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SubjectRe: r8151: check disconnect status after long sleep
nit: The commit message title tag should be "r8152", instead of "r8151".

On Mon, Feb 24, 2020 at 03:15:41PM +0800, You-Sheng Yang wrote:
> Dell USB Type C docking WD19/WD19DC attaches additional peripherals as:
>
> /: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/6p, 5000M
> |__ Port 1: Dev 11, If 0, Class=Hub, Driver=hub/4p, 5000M
> |__ Port 3: Dev 12, If 0, Class=Hub, Driver=hub/4p, 5000M
> |__ Port 4: Dev 13, If 0, Class=Vendor Specific Class,
> Driver=r8152, 5000M
>
> where usb 2-1-3 is a hub connecting all USB Type-A/C ports on the dock.
>
> When hotplugging such dock with additional usb devices already attached on
> it, the probing process may reset usb 2.1 port, therefore r8152 ethernet
> device is also reset. However, during r8152 device init there are several
> for-loops that, when it's unable to retrieve hardware registers due to
> being discconected from USB, may take up to 14 seconds each in practice,
> and that has to be completed before USB may re-enumerate devices on the
> bus. As a result, devices attached to the dock will only be available
> after nearly 1 minute after the dock was plugged in:
>
> [ 216.388290] [250] r8152 2-1.4:1.0: usb_probe_interface
> [ 216.388292] [250] r8152 2-1.4:1.0: usb_probe_interface - got id
> [ 258.830410] r8152 2-1.4:1.0 (unnamed net_device) (uninitialized): PHY not ready
> [ 258.830460] r8152 2-1.4:1.0 (unnamed net_device) (uninitialized): Invalid header when reading pass-thru MAC addr
> [ 258.830464] r8152 2-1.4:1.0 (unnamed net_device) (uninitialized): Get ether addr fail
>
> This can be reproduced on all kernel versions up to latest v5.6-rc2, but
> after v5.5-rc7 the reproduce rate is dramatically lower to 1/30 or so
> while it was around 1/2.
>
> The time consuming for-loops are at:
> https://elixir.bootlin.com/linux/v5.5/source/drivers/net/usb/r8152.c#L3206
> https://elixir.bootlin.com/linux/v5.5/source/drivers/net/usb/r8152.c#L5400
> https://elixir.bootlin.com/linux/v5.5/source/drivers/net/usb/r8152.c#L5537
>
> Signed-off-by: You-Sheng Yang <vicamo.yang@canonical.com>
> ---
> drivers/net/usb/r8152.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
> index 78ddbaf6401b..95b19ce96513 100644
> --- a/drivers/net/usb/r8152.c
> +++ b/drivers/net/usb/r8152.c
> @@ -3221,6 +3221,8 @@ static u16 r8153_phy_status(struct r8152 *tp, u16 desired)
> }
>
> msleep(20);
> + if (test_bit(RTL8152_UNPLUG, &tp->flags))
> + break;
> }
>
> return data;
> @@ -5402,7 +5404,10 @@ static void r8153_init(struct r8152 *tp)
> if (ocp_read_word(tp, MCU_TYPE_PLA, PLA_BOOT_CTRL) &
> AUTOLOAD_DONE)
> break;
> +
> msleep(20);
> + if (test_bit(RTL8152_UNPLUG, &tp->flags))
> + break;
> }
>
> data = r8153_phy_status(tp, 0);
> @@ -5539,7 +5544,10 @@ static void r8153b_init(struct r8152 *tp)
> if (ocp_read_word(tp, MCU_TYPE_PLA, PLA_BOOT_CTRL) &
> AUTOLOAD_DONE)
> break;
> +
> msleep(20);
> + if (test_bit(RTL8152_UNPLUG, &tp->flags))
> + break;
> }
>
> data = r8153_phy_status(tp, 0);
> --
> 2.25.0
>

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