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Subject: Re: [PATCH net-next v2 RESEND] net/usb/r8153_ecm: support ECM mode
 for RTL8153
To:     Hayes Wang <hayeswang@realtek.com>, netdev@vger.kernel.org
Cc:     nic_swsd@realtek.com, linux-kernel@vger.kernel.org,
        oliver@neukum.org, linux-usb@vger.kernel.org,
        'Linux Samsung SOC' <linux-samsung-soc@vger.kernel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Krzysztof Kozlowski <krzk@kernel.org>
From:   Marek Szyprowski <m.szyprowski@samsung.com>
Message-ID: <7fd014f2-c9a5-e7ec-f1c6-b3e4bb0f6eb6@samsung.com>
Date:   Fri, 13 Nov 2020 16:29:37 +0100
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References: <1394712342-15778-387-Taiwan-albertk@realtek.com>
        <1394712342-15778-392-Taiwan-albertk@realtek.com>
        <CGME20201113152938eucas1p2c8500d9d3d0c892c7c2a2d56b32fedc0@eucas1p2.samsung.com>
Precedence: bulk

Hi Hayes,

On 04.11.2020 03:19, Hayes Wang wrote:
> Support ECM mode based on cdc_ether with relative mii functions,
> when CONFIG_USB_RTL8152 is not set, or the device is not supported
> by r8152 driver.
>
> Both r8152 and r8153_ecm would check the return value of
> rtl8152_get_version() in porbe(). If rtl8152_get_version()
> return none zero value, the r8152 is used for the device
> with vendor mode. Otherwise, the r8153_ecm is used for the
> device with ECM mode.
>
> Signed-off-by: Hayes Wang <hayeswang@realtek.com>

This patch landed recently in linux-next and breaks ethernet operation 
on Samsung Exynos5422 Odroid XU4/HC1 boards when kernel is compiled from 
arm/configs/multi_v7_defconfig. The main problem is that the hardware is 
bound to r8153_ecm driver, not to the r8152. Manually switching the 
drivers by "echo 4-1:2.0 >/sys/bus/usb/drivers/r8153_ecm/unbind && echo 
4-1:2.0 >/sys/bus/usb/drivers/r8152/bind" fixes ethernet operation.

This is because in multi_v7_defconfig r8153_ecm driver is built-in (as 
it is tied to CONFIG_USB_NET_CDCETHER), while the r8152 driver is 
compiled as module and loaded when r8153_ecm has already bound.

I think that r8153_ecm driver should have a separate Kconfig symbol, 
which matches the r8152 driver (either both are built-in or both as 
modules), otherwise those 2 drivers cannot properly detect their cases.

> ---
>   drivers/net/usb/Makefile    |   2 +-
>   drivers/net/usb/r8152.c     |  30 +------
>   drivers/net/usb/r8153_ecm.c | 162 ++++++++++++++++++++++++++++++++++++
>   include/linux/usb/r8152.h   |  37 ++++++++
>   4 files changed, 204 insertions(+), 27 deletions(-)
>   create mode 100644 drivers/net/usb/r8153_ecm.c
>   create mode 100644 include/linux/usb/r8152.h
>
> > ...

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland