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Date: Fri, 19 Jan 2024 21:00:04 -0500
From: Frank Li <Frank.li@....com>
To: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Cc: "ran.wang_1@....com" <ran.wang_1@....com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"open list:DESIGNWARE USB3 DRD IP DRIVER" <linux-usb@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>,
"balbi@...nel.org" <balbi@...nel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"mark.rutland@....com" <mark.rutland@....com>,
"pku.leo@...il.com" <pku.leo@...il.com>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"sergei.shtylyov@...entembedded.com" <sergei.shtylyov@...entembedded.com>
Subject: Re: [PATCH 2/2] usb: dwc3: Add workaround for host mode VBUS glitch
when boot
On Sat, Jan 20, 2024 at 12:51:07AM +0000, Thinh Nguyen wrote:
> On Fri, Jan 19, 2024, Frank Li wrote:
> > From: Ran Wang <ran.wang_1@....com>
> >
> > 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>
> > Reviewed-by: Peter Chen <peter.chen@....com>
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> >
> > Notes:
> > Last review at June 06, 2019. Fixed all review comments and sent again.
> >
> > https://urldefense.com/v3/__https://lore.kernel.org/linux-kernel/AM5PR0402MB2865979E26017BC5937DBBA5F1170@AM5PR0402MB2865.eurprd04.prod.outlook.com/__;!!A4F2R9G_pg!bdutJWi1Tcz8SYscB7Mr96SWYMKIo8ElUKgEILFJfK3_60EbECQHXPBmJYAMMhNwQ4YrjxqMZWHdokXhHB6a$
> >
> > drivers/usb/dwc3/core.c | 2 ++
> > drivers/usb/dwc3/core.h | 2 ++
> > drivers/usb/dwc3/host.c | 46 +++++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 50 insertions(+)
> >
> > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > index 3e55838c00014..a57adf0c11dd1 100644
> > --- a/drivers/usb/dwc3/core.c
> > +++ b/drivers/usb/dwc3/core.c
> > @@ -1626,6 +1626,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
> > dwc->dis_split_quirk = device_property_read_bool(dev,
> > "snps,dis-split-quirk");
> >
> > + dwc->host_vbus_glitches = device_property_read_bool(dev, "snps,host-vbus-glitches");
>
> This is a quirk. The property should be named with "quirk" subfix.
> But do we need a new quirk? How many different platforms are affected?
> If it's just 1 or 2, then just use compatible string.
more than 2 platform. I think quirk is more flexible.
Frank
>
> > +
> > 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 e3eea965e57bf..0269bacbbf6bd 100644
> > --- a/drivers/usb/dwc3/core.h
> > +++ b/drivers/usb/dwc3/core.h
> > @@ -1135,6 +1135,7 @@ struct dwc3_scratchpad_array {
> > * @dis_split_quirk: set to disable split boundary.
> > * @wakeup_configured: set if the device is configured for remote wakeup.
> > * @suspended: set to track suspend event due to U3/L2.
> > + * @host_vbus_glitches: set to avoid vbus glitch during xhci reset.
>
> This is only applicable to the first xhci reset in its initialization
> and not every xhci reset right? If so, please reword.
>
> Also, please place it correspond to the order of the field.
>
> > * @imod_interval: set the interrupt moderation interval in 250ns
> > * increments or 0 to disable.
> > * @max_cfg_eps: current max number of IN eps used across all USB configs.
> > @@ -1353,6 +1354,7 @@ struct dwc3 {
> > unsigned tx_de_emphasis:2;
> >
> > unsigned dis_metastability_quirk:1;
> > + unsigned host_vbus_glitches:1;
> >
> > unsigned dis_split_quirk:1;
> > unsigned async_callbacks:1;
> > diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
> > index 61f57fe5bb783..af8903ee37c20 100644
> > --- a/drivers/usb/dwc3/host.c
> > +++ b/drivers/usb/dwc3/host.c
> > @@ -11,6 +11,7 @@
> > #include <linux/of.h>
> > #include <linux/platform_device.h>
> >
> > +#include "../host/xhci.h"
>
> Let's not import the entire xhci.h. If we're going to share some macros
> from xhci.h, please split them from xhci.h and perhaps create
> xhci-ports.h for dwc3 to share.
>
> > #include "core.h"
> >
> > static void dwc3_host_fill_xhci_irq_res(struct dwc3 *dwc,
> > @@ -28,6 +29,44 @@ static void dwc3_host_fill_xhci_irq_res(struct dwc3 *dwc,
> > dwc->xhci_resources[1].name = name;
> > }
> >
> > +#define XHCI_HCSPARAMS1 0x4
> > +#define XHCI_PORTSC_BASE 0x400
> > +
> > +/*
> > + * dwc3_power_off_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);
> > + 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");
> > +}
> > +
> > static int dwc3_host_get_irq(struct dwc3 *dwc)
> > {
> > struct platform_device *dwc3_pdev = to_platform_device(dwc->dev);
> > @@ -66,6 +105,13 @@ int dwc3_host_init(struct dwc3 *dwc)
> > int ret, irq;
> > int prop_idx = 0;
> >
> > + /*
> > + * 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)
> > + dwc3_power_off_all_roothub_ports(dwc);
> > +
>
> It's part of the dwc3_host_init(), but don't do this in
> dwc3_host_get_irq(). Place it where it makes sense.
>
> > irq = dwc3_host_get_irq(dwc);
> > if (irq < 0)
> > return irq;
> > --
> > 2.34.1
> >
>
> Please run checkpatch.pl and fix them next time. Regarding
> PARENTHESIS_ALIGNMENT or line continuation, it can be two indentations
> or parenthesis aligned, whichever one makes it easier to read.
>
>
> From checkpatch:
>
> CHECK:PARENTHESIS_ALIGNMENT: Alignment should match open parenthesis
> #119: FILE: drivers/usb/dwc3/host.c:48:
> + xhci_regs = ioremap(dwc->xhci_resources[0].start,
> + DWC3_XHCI_REGS_END);
>
> CHECK:SPACING: spaces preferred around that '*' (ctx:VxV)
> #130: FILE: drivers/usb/dwc3/host.c:59:
> + offset = op_regs_base + XHCI_PORTSC_BASE + 0x10*(i-1);
> ^
>
> CHECK:SPACING: spaces preferred around that '-' (ctx:VxV)
> #130: FILE: drivers/usb/dwc3/host.c:59:
> + offset = op_regs_base + XHCI_PORTSC_BASE + 0x10*(i-1);
> ^
>
> CHECK:BRACES: Unbalanced braces around else statement
> #137: FILE: drivers/usb/dwc3/host.c:66:
> + } else
>
Sorry, I too trust original patch author. Will fix next version
Frank
> total: 0 errors, 0 warnings, 4 checks, 86 lines checked
>
>
> Thanks,
> Thinh
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