On 2/1/2025 5:45 AM, Thinh Nguyen wrote:
> On Fri, Jan 31, 2025, Selvarasu Ganesan wrote:
>> There is a frequent timeout during controller enter/exit from halt state
>> after toggling the run_stop bit by SW. This timeout occurs when
>> performing frequent role switches between host and device, causing
>> device enumeration issues due to the timeout. This issue was not present
>> when USB2 suspend PHY was disabled by passing the SNPS quirks
>> (snps,dis_u2_susphy_quirk and snps,dis_enblslpm_quirk) from the DTS.
>> However, there is a requirement to enable USB2 suspend PHY by setting of
>> GUSB2PHYCFG.ENBLSLPM and GUSB2PHYCFG.SUSPHY bits when controller starts
>> in gadget or host mode results in the timeout issue.
>>
>> This commit addresses this timeout issue by ensuring that the bits
>> GUSB2PHYCFG.ENBLSLPM and GUSB2PHYCFG.SUSPHY are cleared before starting
>> the dwc3_gadget_run_stop sequence and restoring them after the
>> dwc3_gadget_run_stop sequence is completed.
>>
>> Fixes: 72246da40f37 ("usb: Introduce DesignWare USB3 DRD Driver")
>> Cc: stable@xxxxxxxxxxxxxxx
>> Signed-off-by: Selvarasu Ganesan <selvarasu.g@xxxxxxxxxxx>
>> ---
>> drivers/usb/dwc3/gadget.c | 21 +++++++++++++++++++++
>> 1 file changed, 21 insertions(+)
>>
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index d27af65eb08a..4a158f703d64 100644
>> --- a/drivers/usb/dwc3/gadget.c
>> +++ b/drivers/usb/dwc3/gadget.c
>> @@ -2629,10 +2629,25 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on)
>> {
>> u32 reg;
>> u32 timeout = 2000;
>> + u32 saved_config = 0;
>>
>> if (pm_runtime_suspended(dwc->dev))
>> return 0;
>>
> Can you add some comments here that this was added through experiment
> since it is not documented in the programming guide. It would be great
> to also note which platform you used to test this with.
>
>> + reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
>> + if (unlikely(reg & DWC3_GUSB2PHYCFG_SUSPHY)) {
> I know we have "unlikely" in the other check, but we should not need it
> here or the other place. Please remove this here.
Hi Thinh,
Thanks for your review comments. I updated below newer version with
addressed your comments. Please review it.
https://lore.kernel.org/linux-usb/20250201163903.459-1-selvarasu.g@xxxxxxxxxxx/
Thanks,
Selva
>> + saved_config |= DWC3_GUSB2PHYCFG_SUSPHY;
>> + reg &= ~DWC3_GUSB2PHYCFG_SUSPHY;
>> + }
>> +
>> + if (reg & DWC3_GUSB2PHYCFG_ENBLSLPM) {
>> + saved_config |= DWC3_GUSB2PHYCFG_ENBLSLPM;
>> + reg &= ~DWC3_GUSB2PHYCFG_ENBLSLPM;
>> + }
>> +
>> + if (saved_config)
>> + dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
>> +
>> reg = dwc3_readl(dwc->regs, DWC3_DCTL);
>> if (is_on) {
>> if (DWC3_VER_IS_WITHIN(DWC3, ANY, 187A)) {
>> @@ -2660,6 +2675,12 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on)
>> reg &= DWC3_DSTS_DEVCTRLHLT;
>> } while (--timeout && !(!is_on ^ !reg));
>>
>> + if (saved_config) {
>> + reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
>> + reg |= saved_config;
>> + dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
>> + }
>> +
>> if (!timeout)
>> return -ETIMEDOUT;
>>
>> --
>> 2.17.1
>>
> Thanks,
> Thinh
