Hi,
Jack Pham <jackp@xxxxxxxxxxxxxx> writes:
> commit 72704f876f50 ("dwc3: gadget: Implement the suspend entry event
> handler") introduced (nearly 5 years ago!) an interrupt handler for
> U3/L1-L2 suspend events. The problem is that these events aren't
look deeper. They *were* enabled. We've removed because, as it turns
out, they just add a TON of interrupts and don't give us much extra
information. The only reason why the state change interrupts are still
there is because of a known silicon bug in versions < 2.50a. That's all
documented in the driver itself.
For anything that works, we *don't* want link state change interrupts.
> currently enabled in the DEVTEN register so the handler is never
> even invoked. Fix this simply by enabling the corresponding bit
> in dwc3_gadget_enable_irq() using the same revision check as found
> in the handler.
More importantly, *why* do you think you need these interrupts?
> Fixes: 72704f876f50 ("dwc3: gadget: Implement the suspend entry event handler")
> Signed-off-by: Jack Pham <jackp@xxxxxxxxxxxxxx>
> ---
> drivers/usb/dwc3/gadget.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index dd80e5ca8c78..cab3a9184068 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2323,6 +2323,10 @@ static void dwc3_gadget_enable_irq(struct dwc3 *dwc)
> if (DWC3_VER_IS_PRIOR(DWC3, 250A))
> reg |= DWC3_DEVTEN_ULSTCNGEN;
>
> + /* On 2.30a and above this bit enables U3/L2-L1 Suspend Events */
> + if (!DWC3_VER_IS_PRIOR(DWC3, 230A))
> + reg |= DWC3_DEVTEN_EOPFEN;
look at cpu usage for dwc3's interrupt before and after this
IRQ. Specially when connected to a host that fully supports LPM. IIRC,
recent xhci should trigger state changes fairly often.
Still, why do you think you need these events?
--
balbi
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