can put this reset code into the soft_reset call. That gets called
first before anything else. There is no need to add a new function to
phy_driver.

	Andrew

Re: macb: probe of 10090000.ethernet failed with error -110

[Andrew Lunn]

>    diff --git a/drivers/net/phy/mscc.c b/drivers/net/phy/mscc.c
>    index 7cae17517744..8e0a71ee6bab 100644
>    --- a/drivers/net/phy/mscc.c
>    +++ b/drivers/net/phy/mscc.c
>    @@ -1822,6 +1822,24 @@ static int vsc85xx_probe(struct phy_device *phydev)
>     	return vsc85xx_dt_led_modes_get(phydev, default_mode);
>     }
>    +static int vsc8541_reset(struct phy_device *phydev, int value)
>    +{
>    +	WARN_ON(value != 0 || value != 1);
>    +	mdio_device_reset(&phydev->mdio, value);
>    +	if (value == 1) {
>    +		/* The VSC8541 has an unexpected feature where a single reset
>    +		 * rising edge can only be used to enter managed mode.  For
>    +		 * unmanaged mode a pair of reset rising edges is necessary.
>    +		 * */
>    +		mdio_device_reset(&phydev_mdio, 0);
>    +		mdio_device_reset(&phydev_mdio, 1);
>    +
>    +		/* After this pair of reset rising edges we must wait at least
>    +		 * 15ms before writing any phy registers. */
>    +		msleep(15);
>    +	}
>    +}
>    +
>     /* Microsemi VSC85xx PHYs */
>     static struct phy_driver vsc85xx_driver[] = {
>     {
>    @@ -1927,6 +1945,7 @@ static struct phy_driver vsc85xx_driver[] = {
>     	.get_sset_count = &vsc85xx_get_sset_count,
>     	.get_strings    = &vsc85xx_get_strings,
>     	.get_stats      = &vsc85xx_get_stats,
>    +	.reset          = &vsc8541_reset,

So if we assume you can identify the PHY using its ID registers, you
can put this reset code into the soft_reset call. That gets called
first before anything else. There is no need to add a new function to
phy_driver.

	Andrew

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Re: macb: probe of 10090000.ethernet failed with error -110

[Andreas Schwab]

On Nov 29 2018, Andrew Lunn <andrew@lunn.ch> wrote:

> So if we assume you can identify the PHY using its ID registers, you
> can put this reset code into the soft_reset call. That gets called
> first before anything else. There is no need to add a new function to
> phy_driver.

I've tried the following, but it made things only worse, with the
probing not working at all.

Andreas.

diff --git a/drivers/net/phy/mscc.c b/drivers/net/phy/mscc.c
index 7cae175177..65baf31331 100644
--- a/drivers/net/phy/mscc.c
+++ b/drivers/net/phy/mscc.c
@@ -1822,6 +1822,23 @@ static int vsc85xx_probe(struct phy_device *phydev)
 	return vsc85xx_dt_led_modes_get(phydev, default_mode);
 }
 
+static int vsc8541_soft_reset(struct phy_device *phydev)
+{
+	/* The VSC8541 has an unexpected feature where a single reset
+	 * rising edge can only be used to enter managed mode.  For
+	 * unmanaged mode a pair of reset rising edges is necessary.
+	 */
+	mdio_device_reset(&phydev->mdio, 0);
+	mdio_device_reset(&phydev->mdio, 1);
+
+	/* After this pair of reset rising edges we must wait at least
+	 * 15ms before writing any phy registers.
+	 */
+	msleep(15);
+
+	return genphy_soft_reset(phydev);
+}
+
 /* Microsemi VSC85xx PHYs */
 static struct phy_driver vsc85xx_driver[] = {
 {
@@ -1908,7 +1925,7 @@ static struct phy_driver vsc85xx_driver[] = {
 	.phy_id_mask    = 0xfffffff0,
 	.features	= PHY_GBIT_FEATURES,
 	.flags		= PHY_HAS_INTERRUPT,
-	.soft_reset	= &genphy_soft_reset,
+	.soft_reset	= &vsc8541_soft_reset,
 	.config_init    = &vsc85xx_config_init,
 	.config_aneg    = &vsc85xx_config_aneg,
 	.aneg_done	= &genphy_aneg_done,
-- 
2.19.2


-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

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