netdev - Re: [PATCH net 2/3] net: phy: micrel: Remove latency from driver

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Message-ID: <20220401135918.4tvwe6cfyku6l5wf@lx-anielsen>
Date:   Fri, 1 Apr 2022 15:59:18 +0200
From:   "Allan W. Nielsen" <allan.nielsen@...rochip.com>
To:     Horatiu Vultur <horatiu.vultur@...rochip.com>
CC:     Andrew Lunn <andrew@...n.ch>, <netdev@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <hkallweit1@...il.com>, <linux@...linux.org.uk>,
        <Divya.Koppera@...rochip.com>, <davem@...emloft.net>,
        <kuba@...nel.org>, <richardcochran@...il.com>,
        <UNGLinuxDriver@...rochip.com>
Subject: Re: [PATCH net 2/3] net: phy: micrel: Remove latency from driver

On 01.04.2022 15:34, Horatiu Vultur wrote:
>The 04/01/2022 14:47, Andrew Lunn wrote:
>>
>> On Fri, Apr 01, 2022 at 11:48:04AM +0200, Horatiu Vultur wrote:
>> > Based on the discussions here[1], the PHY driver is the wrong place
>> > to set the latencies, therefore remove them.
>> >
>> > [1] https://lkml.org/lkml/2022/3/4/325
>> >
>> > Fixes: ece19502834d84 ("net: phy: micrel: 1588 support for LAN8814 phy")
>> > Signed-off-by: Horatiu Vultur <horatiu.vultur@...rochip.com>
>>
>> Thanks for the revert.
>>
>> Reviewed-by: Andrew Lunn <andrew@...n.ch>
>>
>> > -static struct kszphy_latencies lan8814_latencies = {
>> > -     .rx_10          = 0x22AA,
>> > -     .tx_10          = 0x2E4A,
>> > -     .rx_100         = 0x092A,
>> > -     .tx_100         = 0x02C1,
>> > -     .rx_1000        = 0x01AD,
>> > -     .tx_1000        = 0x00C9,
>> > -};
>>
>> What are the reset defaults of these?
>
>Those are actually the reset values.
>
>> I'm just wondering if we should
>> explicitly set them to 0, so we don't get into a mess where some
>> vendor bootloader sets values but mainline bootloader does not,
>> breaking a configuration where the userspace daemon does the correct?
>
>It would be fine for me to set them to 0. But then definitely we need a
>way to set these latencies from userspace.
I would like to keep the default values. With default values, you can
get PTP working (accuracy is not great - but it is much better than
if set to zero).

There is no risk of bootloaders to pre-load other values, as the kernel
will reset the PHY, and after reset we will be back to these numbers.

/Allan