From: Heiner Kallweit <hkallweit1@gmail.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: Yonglong Liu <liuyonglong@huawei.com>,
davem@davemloft.net, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, linuxarm@huawei.com,
salil.mehta@huawei.com, yisen.zhuang@huawei.com,
shiju.jose@huawei.com
Subject: Re: [PATCH net] net: phy: rtl8211f: do a double read to get real time link status
Date: Thu, 8 Aug 2019 22:01:39 +0200 [thread overview]
Message-ID: <26e2c5c9-915c-858b-d091-e5bfa7ab6a5b@gmail.com> (raw)
In-Reply-To: <20190808194049.GM27917@lunn.ch>
On 08.08.2019 21:40, Andrew Lunn wrote:
>> @@ -568,6 +568,11 @@ int phy_start_aneg(struct phy_device *phydev)
>> if (err < 0)
>> goto out_unlock;
>>
>> + /* The PHY may not yet have cleared aneg-completed and link-up bit
>> + * w/o this delay when the following read is done.
>> + */
>> + usleep_range(1000, 2000);
>> +
>
> Hi Heiner
>
> Does 802.3 C22 say anything about this?
>
C22 says:
"The Auto-Negotiation process shall be restarted by setting bit 0.9 to a logic one. This bit is self-
clearing, and a PHY shall return a value of one in bit 0.9 until the Auto-Negotiation process has been
initiated."
Maybe we should read bit 0.9 in genphy_update_link() after having read BMSR and report
aneg-complete and link-up as false (no matter of their current value) if 0.9 is set.
> If this PHY is broken with respect to the standard, i would prefer the
> workaround is in the PHY specific driver code, not generic core code.
>
Based on the C22 statement above the PHY may not be broken and the typical time between
two MDIO accesses is sufficient for the PHY to clear the bits. I think of MDIO bus access
functions in network chips that have a 10us-20us delay after each MDIO access.
On HNS3 this may not be the case.
> Andrew
>
Heiner
next prev parent reply other threads:[~2019-08-08 20:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 13:16 [PATCH net] net: phy: rtl8211f: do a double read to get real time link status Yonglong Liu
2019-08-07 16:47 ` Heiner Kallweit
2019-08-08 1:15 ` Yonglong Liu
2019-08-08 6:11 ` Heiner Kallweit
2019-08-08 6:21 ` Yonglong Liu
2019-08-08 19:26 ` Heiner Kallweit
2019-08-08 19:40 ` Andrew Lunn
2019-08-08 20:01 ` Heiner Kallweit [this message]
2019-08-08 20:34 ` Andrew Lunn
2019-08-09 4:57 ` Yonglong Liu
2019-08-09 20:05 ` Heiner Kallweit
2019-08-12 4:49 ` Yonglong Liu
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