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SubjectRe: [PATCH v2 2/2] usb: dwc3: Add workaround for host mode VBUS glitch when boot
On Tue, Feb 19, 2019 at 1:24 AM Ran Wang <ran.wang_1@nxp.com> wrote:
>
> When DWC3 is set to host mode by programming register DWC3_GCTL, VBUS
> (or its control signal) will be turned on immediately on related Root Hub
> ports. Then, the VBUS is turned off for a little while(15us) when do xhci
> reset (conducted by xhci driver) and back to normal finally, we can
> observe a negative glitch of related signal happen.
>
> This VBUS glitch might cause some USB devices enumeration fail if kernel
> boot with them connected. Such as LS1012AFWRY/LS1043ARDB/LX2160AQDS
> /LS1088ARDB with Kingston 16GB USB2.0/Kingston USB3.0/JetFlash Transcend
> 4GB USB2.0 drives. The fail cases include enumerated as full-speed device
> or report wrong device descriptor, etc.
>
> One SW workaround which can fix this is by programing all xhci PORTSC[PP]
> to 0 to turn off VBUS immediately after setting host mode in DWC3 driver
> (per signal measurement result, it will be too late to do it in
> xhci-plat.c or xhci.c). Then, after xhci reset complete in xhci driver,
> PORTSC[PP]s' value will back to 1 automatically and VBUS on at that time,
> no glitch happen and normal enumeration process has no impact.
>
> Signed-off-by: Ran Wang <ran.wang_1@nxp.com>
> ---
> Changes in v2:
> - Rename related property to 'snps,host-vbus-glitches'
> - Rename related dwc member to 'host_vbus_glitches'
> - Add member 'host_vbus_glitches' description in 'dwc3'
>
> drivers/usb/dwc3/core.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
> drivers/usb/dwc3/core.h | 12 +++++++++++-
> 2 files changed, 58 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index a1b126f..02d11bc 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -100,6 +100,41 @@ static int dwc3_get_dr_mode(struct dwc3 *dwc)
> return 0;
> }
>
> +/*
> + * dwc3_power_of_all_roothub_ports - Power off all Root hub ports
> + * @dwc3: Pointer to our controller context structure
> + */
> +static void dwc3_power_off_all_roothub_ports(struct dwc3 *dwc)
> +{
> + int i, port_num;
> + u32 reg, op_regs_base, offset;
> + void __iomem *xhci_regs;
> +
> + /* xhci regs is not mapped yet, do it temperary here */
> + if (dwc->xhci_resources[0].start) {
> + xhci_regs = ioremap(dwc->xhci_resources[0].start,
> + DWC3_XHCI_REGS_END);
> + if (IS_ERR(xhci_regs)) {
> + dev_err(dwc->dev, "Failed to ioremap xhci_regs\n");
> + return;
> + }
> +
> + op_regs_base = HC_LENGTH(readl(xhci_regs));
> + reg = readl(xhci_regs + XHCI_HCSPARAMS1);
> + port_num = HCS_MAX_PORTS(reg);
> +
> + for (i = 1; i <= port_num; i++) {
> + offset = op_regs_base + XHCI_PORTSC_BASE + 0x10*(i-1);

Define the 0x10 as macro? And why don't you have the initial value of
i loop to be 0 to avoid the (i-1) here?

> + reg = readl(xhci_regs + offset);
> + reg &= ~PORT_POWER;
> + writel(reg, xhci_regs + offset);
> + }
> +
> + iounmap(xhci_regs);
> + } else
> + dev_err(dwc->dev, "xhci base reg invalid\n");
> +}
> +
> void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode)
> {
> u32 reg;
> @@ -109,6 +144,15 @@ void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode)
> reg |= DWC3_GCTL_PRTCAPDIR(mode);
> dwc3_writel(dwc->regs, DWC3_GCTL, reg);
>
> + /*
> + * We have to power off all Root hub ports immediately after DWC3 set
> + * to host mode to avoid VBUS glitch happen when xhci get reset later.
> + */
> + if (dwc->host_vbus_glitches) {
> + if (mode == DWC3_GCTL_PRTCAP_HOST)
> + dwc3_power_off_all_roothub_ports(dwc);
> + }
> +
> dwc->current_dr_role = mode;
> }
>
> @@ -1306,6 +1350,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
> dwc->dis_metastability_quirk = device_property_read_bool(dev,
> "snps,dis_metastability_quirk");
>
> + dwc->host_vbus_glitches = device_property_read_bool(dev,
> + "snps,host-vbus-glitches");
> +
> dwc->lpm_nyet_threshold = lpm_nyet_threshold;
> dwc->tx_de_emphasis = tx_de_emphasis;
>
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index df87641..9b3a7ed 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -606,6 +606,14 @@
> #define DWC3_OSTS_VBUSVLD BIT(1)
> #define DWC3_OSTS_CONIDSTS BIT(0)
>
> +/* Partial XHCI Register and Bit fields for quirk */
> +#define XHCI_HCSPARAMS1 0x4
> +#define XHCI_PORTSC_BASE 0x400
> +#define PORT_POWER (1 << 9)
> +#define HCS_MAX_PORTS(p) (((p) >> 24) & 0x7f)
> +#define XHCI_HC_LENGTH(p) (((p)>>00)&0x00ff)
> +#define HC_LENGTH(p) XHCI_HC_LENGTH(p)
> +
> /* Structures */
>
> struct dwc3_trb;
> @@ -1024,6 +1032,8 @@ struct dwc3_scratchpad_array {
> * 2 - No de-emphasis
> * 3 - Reserved
> * @dis_metastability_quirk: set to disable metastability quirk.
> + * @host-vbus-glitches: set to avoid vbus glitch during
> + * xhci reset.
> * @imod_interval: set the interrupt moderation interval in 250ns
> * increments or 0 to disable.
> */
> @@ -1209,6 +1219,7 @@ struct dwc3 {
> unsigned tx_de_emphasis:2;
>
> unsigned dis_metastability_quirk:1;
> + unsigned host_vbus_glitches:1;
>
> u16 imod_interval;
> };
> @@ -1217,7 +1228,6 @@ struct dwc3 {
> #define INCRX_UNDEF_LENGTH_BURST_MODE 1
>
> #define work_to_dwc(w) (container_of((w), struct dwc3, drd_work))
> -

No need to remove the new line here.

> /* -------------------------------------------------------------------------- */
>
> struct dwc3_event_type {
> --
> 1.7.1
>


--
- Leo

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