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Date: Wed, 10 Apr 2019 09:40:59 +0000
From: Ran Wang <ran.wang_1@....com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Felipe Balbi <balbi@...nel.org>
CC: "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Yang Li <pku.leo@...il.com>
Subject: RE: [PATCH v3 2/2] usb: dwc3: Add workaround for host mode VBUS
glitch when boot
Hello Sirs,
May I have your comment on this version patch, please? Thanks.
Regards,
Ran
On Tuesday, February 26, 2019 14:59, Ran Wang 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@....com>
> ---
> Changes in v3:
> - Add macro PORT_REGS_SIZE to replace 0x10
> - Change initial value of i to 0 for the for loop
> - Cosmetic changes
>
> 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 | 48
> +++++++++++++++++++++++++++++++++++++++++++++++
> drivers/usb/dwc3/core.h | 12 +++++++++++
> 2 files changed, 60 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c index
> a1b126f..dd80e3d 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -100,6 +100,42 @@ 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 = 0; i < port_num; i++) {
> + offset = op_regs_base + XHCI_PORTSC_BASE +
> + PORT_REGS_SIZE * i;
> + 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 +145,15 @@ 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 +1351,9 @@ 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..c2dee0b 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -606,6 +606,15 @@
> #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_REGS_SIZE 0x10
> +#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 +1033,8 @@ 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 +1220,7 @@ struct dwc3 {
> unsigned tx_de_emphasis:2;
>
> unsigned dis_metastability_quirk:1;
> + unsigned host_vbus_glitches:1;
>
> u16 imod_interval;
> };
> --
> 1.7.1
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