Hi,
John Youn <John.Youn@xxxxxxxxxxxx> writes:
> On 4/28/2016 1:01 AM, Felipe Balbi wrote:
>> NumP field of DCFG register is used on NumP field of
>> ACK TP header and it tells the host how many packets
>> an endpoint can receive before waiting for
>> synchronization.
>>
>> Documentation says it should be set to anything
>> <=bMaxBurst. Interestingly, however, this setting is
>> not per-endpoint how it should be (different
>> endpoints could have different burst sizes), but
>> things seem to work okay right now.
>>
>> Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
>> ---
>> drivers/usb/dwc3/core.h | 3 +++
>> drivers/usb/dwc3/gadget.c | 14 ++++++++++++--
>> 2 files changed, 15 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
>> index 87df6dd20d23..c5f576aa1903 100644
>> --- a/drivers/usb/dwc3/core.h
>> +++ b/drivers/usb/dwc3/core.h
>> @@ -271,6 +271,9 @@
>> #define DWC3_DCFG_LOWSPEED (2 << 0)
>> #define DWC3_DCFG_FULLSPEED1 (3 << 0)
>>
>> +#define DWC3_DCFG_NUMP_SHIFT 17
>> +#define DWC3_DCFG_NUMP(n) (((n) & 0x1f) >> DWC3_DCFG_NUMP_SHIFT)
>> +#define DWC3_DCFG_NUMP_MASK (0x1f << DWC3_DCFG_NUMP_SHIFT)
>> #define DWC3_DCFG_LPM_CAP (1 << 22)
>>
>> /* Device Control Register */
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index 43efb627d1cf..4b681b0d420f 100644
>> --- a/drivers/usb/dwc3/gadget.c
>> +++ b/drivers/usb/dwc3/gadget.c
>> @@ -464,9 +464,19 @@ static int dwc3_gadget_set_ep_config(struct dwc3 *dwc, struct dwc3_ep *dep,
>>
>> /* Burst size is only needed in SuperSpeed mode */
>> if (dwc->gadget.speed >= USB_SPEED_SUPER) {
>> - u32 burst = dep->endpoint.maxburst - 1;
>> + u32 burst = dep->endpoint.maxburst;
>> + u32 nump;
>> + u32 reg;
>>
>> - params.param0 |= DWC3_DEPCFG_BURST_SIZE(burst);
>> + /* update NumP */
>> + reg = dwc3_readl(dwc->regs, DWC3_DCFG);
>> + nump = DWC3_DCFG_NUMP(reg);
>> + nump = max(nump, burst);
>> + reg &= ~DWC3_DCFG_NUMP_MASK;
>> + reg |= nump << DWC3_DCFG_NUMP_SHIFT;
>> + dwc3_writel(dwc->regs, DWC3_DCFG, reg);
>> +
>> + params.param0 |= DWC3_DEPCFG_BURST_SIZE(burst - 1);
>
> Hi Felipe,
>
> The controller already takes care not to send a NUMP greater than the
> configured maxburst for the endpoint. So there is no need to do
> this. You can just set it globally in core init.
iow, we just set this to the maximum value and forget about it ? That
doesn't appear to be documented. We can patch this up for v4.8, then
since $subject has no negative side-effect and Greg has already merged
this to his tree :-)
> NUMP actually should be a global setting because The NUMP is a
> function of the space left on the singular, global, RX fifo,
> regardless of what EP is receiving the data.
Understood :-)
--
balbi
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