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Message-ID: <19eef958-5222-4663-bd94-5a5fb3d65caf@savoirfairelinux.com>
Date: Wed, 5 Jun 2024 10:33:35 +0200
From: Enguerrand de Ribaucourt <enguerrand.de-ribaucourt@...oirfairelinux.com>
To: Woojung.Huh@...rochip.com
Cc: andrew@...n.ch, hkallweit1@...il.com, linux@...linux.org.uk,
UNGLinuxDriver@...rochip.com, horms@...nel.org, Tristram.Ha@...rochip.com,
Arun.Ramadoss@...rochip.com, netdev@...r.kernel.org
Subject: Re: [PATCH net v5 1/4] net: phy: micrel: add Microchip KSZ 9897
Switch PHY support
Hello,
On 04/06/2024 22:49, Woojung.Huh@...rochip.com wrote:
> Hi Enguerrand,
>
> Can you help me to understand your setup? I could see you are using
> - Host CPU : i.MX6ULL
> - DSA Switch : KSZ9897R (https://www.microchip.com/en-us/product/ksz9897)
> - Host-to-KSZ interface : RGMII for data path & SPI for control
> Based on this, CPU port is either GMAC6 or GMAC7 (Figure 2-1 of [1])
>
> I have two questions for you.
> 1. PHY on CPU port
> Which GMAC (or port number) is connected between Host CPU and KSZ9897R?
> If CPU port is either GMAC6 or GMAC7, it is just a MAC-to-MAC connection over RGMII.
I'm using port number 6 as the CPU port for KSZ9897R. GMAC6 is directly
connected to the MAC of i.MX6ULL (driver is i.MX fec). I'm using RMII
since gigabit is not supported by the i.MX6ULL.
> 2. PHY ID
> Its PHY ID is different when checking datasheet of KSZ9897 and KSZ8081.
> PHY ID of Port 1-5 of KSZ9897 is 0x0022-0x1631 per [1]
> PHY ID of KSZ8081 is 0x0022-0x0156x per [2]
That's true for port 1-5, however, I found out that the phy_id emitted
by GMAC6 is 0x00221561. It is the same as KSZ8081-revA3 according to the
datasheet. I also studied all registers at runtime for a reliable
difference to implement something like ksz8051_ksz8795_match_phy_device
between GMAC6 and KSZ8081, but none appeared to me. Following
suggestions by Andrew Lunn, I added this virtual phy_id (0x002217ff) to
hardcode in the devicetree. I'm happy with this solution.
>
> Beside patch, you can create a ticket to Microchip site (https://microchipsupport.force.com/s/supportservice)
> if you think it is easier to solve your problem.
I created a joined ticket for tracking (Case number 01457279).
>
Thank you very much for your time,
Enguerrand de Ribaucourt
> Best regards,
> Woojung
>
> [1] https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ProductDocuments/DataSheets/KSZ9897R-Data-Sheet-DS00002330D.pdf
> [2] https://www.microchip.com/en-us/product/ksz8081#document-table
>
>> -----Original Message-----
>> From: Enguerrand de Ribaucourt <enguerrand.de-
>> ribaucourt@...oirfairelinux.com>
>> Sent: Tuesday, June 4, 2024 5:23 AM
>> To: netdev@...r.kernel.org
>> Cc: andrew@...n.ch; hkallweit1@...il.com; linux@...linux.org.uk; Woojung Huh
>> - C21699 <Woojung.Huh@...rochip.com>; UNGLinuxDriver
>> <UNGLinuxDriver@...rochip.com>; horms@...nel.org; Tristram Ha - C24268
>> <Tristram.Ha@...rochip.com>; Arun Ramadoss - I17769
>> <Arun.Ramadoss@...rochip.com>; Enguerrand de Ribaucourt <enguerrand.de-
>> ribaucourt@...oirfairelinux.com>
>> Subject: [PATCH net v5 1/4] net: phy: micrel: add Microchip KSZ 9897 Switch
>> PHY support
>>
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the
>> content is safe
>>
>> There is a DSA driver for microchip,ksz9897 which can be controlled
>> through SPI or I2C. This patch adds support for it's CPU ports PHYs to
>> also allow network access to the switch's CPU port.
>>
>> The CPU ports PHYs of the KSZ9897 are not documented in the datasheet.
>> They weirdly use the same PHY ID as the KSZ8081, which is a different
>> PHY and that driver isn't compatible with KSZ9897. Before this patch,
>> the KSZ8081 driver was used for the CPU ports of the KSZ9897 but the
>> link would never come up.
