| Message ID | 20250216223003.3568039-1-badhri@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] usb: dwc3: gadget: Prevent irq storm when TH re-executes | expand |
On Sun, Feb 16, 2025, Badhri Jagan Sridharan wrote: > While commit d325a1de49d6 ("usb: dwc3: gadget: Prevent losing events in > event cache") makes sure that top half(TH) does not end up overwriting the > cached events before processing them when the TH gets invoked more than one > time, returning IRQ_HANDLED results in occasional irq storm where the TH > hogs the CPU. The irq storm can be prevented by the flag before event > handler busy is cleared. Default enable interrupt moderation in all > versions which support them. > > ftrace event stub during dwc3 irq storm: > irq/504_dwc3-1111 ( 1111) [000] .... 70.000866: irq_handler_exit: irq=14 ret=handled > irq/504_dwc3-1111 ( 1111) [000] .... 70.000872: irq_handler_entry: irq=504 name=dwc3 > irq/504_dwc3-1111 ( 1111) [000] .... 70.000874: irq_handler_exit: irq=504 ret=handled > irq/504_dwc3-1111 ( 1111) [000] .... 70.000881: irq_handler_entry: irq=504 name=dwc3 > irq/504_dwc3-1111 ( 1111) [000] .... 70.000883: irq_handler_exit: irq=504 ret=handled > irq/504_dwc3-1111 ( 1111) [000] .... 70.000889: irq_handler_entry: irq=504 name=dwc3 > irq/504_dwc3-1111 ( 1111) [000] .... 70.000892: irq_handler_exit: irq=504 ret=handled > irq/504_dwc3-1111 ( 1111) [000] .... 70.000898: irq_handler_entry: irq=504 name=dwc3 > irq/504_dwc3-1111 ( 1111) [000] .... 70.000901: irq_handler_exit: irq=504 ret=handled > irq/504_dwc3-1111 ( 1111) [000] .... 70.000907: irq_handler_entry: irq=504 name=dwc3 > irq/504_dwc3-1111 ( 1111) [000] .... 70.000909: irq_handler_exit: irq=504 ret=handled > irq/504_dwc3-1111 ( 1111) [000] .... 70.000915: irq_handler_entry: irq=504 name=dwc3 > irq/504_dwc3-1111 ( 1111) [000] .... 70.000918: irq_handler_exit: irq=504 ret=handled > irq/504_dwc3-1111 ( 1111) [000] .... 70.000924: irq_handler_entry: irq=504 name=dwc3 > irq/504_dwc3-1111 ( 1111) [000] .... 70.000927: irq_handler_exit: irq=504 ret=handled > irq/504_dwc3-1111 ( 1111) [000] .... 70.000933: irq_handler_entry: irq=504 name=dwc3 > irq/504_dwc3-1111 ( 1111) [000] .... 70.000935: irq_handler_exit: irq=504 ret=handled > .... > > Cc: stable@kernel.org > Suggested-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com> > Fixes: d325a1de49d6 ("usb: dwc3: gadget: Prevent losing events in event cache") > Signed-off-by: Badhri Jagan Sridharan <badhri@google.com> > --- > Changes since v2: > * Consolidate logic for default enabling interrupt moderation as suggested > by Thinh.Nguyen@ > --- > drivers/usb/dwc3/core.c | 16 ++++++---------- > drivers/usb/dwc3/gadget.c | 10 +++++++--- > 2 files changed, 13 insertions(+), 13 deletions(-) > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c > index dfa1b5fe48dc..2c472cb97f6c 100644 > --- a/drivers/usb/dwc3/core.c > +++ b/drivers/usb/dwc3/core.c > @@ -1835,8 +1835,6 @@ static void dwc3_get_properties(struct dwc3 *dwc) > dwc->tx_thr_num_pkt_prd = tx_thr_num_pkt_prd; > dwc->tx_max_burst_prd = tx_max_burst_prd; > > - dwc->imod_interval = 0; > - > dwc->tx_fifo_resize_max_num = tx_fifo_resize_max_num; > } > > @@ -1854,21 +1852,19 @@ static void dwc3_check_params(struct dwc3 *dwc) > unsigned int hwparam_gen = > DWC3_GHWPARAMS3_SSPHY_IFC(dwc->hwparams.hwparams3); > > - /* Check for proper value of imod_interval */ > - if (dwc->imod_interval && !dwc3_has_imod(dwc)) { > - dev_warn(dwc->dev, "Interrupt moderation not supported\n"); > - dwc->imod_interval = 0; > - } > - > /* > + * Enable IMOD for all supporting controllers. > + * > + * Particularly, DWC_usb3 v3.00a must enable this feature for > + * the following reason: > + * > * Workaround for STAR 9000961433 which affects only version > * 3.00a of the DWC_usb3 core. This prevents the controller > * interrupt from being masked while handling events. IMOD > * allows us to work around this issue. Enable it for the > * affected version. > */ > - if (!dwc->imod_interval && > - DWC3_VER_IS(DWC3, 300A)) > + if (dwc3_has_imod((dwc))) > dwc->imod_interval = 1; > > /* Check the maximum_speed parameter */ > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c > index d27af65eb08a..fad115113d28 100644 > --- a/drivers/usb/dwc3/gadget.c > +++ b/drivers/usb/dwc3/gadget.c > @@ -4467,14 +4467,18 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt) > dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), > DWC3_GEVNTSIZ_SIZE(evt->length)); > > + evt->flags &= ~DWC3_EVENT_PENDING; > + /* > + * Add an explicit write memory barrier to make sure that the update of > + * clearing DWC3_EVENT_PENDING is observed in dwc3_check_event_buf() > + */ > + wmb(); > + > if (dwc->imod_interval) { > dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), DWC3_GEVNTCOUNT_EHB); > dwc3_writel(dwc->regs, DWC3_DEV_IMOD(0), dwc->imod_interval); > } > > - /* Keep the clearing of DWC3_EVENT_PENDING at the end */ > - evt->flags &= ~DWC3_EVENT_PENDING; > - > return ret; > } > > > base-commit: 9682c35ff6ecd76d9462d4749b8b413d3e8e605e > -- > 2.48.1.601.g30ceb7b040-goog > Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com> Thanks, Thinh
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c index dfa1b5fe48dc..2c472cb97f6c 100644 --- a/drivers/usb/dwc3/core.c +++ b/drivers/usb/dwc3/core.c @@ -1835,8 +1835,6 @@ static void dwc3_get_properties(struct dwc3 *dwc) dwc->tx_thr_num_pkt_prd = tx_thr_num_pkt_prd; dwc->tx_max_burst_prd = tx_max_burst_prd; - dwc->imod_interval = 0; - dwc->tx_fifo_resize_max_num = tx_fifo_resize_max_num; } @@ -1854,21 +1852,19 @@ static void dwc3_check_params(struct dwc3 *dwc) unsigned int hwparam_gen = DWC3_GHWPARAMS3_SSPHY_IFC(dwc->hwparams.hwparams3); - /* Check for proper value of imod_interval */ - if (dwc->imod_interval && !dwc3_has_imod(dwc)) { - dev_warn(dwc->dev, "Interrupt moderation not supported\n"); - dwc->imod_interval = 0; - } - /* + * Enable IMOD for all supporting controllers. + * + * Particularly, DWC_usb3 v3.00a must enable this feature for + * the following reason: + * * Workaround for STAR 9000961433 which affects only version * 3.00a of the DWC_usb3 core. This prevents the controller * interrupt from being masked while handling events. IMOD * allows us to work around this issue. Enable it for the * affected version. */ - if (!dwc->imod_interval && - DWC3_VER_IS(DWC3, 300A)) + if (dwc3_has_imod((dwc))) dwc->imod_interval = 1; /* Check the maximum_speed parameter */ diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index