[PATCH v3, 3/3] usb: dwc3: core: Workaround for CSR read timeout

joswang
2024-06-11T14:29:58Z

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.

Signed-off-by: Jos Wang <joswang@lenovo.com>
---
v1 -> v2:
- add "dt-bindings: usb: dwc3: Add snps,p2p3tranok quirk" patch
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
---
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 3a8fbc2d6b99..61f858f64e5a 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -960,12 +960,16 @@ 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
@@ -998,6 +1002,20 @@ 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");
--
2.17.1