netdev - Re: DP83867 ethernet PHY regression

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Date: Thu, 25 May 2023 03:18:34 -0500
From: "Bajjuri, Praneeth" <praneeth@...com>
To: Francesco Dolcini <francesco@...cini.it>,
        Johannes Pointner
	<h4nn35.work@...il.com>,
        Siddharth Vadapalli <s-vadapalli@...com>, <vikram.sharma@...com>
CC: Bagas Sanjaya <bagasdotme@...il.com>, Andrew Lunn <andrew@...n.ch>,
        Heiner
 Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Eric
 Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni
	<pabeni@...hat.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: DP83867 ethernet PHY regression

Andrew,Francesco,

On 5/25/2023 2:33 AM, Francesco Dolcini wrote:
> Hello Johannes,
> 
> On Thu, May 25, 2023 at 08:31:00AM +0200, Johannes Pointner wrote:
>> On Wed, May 24, 2023 at 3:22 PM Bagas Sanjaya <bagasdotme@...il.com> wrote:
>>>
>>> On Mon, May 22, 2023 at 04:58:46PM +0200, Francesco Dolcini wrote:
>>>> Hello all,
>>>> commit da9ef50f545f ("net: phy: dp83867: perform soft reset and retain
>>>> established link") introduces a regression on my TI AM62 based board.
>>>>
>>>> I have a working DTS with Linux TI 5.10 downstream kernel branch, while
>>>> testing the DTS with v6.4-rc in preparation of sending it to the mailing
>>>> list I noticed that ethernet is working only on a cold poweron.
>>>>
>>>> With da9ef50f545f reverted it always works.

Thank you for bringing this issue to attention.
I have looped Siddharth and vikram to further investigate and provide input.


>>>>
>>>> Here the DTS snippet for reference:
>>>>
>>>> &cpsw_port1 {
>>>>        phy-handle = <&cpsw3g_phy0>;
>>>>        phy-mode = "rgmii-rxid";
>>>> };
>>>>
>>>> &cpsw3g_mdio {
>>>>        assigned-clocks = <&k3_clks 157 20>;
>>>>        assigned-clock-parents = <&k3_clks 157 22>;
>>>>        assigned-clock-rates = <25000000>;
>>>>
>>>>        cpsw3g_phy0: ethernet-phy@0 {
>>>>                compatible = "ethernet-phy-id2000.a231";
>>>>                reg = <0>;
>>>>                interrupt-parent = <&main_gpio0>;
>>>>                interrupts = <25 IRQ_TYPE_EDGE_FALLING>;
>>>>                reset-gpios = <&main_gpio0 17 GPIO_ACTIVE_LOW>;
>>>>                reset-assert-us = <10>;
>>>>                reset-deassert-us = <1000>;
>>>>                ti,fifo-depth = <DP83867_PHYCR_FIFO_DEPTH_4_B_NIB>;
>>>>                ti,rx-internal-delay = <DP83867_RGMIIDCTL_2_00_NS>;
>>>>        };
>>>> };
>>>>
>>>
>>> Thanks for the regression report. I'm adding it to regzbot:
>>>
>>> #regzbot ^introduced: da9ef50f545f86
>>> #regzbot title: TI AM62 DTS regression due to dp83867 soft reset
>>
>> Hello Francesco,
>>
>> I had a similar issue with a patch like this, but in my case it was the DP83822.
>> https://lore.kernel.org/netdev/CAHvQdo2yzJC89K74c_CZFjPydDQ5i22w36XPR5tKVv_W8a2vcg@mail.gmail.com/
>> I also raised the question for the commit da9ef50f545f.
>> https://lore.kernel.org/lkml/CAHvQdo1U_L=pETmTJXjdzO+k7vNTxMyujn99Y3Ot9xAyQu=atQ@mail.gmail.com/
>>
>> The problem was/is for me that the phy gets the clock from the CPU and
>> the phy is already initialized in the u-boot.
>> During the Linux kernel boot up there is a short amount of time where
>> no clock is delivered to the phy.
>> The phy didn't like this and was most of the time not usable anymore.
>> The only thing that brought the phy/link back was resetting the phy
>> using the phytool.
> 
> I had a look and it seems that is a different issue here, but I cannot
> exclude that this is related.
> 
> First the link up/down, negotiation and mdio and related communication
> is perfectly fine, what it looks like is not working is that no data is
> flowing over RGMII.
> 
> Second, also in our case the clock is coming from the SoC, however this
> clock is enabled way earlier in the boot, and at that time the phy is
> even in reset.
> 
>   phy reset asserted
>   . SPL on TI AM62 R5
>     . enable clock
>   . SPL on TI AM62 A
>   . U-Boot proper on TI AM62 A
>     .release phy reset
> 
> The phy reset is also configured in the DTS and used by the Linux driver.
> 
> In addition to that, as I already clarified in my second email, the
> issue is happening also on a cold poweron. It happens most of the time,
> but not always.
> 
> Francesco
> 
>