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SubjectRE: [PATCH v1 0/3] fix macb phy probe failure if phy-reset is not handled
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Hello,

A gentle reminder. Any suggestions here?

BR,
Sagar

> -----Original Message-----
> From: Sagar Kadam <sagar.kadam@sifive.com>
> Sent: Wednesday, May 13, 2020 7:27 PM
> To: linux-kernel@vger.kernel.org; linux-riscv@lists.infradead.org;
> devicetree@vger.kernel.org; robh+dt@kernel.org
> Cc: palmer@dabbelt.com; Paul Walmsley <paul.walmsley@sifive.com>;
> atish.patra@wdc.com; Sagar Kadam <sagar.kadam@sifive.com>
> Subject: [PATCH v1 0/3] fix macb phy probe failure if phy-reset is not
> handled
>
> HiFive Unleashed is having VSC8541-01 ethernet phy device and requires a
> specific reset sequence of 0-1-0-1 in order to use it in unmanaged mode.
> This series addresses a corner case where phy reset is not handled by boot
> stages prior to linux.
> Somewhat similar unreliable phy probe failure was reported and discussed
> here [1].
> The macb driver fails to detect the ethernet phy device if the bootloader
> doesn't provide a proper reset sequence to the phy device or the phy itself
> is in some invalid state. Currently, the FSBL is resetting the phy device, and
> so there is no issue observed in the linux network setup.
>
> The series is based on linux-5.7-rc5.
> Patch 1: Add the OUI to the phy dt node to fix issue of missing mdio device
> Patch 2 and 3:
> Resetting phy needs GPIO support so add to dt and defconfig.
>
> [1] https://lkml.org/lkml/2018/11/29/154
>
> To reproduce the issue:
> 1. Comment out VSC8541 reset sequence in fsbl/main.c
> from within the freedom-u540-c000-bootloader.
> 2. Build and flash fsbl.bin to micro sdcard.
>
> Boot the board and bootlog will show network setup failure messages as:
>
> [ 1.069474] libphy: MACB_mii_bus: probed [ 1.073092] mdio_bus
> 10090000.ethernet-ffffffff: MDIO device at address 0
> is missing
> .....
> [ 1.979252] macb 10090000.ethernet eth0: Could not attach PHY (-19)
>
> 3. Now apply the series build, and boot kernel.
> 4. MACB and VSC8541 driver get successfully probed and the network is set
> without any failure.
>
>
> So irrespective of whether the prior stages handle the phy reset sequence,
> the probing is successful in both the cases of cold boot and warm boot.
>
> Change History:
> ===============================
> V1:
> -Ignore 4th patch as suggested and so removed it from the series.
> -Verified this series on 5.7-rc5.
>
> V0: Base RFC patch. Verified on 5.7-rc2
>
>
> Sagar Shrikant Kadam (3):
> dts: phy: fix missing mdio device and probe failure of vsc8541-01
> device
> dts: phy: add GPIO number and active state used for phy reset
> riscv: defconfig: enable gpio support for HiFive Unleashed
>
> arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts | 2 ++
> arch/riscv/configs/defconfig | 2 ++
> 2 files changed, 4 insertions(+)
>
> --
> 2.7.4

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