6.6-stable review patch. If anyone has any objections, please let me know.
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From: Badhri Jagan Sridharan badhri@google.com
commit 69c58deec19628c8a686030102176484eb94fed4 upstream.
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 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 Acked-by: Thinh Nguyen Thinh.Nguyen@synopsys.com Link: https://lore.kernel.org/r/20250216223003.3568039-1-badhri@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/dwc3/core.c | 16 ++++++---------- drivers/usb/dwc3/gadget.c | 10 +++++++--- 2 files changed, 13 insertions(+), 13 deletions(-)
--- a/drivers/usb/dwc3/core.c +++ b/drivers/usb/dwc3/core.c @@ -1671,8 +1671,6 @@ static void dwc3_get_properties(struct d 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; }
@@ -1690,21 +1688,19 @@ static void dwc3_check_params(struct 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 */ --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -4507,14 +4507,18 @@ static irqreturn_t dwc3_process_event_bu 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; }