>>
>> A new driver for the KSZ9897 is added, based on the compatible KSZ87XX.
>> I could not test if Gigabit Ethernet works, but the link comes up and
>> can successfully allow packets to be sent and received with DSA tags.
>>
>> To resolve the KSZ8081/KSZ9897 phy_id conflicts, I could not find any
>> stable register to distinguish them. Instead of a match_phy_device() ,
>> I've declared a virtual phy_id with the highest value in Microchip's OUI
>> range.
>>
>> Example usage in the device tree:
>> compatible = "ethernet-phy-id0022.17ff";
>>
>> A discussion to find better alternatives had been opened with the
>> Microchip team, with no response yet.
>>
>> See https://lore.kernel.org/all/20220207174532.362781-1-enguerrand.de-
>> ribaucourt@...oirfairelinux.com/
>>
>> Fixes: b987e98e50ab ("dsa: add DSA switch driver for Microchip KSZ9477")
>> Signed-off-by: Enguerrand de Ribaucourt <enguerrand.de-
>> ribaucourt@...oirfairelinux.com>
>> ---
>> v5:
>> - rewrap comments
>> - restore suspend/resume for KSZ9897
>> v4: https://lore.kernel.org/all/20240531142430.678198-2-enguerrand.de-
>> ribaucourt@...oirfairelinux.com/
>> - rebase on net/main
>> - add Fixes tag
>> - use pseudo phy_id instead of of_tree search
>> v3: https://lore.kernel.org/all/20240530102436.226189-2-enguerrand.de-
>> ribaucourt@...oirfairelinux.com/
>> ---
>> drivers/net/phy/micrel.c | 13 ++++++++++++-
>> include/linux/micrel_phy.h | 4 ++++
>> 2 files changed, 16 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
>> index 8c20cf937530..11e58fc628df 100644
>> --- a/drivers/net/phy/micrel.c
>> +++ b/drivers/net/phy/micrel.c
>> @@ -16,7 +16,7 @@
>> * ksz8081, ksz8091,
>> * ksz8061,
>> * Switch : ksz8873, ksz886x
>> - * ksz9477, lan8804
>> + * ksz9477, ksz9897, lan8804
>> */
>>
>> #include <linux/bitfield.h>
>> @@ -5545,6 +5545,16 @@ static struct phy_driver ksphy_driver[] = {
>> .suspend = genphy_suspend,
>> .resume = ksz9477_resume,
>> .get_features = ksz9477_get_features,
>> +}, {
>> + .phy_id = PHY_ID_KSZ9897,
>> + .phy_id_mask = MICREL_PHY_ID_MASK,
>> + .name = "Microchip KSZ9897 Switch",
>> + /* PHY_BASIC_FEATURES */
>> + .config_init = kszphy_config_init,
>> + .config_aneg = ksz8873mll_config_aneg,
>> + .read_status = ksz8873mll_read_status,
>> + .suspend = genphy_suspend,
>> + .resume = genphy_resume,
>> } };
>>
>> module_phy_driver(ksphy_driver);
>> @@ -5570,6 +5580,7 @@ static struct mdio_device_id __maybe_unused
>> micrel_tbl[] = {
>> { PHY_ID_LAN8814, MICREL_PHY_ID_MASK },
>> { PHY_ID_LAN8804, MICREL_PHY_ID_MASK },
>> { PHY_ID_LAN8841, MICREL_PHY_ID_MASK },
>> + { PHY_ID_KSZ9897, MICREL_PHY_ID_MASK },
>> { }
>> };
>>
>> diff --git a/include/linux/micrel_phy.h b/include/linux/micrel_phy.h
>> index 591bf5b5e8dc..81cc16dc2ddf 100644
>> --- a/include/linux/micrel_phy.h
>> +++ b/include/linux/micrel_phy.h
>> @@ -39,6 +39,10 @@
>> #define PHY_ID_KSZ87XX 0x00221550
>>
>> #define PHY_ID_KSZ9477 0x00221631
>> +/* Pseudo ID to specify in compatible field of device tree.
>> + * Otherwise the device reports the same ID as KSZ8081 on CPU ports.
>> + */
>> +#define PHY_ID_KSZ9897 0x002217ff
>>
>> /* struct phy_device dev_flags definitions */
>> #define MICREL_PHY_50MHZ_CLK BIT(0)
>> --
>> 2.34.1
>
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