Re: Regression in v4.20 with net phy soft reset changes

On Thursday 10 January 2019 10:36 AM, Keerthy wrote:

On Thursday 10 January 2019 03:06 AM, Tony Lindgren wrote:

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Hi,

* Heiner Kallweit [off-list ref] [190109 19:28]:

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On 09.01.2019 20:06, Tony Lindgren wrote:

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Commit 6e2d85ec0559 ("net: phy: Stop with excessive soft reset") caused
a regression where suspend resume cycle fails to bring up Ethernet on at
least cpsw on am437x-sk-evm.

What kind of PHY and which PHY driver is used with this board?
I found one schematics of am437x where a KSZ9031RN PHY is used.
Is it the same on your board?

Yes that's the phy.

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As described in the commit message of this commit you would have
the option to implement the soft_reset callback in the PHY driver.
Can you try to add .soft_reset = genphy_soft_reset to the
KSZ9031 driver config in drivers/net/phy/micrel.c and check whether
it fixes the issue?

Yes that seems to work based on a quick test of five suspend
resume cycles.

Removing Grygorii as the e-mail no longer exists

To add to Tony's observations. I ran a 100 time suspend/resume adding the
soft_reset hook to the phy_driver structs in drivers/net/phy/micrel.c and
suspend/resume (DS0) works nicely.

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I wonder what all hardware this issue affects though?

It's probably best that the network folks check what all
hardare needs patching.

For TI hardware, Sekhar and TI network folks, can you guys
please check the various TI SoCs for multiple suspend resume
cycles with v5.0-rc1 and patch accordingly? See also below
for something else to check, 10 seconds to resume a phy
seems very long to me :)

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Keerthy noticed this may not happen on the first resume, but usually
happens after few suspend resume cycles. The most working suspend resume
cycles I've seen with the commit above is three.

...

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Note that unrelated to the commit above, there may be other issues too
as the cpsw phy LED seems to come on only after about five seconds with
about total of 10 seconds before the Ethernet is up again.

Regards,

Tony

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