d27af65eb08a..fad115113d28 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -4467,14 +4467,18 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt) dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), DWC3_GEVNTSIZ_SIZE(evt->length)); + evt->flags &= ~DWC3_EVENT_PENDING; + /* + * Add an explicit write memory barrier to make sure that the update of + * clearing DWC3_EVENT_PENDING is observed in dwc3_check_event_buf() + */ + wmb(); + if (dwc->imod_interval) { dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), DWC3_GEVNTCOUNT_EHB); dwc3_writel(dwc->regs, DWC3_DEV_IMOD(0), dwc->imod_interval); } - /* Keep the clearing of DWC3_EVENT_PENDING at the end */ - evt->flags &= ~DWC3_EVENT_PENDING; - return ret; }
While commit d325a1de49d6 ("usb: dwc3: gadget: Prevent losing events in event cache") makes sure that top half(TH) does not end up overwriting the cached events before processing them when the TH gets invoked more than one time, returning IRQ_HANDLED results in occasional irq storm where the TH hogs the CPU. The irq storm can be prevented by the flag before event handler busy is cleared. Default enable interrupt moderation in all versions which support them. ftrace event stub during dwc3 irq storm: irq/504_dwc3-1111 ( 1111) [000] .... 70.000866: irq_handler_exit: irq=14 ret=handled irq/504_dwc3-1111 ( 1111) [000] .... 70.000872: irq_handler_entry: irq=504 name=dwc3 irq/504_dwc3-1111 ( 1111) [000] .... 70.000874: irq_handler_exit: irq=504 ret=handled irq/504_dwc3-1111 ( 1111) [000] .... 70.000881: irq_handler_entry: irq=504 name=dwc3 irq/504_dwc3-1111 ( 1111) [000] .... 70.000883: irq_handler_exit: irq=504 ret=handled irq/504_dwc3-1111 ( 1111) [000] .... 70.000889: irq_handler_entry: irq=504 name=dwc3 irq/504_dwc3-1111 ( 1111) [000] .... 70.000892: irq_handler_exit: irq=504 ret=handled irq/504_dwc3-1111 ( 1111) [000] .... 70.000898: irq_handler_entry: irq=504 name=dwc3 irq/504_dwc3-1111 ( 1111) [000] .... 70.000901: irq_handler_exit: irq=504 ret=handled irq/504_dwc3-1111 ( 1111) [000] .... 70.000907: irq_handler_entry: irq=504 name=dwc3 irq/504_dwc3-1111 ( 1111) [000] .... 70.000909: irq_handler_exit: irq=504 ret=handled irq/504_dwc3-1111 ( 1111) [000] .... 70.000915: irq_handler_entry: irq=504 name=dwc3 irq/504_dwc3-1111 ( 1111) [000] .... 70.000918: irq_handler_exit: irq=504 ret=handled irq/504_dwc3-1111 ( 1111) [000] .... 70.000924: irq_handler_entry: irq=504 name=dwc3 irq/504_dwc3-1111 ( 1111) [000] .... 70.000927: irq_handler_exit: irq=504 ret=handled irq/504_dwc3-1111 ( 1111) [000] .... 70.000933: irq_handler_entry: irq=504 name=dwc3 irq/504_dwc3-1111 ( 1111) [000] .... 70.000935: irq_handler_exit: irq=504 ret=handled .... Cc: stable@kernel.org Suggested-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com> Fixes: d325a1de49d6 ("usb: dwc3: gadget: Prevent losing events in event cache") Signed-off-by: Badhri Jagan Sridharan <badhri@google.com> --- Changes since v2: * Consolidate logic for default enabling interrupt moderation as suggested by Thinh.Nguyen@ --- drivers/usb/dwc3/core.c | 16 ++++++---------- drivers/usb/dwc3/gadget.c | 10 +++++++--- 2 files changed, 13 insertions(+), 13 deletions(-) base-commit: 9682c35ff6ecd76d9462d4749b8b413d3e8e605e