Re: [PATCH 3/4] thunderbolt: Fix adapter init handling during switch add

Sanjay R Mehta
2021-08-03T12:29:23Z

On 8/3/2021 2:35 PM, Mika Westerberg wrote:
> [CAUTION: External Email]
>
> Hi,
>
> On Tue, Aug 03, 2021 at 12:23:44AM +0530, Sanjay R Mehta wrote:
>>
>>
>> On 8/2/2021 8:56 PM, Mika Westerberg wrote:
>>> [CAUTION: External Email]
>>>
>>> On Mon, Aug 02, 2021 at 07:58:19AM -0500, Sanjay R Mehta wrote:
>>>> From: Sanjay R Mehta <sanju.mehta@amd.com>
>>>>
>>>> Adapter0 (Port0) is the control adapter on the AMD USB4 host router.
>>>> As per USB4 spec in "Section 1.8", Control Adapters do not
>>>> have an Adapter Configuration Space".
>>>>
>>>> The read requests on Adapter0 time's out and driver initialization fails.
>>>>
>>>> Hence Disabling the Adapter in case of read-request timeout and continuing
>>>> the driver init.
>>>>
>>>> Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
>>>> Signed-off-by: Sanjay R Mehta <sanju.mehta@amd.com>
>>>> ---
>>>> drivers/thunderbolt/switch.c | 3 ++-
>>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
>>>> index 83b1ef3..effbfe4 100644
>>>> --- a/drivers/thunderbolt/switch.c
>>>> +++ b/drivers/thunderbolt/switch.c
>>>> @@ -2747,8 +2747,9 @@ int tb_switch_add(struct tb_switch *sw)
>>>> }
>>>> ret = tb_init_port(&sw->ports[i]);
>>>> if (ret) {
>>>> + sw->ports[i].disabled = true;
>>>> dev_err(&sw->dev, "failed to initialize port %d\n", i);
>>>> - return ret;
>>>> + continue;
>>>
>>> Instead of this, would it work if we start the loop at 1? In case of the
>>> control adapter (0) tb_port_init() does not do anything useful anyway
>>> and it actually would simplify that function too if we get rid of the
>>> special casing.
>>>
>> Hi Mika,
>>
>> If we start loop from 1, it will work for host router
>> but this will skip port (0) on device router which may be valid port.
>
> For device router adapter 0 is also contror adapter so I think we can
> just skip it here unconditionally.

Sure Mika. Will send the updated changes.

Thanks,
Sanjay

>