Re: [PATCH 2/4] usb: typec: tcpm: fix multiple times discover svids error

Frank Wang
2023-03-15T02:57:46Z

Hi Heikki,

On 2023/3/14 17:22, Heikki Krogerus wrote:
> On Mon, Mar 13, 2023 at 10:58:41AM +0800, Frank Wang wrote:
>> PD3.0 Spec 6.4.4.3.2 say that only Responder supports 12 or more SVIDs,
>> the Discover SVIDs Command Shall be executed multiple times until a
>> Discover SVIDs VDO is returned ending either with a SVID value of
>> 0x0000 in the last part of the last VDO or with a VDO containing two
>> SVIDs with values of 0x0000.
>>
>> In the current implementation, if the last VDO does not find that the
>> Discover SVIDs Command would be executed multiple times even if the
>> Responder SVIDs are less than 12, and we found some odd dockers just
>> meet this case. So fix it.
>>
>> Signed-off-by: Frank Wang <frank.wang@rock-chips.com>
>> ---
>> drivers/usb/typec/tcpm/tcpm.c | 16 +++++++++++++++-
>> 1 file changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
>> index 66de02a56f512..2962f7c261976 100644
>> --- a/drivers/usb/typec/tcpm/tcpm.c
>> +++ b/drivers/usb/typec/tcpm/tcpm.c
>> @@ -1515,7 +1515,21 @@ static bool svdm_consume_svids(struct tcpm_port *port, const u32 *p, int cnt)
>> pmdata->svids[pmdata->nsvids++] = svid;
>> tcpm_log(port, "SVID %d: 0x%x", pmdata->nsvids, svid);
>> }
>> - return true;
>> +
>> + /*
>> + * PD3.0 Spec 6.4.4.3.2: The SVIDs are returned 2 per VDO (see Table
>> + * 6-43), and can be returned maximum 6 VDOs per response (see Figure
>> + * 6-19). If the Respondersupports 12 or more SVID then the Discover
>> + * SVIDs Command Shall be executed multiple times until a Discover
>> + * SVIDs VDO is returned ending either with a SVID value of 0x0000 in
>> + * the last part of the last VDO or with a VDO containing two SVIDs
>> + * with values of 0x0000.
>> + *
>> + * However, some odd dockers support SVIDs less than 12 but without
>> + * 0x0000 in the last VDO, so we need to break the Discover SVIDs
>> + * request and return false here.
>> + */
>> + return cnt == 7 ? true : false;
> return cnt == 7

Okay, next to fix it.

BR.
Frank