Hi,
John Youn <johnyoun@xxxxxxxxxxxx> writes:
> Currently GEVNTCOUNT is written in the threaded interrupt handler while
> processing each event. This commit moves the GEVNTCOUNT write to the
> hard IRQ. We then copy the events to a separate buffer for the event
> handler to read from.
>
> This change is in preparation of working around an issue in core version
> 3.00a where the interrupt cannot be de-asserted in the normal way.
> However, if we enable interrupt moderation, we can also de-assert it by
> writing to GEVNTCOUNT.
>
> Signed-off-by: John Youn <johnyoun@xxxxxxxxxxxx>
> ---
> drivers/usb/dwc3/core.c | 4 ++++
> drivers/usb/dwc3/core.h | 2 ++
> drivers/usb/dwc3/gadget.c | 22 +++++++++++++---------
> 3 files changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index af42346..f0bb6df 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -251,6 +251,10 @@ static struct dwc3_event_buffer *dwc3_alloc_one_event_buffer(struct dwc3 *dwc,
>
> evt->dwc = dwc;
> evt->length = length;
> + evt->cache = devm_kzalloc(dwc->dev, length, GFP_KERNEL);
> + if (!evt->cache)
> + return ERR_PTR(-ENOMEM);
> +
> evt->buf = dma_alloc_coherent(dwc->dev, length,
> &evt->dma, GFP_KERNEL);
> if (!evt->buf)
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 354de24..bf63756 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -472,6 +472,7 @@ struct dwc3_trb;
> /**
> * struct dwc3_event_buffer - Software event buffer representation
> * @buf: _THE_ buffer
> + * @cache: The buffer cache used in the threaded interrupt
> * @length: size of this buffer
> * @lpos: event offset
> * @count: cache of last read event count register
> @@ -481,6 +482,7 @@ struct dwc3_trb;
> */
> struct dwc3_event_buffer {
> void *buf;
> + void *cache;
> unsigned length;
> unsigned int lpos;
> unsigned int count;
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 22ccc34..f07dd84 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2829,18 +2829,16 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt)
> {
> struct dwc3 *dwc = evt->dwc;
> irqreturn_t ret = IRQ_NONE;
> - int left;
> + int idx;
> u32 reg;
>
> - left = evt->count;
> -
> if (!(evt->flags & DWC3_EVENT_PENDING))
> return IRQ_NONE;
>
> - while (left > 0) {
> + for (idx = 0; idx < evt->count; idx += 4) {
why so many changes on the same patch? Why did you remove left and
evt->lpos? You can still use both for traversing through your cache,
right?
> union dwc3_event event;
>
> - event.raw = *(u32 *) (evt->buf + evt->lpos);
> + event.raw = *(u32 *)(evt->cache + idx);
>
> dwc3_process_event_entry(dwc, &event);
>
> @@ -2853,10 +2851,6 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt)
> * boundary so I worry about that once we try to handle
> * that.
> */
> - evt->lpos = (evt->lpos + 4) % DWC3_EVENT_BUFFERS_SIZE;
> - left -= 4;
> -
> - dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), 4);
> }
>
> evt->count = 0;
> @@ -2889,6 +2883,7 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
> {
> struct dwc3 *dwc = evt->dwc;
> u32 count;
> + u32 amount;
please keep reverse xmas tree ordering ;-)
> u32 reg;
>
> if (pm_runtime_suspended(dwc->dev)) {
> @@ -2906,6 +2901,15 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt)
> evt->count = count;
> evt->flags |= DWC3_EVENT_PENDING;
>
> + amount = min(count, DWC3_EVENT_BUFFERS_SIZE - evt->lpos);
> + memcpy(evt->cache, evt->buf + evt->lpos, amount);
> +
> + if (amount < count)
> + memcpy(evt->cache + amount, evt->buf, count - amount);
> +
> + evt->lpos = (evt->lpos + count) % DWC3_EVENT_BUFFERS_SIZE;
evt->lpos is only for the driver, if you don't touch it here you can
still use it on the bottom half handler.
> + dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), count);
should you mask first just to make sure we don't have other interrupts
as soon as we clear the ones we just read?
--
balbi
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