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Message-ID: <42abfa5c-1e84-63c7-1f3d-4816d232dc98@gmail.com>
Date: Sat, 12 Oct 2019 23:22:09 +0200
From: Heiner Kallweit <hkallweit1@...il.com>
To: Marek Vasut <marex@...x.de>, netdev@...r.kernel.org
Cc: Andrew Lunn <andrew@...n.ch>,
"David S . Miller" <davem@...emloft.net>,
Florian Fainelli <f.fainelli@...il.com>,
George McCollister <george.mccollister@...il.com>,
Tristram Ha <Tristram.Ha@...rochip.com>,
Woojung Huh <woojung.huh@...rochip.com>
Subject: Re: [PATCH V2 1/2] net: phy: micrel: Discern KSZ8051 and KSZ8795 PHYs
On 12.10.2019 22:58, Heiner Kallweit wrote:
> On 10.10.2019 21:46, Marek Vasut wrote:
>> The KSZ8051 PHY and the KSZ8794/KSZ8795/KSZ8765 switch share exactly the
>> same PHY ID. Since KSZ8051 is higher in the ksphy_driver[] list of PHYs
>> in the micrel PHY driver, it is used even with the KSZ87xx switch. This
>> is wrong, since the KSZ8051 configures registers of the PHY which are
>> not present on the simplified KSZ87xx switch PHYs and misconfigures
>> other registers of the KSZ87xx switch PHYs.
>>
>> Fortunatelly, it is possible to tell apart the KSZ8051 PHY from the
>> KSZ87xx switch by checking the Basic Status register Bit 0, which is
>> read-only and indicates presence of the Extended Capability Registers.
>> The KSZ8051 PHY has those registers while the KSZ87xx switch does not.
>>
>> This patch implements simple check for the presence of this bit for
>> both the KSZ8051 PHY and KSZ87xx switch, to let both use the correct
>> PHY driver instance.
>>
>> Signed-off-by: Marek Vasut <marex@...x.de>
>> Cc: Andrew Lunn <andrew@...n.ch>
>> Cc: David S. Miller <davem@...emloft.net>
>> Cc: Florian Fainelli <f.fainelli@...il.com>
>> Cc: George McCollister <george.mccollister@...il.com>
>> Cc: Heiner Kallweit <hkallweit1@...il.com>
>> Cc: Tristram Ha <Tristram.Ha@...rochip.com>
>> Cc: Woojung Huh <woojung.huh@...rochip.com>
>> ---
>> NOTE: It was also suggested to populate phydev->dev_flags to discern
>> the PHY from the switch, this does not work for setups where
>> the switch is used as a PHY without a DSA driver. Checking the
>> BMSR Bit 0 for Extended Capability Register works for both DSA
>> and non-DSA usecase.
>> V2: Move phy_id check into ksz8051_match_phy_device() and
>> ksz8795_match_phy_device() and drop phy_id{,_mask} from the
>> ksphy_driver[] list to avoid matching on other PHY IDs.
>> ---
>> drivers/net/phy/micrel.c | 40 ++++++++++++++++++++++++++++++++++++----
>> 1 file changed, 36 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
>> index 2fea5541c35a..028a4a177790 100644
>> --- a/drivers/net/phy/micrel.c
>> +++ b/drivers/net/phy/micrel.c
>> @@ -341,6 +341,25 @@ static int ksz8041_config_aneg(struct phy_device *phydev)
>> return genphy_config_aneg(phydev);
>> }
>>
>> +static int ksz8051_match_phy_device(struct phy_device *phydev)
>> +{
>> + int ret;
>> +
>> + if ((phydev->phy_id & MICREL_PHY_ID_MASK) != PHY_ID_KSZ8051)
>> + return 0;
>> +
>> + ret = phy_read(phydev, MII_BMSR);
>> + if (ret < 0)
>> + return ret;
>> +
>> + /* KSZ8051 PHY and KSZ8794/KSZ8795/KSZ8765 switch share the same
>> + * exact PHY ID. However, they can be told apart by the extended
>> + * capability registers presence. The KSZ8051 PHY has them while
>> + * the switch does not.
>> + */
>> + return ret & BMSR_ERCAP;
>> +}
>> +
>> static int ksz8081_config_init(struct phy_device *phydev)
>> {
>> /* KSZPHY_OMSO_FACTORY_TEST is set at de-assertion of the reset line
>> @@ -364,6 +383,21 @@ static int ksz8061_config_init(struct phy_device *phydev)
>> return kszphy_config_init(phydev);
>> }
>>
>> +static int ksz8795_match_phy_device(struct phy_device *phydev)
>> +{
>> + int ret;
>> +
>> + if ((phydev->phy_id & MICREL_PHY_ID_MASK) != PHY_ID_KSZ8795)
>> + return 0;
>> +
>> + ret = phy_read(phydev, MII_BMSR);
>> + if (ret < 0)
>> + return ret;
>> +
>> + /* See comment in ksz8051_match_phy_device() for details. */
>> + return !(ret & BMSR_ERCAP);
>> +}
>> +
>> static int ksz9021_load_values_from_of(struct phy_device *phydev,
>> const struct device_node *of_node,
>> u16 reg,
>> @@ -1017,8 +1051,6 @@ static struct phy_driver ksphy_driver[] = {
>> .suspend = genphy_suspend,
>> .resume = genphy_resume,
>> }, {
>> - .phy_id = PHY_ID_KSZ8051,
>> - .phy_id_mask = MICREL_PHY_ID_MASK,
>> .name = "Micrel KSZ8051",
>> /* PHY_BASIC_FEATURES */
>> .driver_data = &ksz8051_type,
>> @@ -1029,6 +1061,7 @@ static struct phy_driver ksphy_driver[] = {
>> .get_sset_count = kszphy_get_sset_count,
>> .get_strings = kszphy_get_strings,
>> .get_stats = kszphy_get_stats,
>> + .match_phy_device = ksz8051_match_phy_device,
>> .suspend = genphy_suspend,
>> .resume = genphy_resume,
>> }, {
>> @@ -1141,13 +1174,12 @@ static struct phy_driver ksphy_driver[] = {
>> .suspend = genphy_suspend,
>> .resume = genphy_resume,
>> }, {
>> - .phy_id = PHY_ID_KSZ8795,
>> - .phy_id_mask = MICREL_PHY_ID_MASK,
>> .name = "Micrel KSZ8795",
>> /* PHY_BASIC_FEATURES */
>> .config_init = kszphy_config_init,
>> .config_aneg = ksz8873mll_config_aneg,
>> .read_status = ksz8873mll_read_status,
>> + .match_phy_device = ksz8795_match_phy_device,
>> .suspend = genphy_suspend,
>> .resume = genphy_resume,
>> }, {
>>
>
> Patch needs to be annotated as "net-next".
> See https://www.kernel.org/doc/Documentation/networking/netdev-FAQ.txt
>
Except you consider this a fix, then it would require a Fixes tag and
should be annotated "net". The question is:
Do KSZ87xx switches misbehave currently?
> Apart from that:
> Reviewed-by: Heiner Kallweit <hkallweit1@...il.com>
>
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