On Thu, Nov 10, 2022 at 1:38 PM Pawel Laszczak pawell@cadence.com wrote:
On Mon, Nov 7, 2022 at 1:39 PM Pawel Laszczak pawell@cadence.com wrote:
On 22-10-27 08:46:17, Pawel Laszczak wrote:
> >On 22-10-24 10:04:35, Pawel Laszczak wrote: >> Patch modifies the TD_SIZE in TRB before ZLP TRB. >> The TD_SIZE in TRB before ZLP TRB must be set to 1 to force >> processing ZLP TRB by controller. >> >> cc: stable@vger.kernel.org >> Fixes: 3d82904559f4 ("usb: cdnsp: cdns3 Add main part of >> Cadence USBSSP DRD Driver") >> Signed-off-by: Pawel Laszczak pawell@cadence.com >> >> --- >> Changelog: >> v2: >> - returned value for last TRB must be 0 >> >> drivers/usb/cdns3/cdnsp-ring.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/usb/cdns3/cdnsp-ring.c >> b/drivers/usb/cdns3/cdnsp-ring.c index >> 04dfcaa08dc4..aa79bce89d8a >> 100644 >> --- a/drivers/usb/cdns3/cdnsp-ring.c >> +++ b/drivers/usb/cdns3/cdnsp-ring.c >> @@ -1769,8 +1769,13 @@ static u32 cdnsp_td_remainder(struct >> cdnsp_device *pdev, >> >> /* One TRB with a zero-length data packet. */ >> if (!more_trbs_coming || (transferred == 0 && trb_buff_len == 0)
||
>> - trb_buff_len == td_total_len) >> + trb_buff_len == td_total_len) { >> + /* Before ZLP driver needs set TD_SIZE=1. */ >> + if (more_trbs_coming) >> + return 1; >> + >> return 0; >> + } > >Does that fix the issue you want at bulk transfer, which has >zero-length packet at the last packet? It seems not align with >your previous
fix.
>Would you mind explaining more?
Value returned by function cdnsp_td_remainder is used as TD_SIZE in TRB.
The last TRB in TD should have TD_SIZE=0, so trb for ZLP should have set also TD_SIZE=0. If driver set TD_SIZE=0 on before the last one TRB then the controller stops the transfer and ignore trb for ZLP
packet.
To fix this, the driver in such case must set TD_SIZE = 1 before the last TRB.
if (!more_trbs_coming || (transferred == 0 && trb_buff_len == 0)||
trb_buff_len == td_total_len)
trb_buff_len == td_total_len) {/* Before ZLP driver needs set TD_SIZE=1. */if (more_trbs_coming)return 1;return 0;}How your above fix could return TD_SIZE as 1 for last non-ZLP TRB? Which conditions are satisfied?
For last non-ZLP TRB TD_SIZE should be 0 or 1.
We have three casess:
TRB1 - length > 1 TRb2 - ZLPIn this case TRB1 should have set TD_SIZE = 1. In this case the condition if (more_trbs_coming) return 1;
returns TD_SIZE=1. In this case more_trb_comming for TRB1 is 1 and for TRB2 is 0
This one is my question. How below condition is true for your case 1:
if (!more_trbs_coming || (transferred == 0 && trb_buff_len == 0) || trb_buff_len == td_total_len)
For TRB1: more_trbs_coming = true transferred == 0 && trb_buff_len == 0 - false - it does not matter in this
case
trb_buff_len == td_total_len - true
Why trb_buff_len equals to td_total_length? Considering the bulk transfer with request length larger than 64KB.
You have right, there might still be a problem with ZLP. I've posted the v3 implemented a little differently.
Thanks Pawel
so whole condition is true.
Because more_trb_comming = true so: if (more_trbs_coming) return 1; returns TD_SIZE = 1
For TRB2 - ZLP: more_trbs_coming = false transferred == 0 && trb_buff_len == 0 - false - it does not matter in this
case
trb_buff_len == td_total_len - true
Because more_trb_comming = false so function returns TD_SIZE = 0 for
last ZLP trb.
Pawel