Robert Hancock wrote: > Previously a device tree property was added to allow overriding the > reference clock period parameter if the default value used was incorrect. > However, there is another register field, GFLADJ_REFCLK_FLADJ, which > reflects the fractional nanosecond portion of the reference clock > period. Add a snps,ref-clock-fladj property to allow configuring this > as well. > > On the Xilinx ZynqMP platform, the reference clock appears to always > be 20 MHz, giving a clock period of 50 ns. However, the default value > of GFLADJ_REFCLK_FLADJ was 1008 rather than 0 as it should have been, > which prevented many USB devices from functioning properly. The > psu_init code run by the Xilinx first-stage boot loader sets this > value to 0, however when the controller is reset by the dwc3-xilinx > layer, the incorrect default value is restored. This configuration > property allows ensuring that the correct value is always used. > > Signed-off-by: Robert Hancock <robert.hancock@xxxxxxxxxx> > --- > drivers/usb/dwc3/core.c | 35 +++++++++++++++++++++++++++++++++++ > drivers/usb/dwc3/core.h | 3 +++ > 2 files changed, 38 insertions(+) > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c > index f4c09951b517..ea11fd1e3b42 100644 > --- a/drivers/usb/dwc3/core.c > +++ b/drivers/usb/dwc3/core.c > @@ -359,6 +359,37 @@ static void dwc3_ref_clk_period(struct dwc3 *dwc) > } > > > +/** > + * dwc3_ref_clk_fladj - Reference clock period adjustment configuration > + * GFLADJ_REFCLK_FLADJ should be set based on the fractional portion of the > + * reference clock period, where the integer portion is set in GUCTL_REFCLKPER. > + * Calculated as: ((125000/ref_clk_period_integer)-(125000/ref_clk_period)) * ref_clk_period > + * where ref_clk_period_integer is the period specified in GUCTL_REFCLKPER and > + * ref_clk_period is the period including fractional value. > + * This value can be specified in the device tree if the default value is incorrect. > + * Note that 0 is a valid value. Minor nit. Can you follow the kernel-doc format for brief/long description https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.html > + * > + * @dwc3: Pointer to our controller context structure > + */ > +static void dwc3_ref_clk_fladj(struct dwc3 *dwc) > +{ > + u32 reg; > + u32 reg_new; > + > + if (DWC3_VER_IS_PRIOR(DWC3, 250A)) > + return; > + > + if (!dwc->ref_clk_fladj_set) > + return; > + > + reg = dwc3_readl(dwc->regs, DWC3_GFLADJ); > + reg_new = reg & ~DWC3_GFLADJ_REFCLK_FLADJ_MASK; > + reg_new |= FIELD_PREP(DWC3_GFLADJ_REFCLK_FLADJ_MASK, dwc->ref_clk_fladj); > + if (reg_new != reg) > + dwc3_writel(dwc->regs, DWC3_GFLADJ, reg_new); > +} > + > + > /** > * dwc3_free_one_event_buffer - Frees one event buffer > * @dwc: Pointer to our controller context structure > @@ -1033,6 +1064,7 @@ static int dwc3_core_init(struct dwc3 *dwc) > > /* Adjust Reference Clock Period */ > dwc3_ref_clk_period(dwc); > + dwc3_ref_clk_fladj(dwc); > > dwc3_set_incr_burst_type(dwc); > > @@ -1418,6 +1450,9 @@ static void dwc3_get_properties(struct dwc3 *dwc) > &dwc->fladj); > device_property_read_u32(dev, "snps,ref-clock-period-ns", > &dwc->ref_clk_per); > + if (!device_property_read_u32(dev, "snps,ref-clock-fladj", > + &dwc->ref_clk_fladj)) > + dwc->ref_clk_fladj_set = true; > > dwc->dis_metastability_quirk = device_property_read_bool(dev, > "snps,dis_metastability_quirk"); > diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h > index e1cc3f7398fb..650d4c2e7a67 100644 > --- a/drivers/usb/dwc3/core.h > +++ b/drivers/usb/dwc3/core.h > @@ -388,6 +388,7 @@ > /* Global Frame Length Adjustment Register */ > #define DWC3_GFLADJ_30MHZ_SDBND_SEL BIT(7) > #define DWC3_GFLADJ_30MHZ_MASK 0x3f > +#define DWC3_GFLADJ_REFCLK_FLADJ_MASK 0x3fff00 > > /* Global User Control Register*/ > #define DWC3_GUCTL_REFCLKPER_MASK 0xffc00000 > @@ -1166,6 +1167,8 @@ struct dwc3 { > > u32 fladj; > u32 ref_clk_per; > + bool ref_clk_fladj_set; > + u32 ref_clk_fladj; Can you also document these new struct members. > u32 irq_gadget; > u32 otg_irq; > u32 current_otg_role; For this patch: Reviewed-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> Thanks! Thinh
