From: Jos Wang joswang@lenovo.com

This is a workaround for STAR 4846132, which only affects DWC_usb31 version2.00a operating in host mode.

There is a problem in DWC_usb31 version 2.00a operating in host mode that would cause a CSR read timeout When CSR read coincides with RAM Clock Gating Entry. By disable Clock Gating, sacrificing power consumption for normal operation.

Cc: stable@vger.kernel.org Signed-off-by: Jos Wang joswang@lenovo.com --- v5 -> v6: no change v4 -> v5: no change v3 -> v4: modify commit message, add Cc: stable@vger.kernel.org v2 -> v3: - code refactor - modify comment, add STAR number, workaround applied in host mode - modify commit message, add STAR number, workaround applied in host mode - modify Author Jos Wang v1 -> v2: no change

drivers/usb/dwc3/core.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c index 7ee61a89520b..2a3adc80fe0f 100644 --- a/drivers/usb/dwc3/core.c +++ b/drivers/usb/dwc3/core.c @@ -957,12 +957,16 @@ static bool dwc3_core_is_valid(struct dwc3 *dwc)

static void dwc3_core_setup_global_control(struct dwc3 *dwc) { + unsigned int power_opt; + unsigned int hw_mode; u32 reg;

reg = dwc3_readl(dwc->regs, DWC3_GCTL); reg &= ~DWC3_GCTL_SCALEDOWN_MASK; + hw_mode = DWC3_GHWPARAMS0_MODE(dwc->hwparams.hwparams0); + power_opt = DWC3_GHWPARAMS1_EN_PWROPT(dwc->hwparams.hwparams1);

- switch (DWC3_GHWPARAMS1_EN_PWROPT(dwc->hwparams.hwparams1)) { + switch (power_opt) { case DWC3_GHWPARAMS1_EN_PWROPT_CLK: /** * WORKAROUND: DWC3 revisions between 2.10a and 2.50a have an @@ -995,6 +999,20 @@ static void dwc3_core_setup_global_control(struct dwc3 *dwc) break; }

+ /* + * This is a workaround for STAR#4846132, which only affects + * DWC_usb31 version2.00a operating in host mode. + * + * There is a problem in DWC_usb31 version 2.00a operating + * in host mode that would cause a CSR read timeout When CSR + * read coincides with RAM Clock Gating Entry. By disable + * Clock Gating, sacrificing power consumption for normal + * operation. + */ + if (power_opt != DWC3_GHWPARAMS1_EN_PWROPT_NO && + hw_mode != DWC3_GHWPARAMS0_MODE_GADGET && DWC3_VER_IS(DWC31, 200A)) + reg |= DWC3_GCTL_DSBLCLKGTNG; + /* check if current dwc3 is on simulation board */ if (dwc->hwparams.hwparams6 & DWC3_GHWPARAMS6_EN_FPGA) { dev_info(dwc->dev, "Running with FPGA optimizations\n");