ACK/Cmnt: [OEM-B/OEM-OSP1-B/B/E/F/U][PATCH 1/1] UBUNTU SAUCE: r8151: check disconnect status after long sleep

[Kleber Souza]

On 24.02.20 07:58, You-Sheng Yang wrote:
> BugLink: https://bugs.launchpad.net/bugs/1864284
> 
> 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 at canonical.com>

This fix looks contained and simple enough to pull it in before it gets
accepted by upstream.

Note to the person applying this, to check the upstream discussion
thread for updates on the patch:

https://lore.kernel.org/linux-usb/20200224071541.117363-1-vicamo.yang@canonical.com/


Acked-by: Kleber Sacilotto de Souza <kleber.souza at 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);
>