Hi,
Janusz Dziedzic <janusz.dziedzic@xxxxxxxxx> writes:
> On 15 November 2016 at 12:23, Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> wrote:
>> From: John Youn <johnyoun@xxxxxxxxxxxx>
>>
>> Let's start copying events from evt->buf to
>> evt->cache and use evt->cache for processing events.
>>
>> A follow-up patch will be added to clear events in
>> the top-half handler in order to bring IRQ line low
>> as soon as possible.
>>
>> Signed-off-by: John Youn <johnyoun@xxxxxxxxxxxx>
>> Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
>> ---
>> drivers/usb/dwc3/gadget.c | 9 ++++++++-
>> 1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index 304653fd9223..0481cb7d7142 100644
>> --- a/drivers/usb/dwc3/gadget.c
>> +++ b/drivers/usb/dwc3/gadget.c
>> @@ -2821,7 +2821,7 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt)
>> while (left > 0) {
>> union dwc3_event event;
>>
>> - event.raw = *(u32 *) (evt->buf + evt->lpos);
>> + event.raw = *(u32 *) (evt->cache + evt->lpos);
>>
>> dwc3_process_event_entry(dwc, &event);
>>
>> @@ -2869,6 +2869,7 @@ static irqreturn_t dwc3_thread_interrupt(int irq, void *_evt)
>> static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
>> {
>> struct dwc3 *dwc = evt->dwc;
>> + u32 amount;
>> u32 count;
>> u32 reg;
>>
>> @@ -2892,6 +2893,12 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
>> reg |= DWC3_GEVNTSIZ_INTMASK;
>> dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg);
>>
>> + amount = min(count, evt->length - evt->lpos);
>> + memcpy(evt->cache + evt->lpos, evt->buf + evt->lpos, amount);
>> +
> Why not just:
> memcpy(evt->cache, evt->buf + evt->lpos, count)
> And always handle evt->cache[0 ... count] in thread_interrupt.
This won't always work. evt->buf is treated by HW as a ring buffer, so
if count + lpos > length, then we would copy from outside our event
buffer.
--
balbi
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