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Message-ID: <20240123023916.jpakvznngiciwfwq@synopsys.com>
Date: Tue, 23 Jan 2024 02:39:26 +0000
From: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To: Frank Li <Frank.Li@....com>
CC: "mathias.nyman@...el.com" <mathias.nyman@...el.com>,
Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
"balbi@...nel.org" <balbi@...nel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"mark.rutland@....com" <mark.rutland@....com>,
"pku.leo@...il.com" <pku.leo@...il.com>,
"ran.wang_1@....com" <ran.wang_1@....com>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"sergei.shtylyov@...entembedded.com" <sergei.shtylyov@...entembedded.com>,
"imx@...ts.linux.dev" <imx@...ts.linux.dev>
Subject: Re: [PATCH v2 3/3] usb: dwc3: Add workaround for host mode VBUS
glitch when boot
On Sun, Jan 21, 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>
> ---
> drivers/usb/dwc3/core.c | 3 +++
> drivers/usb/dwc3/core.h | 2 ++
> drivers/usb/dwc3/host.c | 48 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 53 insertions(+)
>
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 3e55838c00014..3b68e8e45b8b9 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1626,6 +1626,9 @@ 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_quirk = device_property_read_bool(dev,
> + "snps,host-vbus-glitches-quirk");
> +
> 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..df544ec730d22 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1132,6 +1132,7 @@ struct dwc3_scratchpad_array {
> * 2 - No de-emphasis
> * 3 - Reserved
> * @dis_metastability_quirk: set to disable metastability quirk.
> + * @host_vbus_glitches_quirk: set to avoid vbus glitch during xhci reset.
> * @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.
> @@ -1353,6 +1354,7 @@ struct dwc3 {
> unsigned tx_de_emphasis:2;
>
> unsigned dis_metastability_quirk:1;
> + unsigned host_vbus_glitches_quirk: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..ee1ffe1500560 100644
> --- a/drivers/usb/dwc3/host.c
> +++ b/drivers/usb/dwc3/host.c
> @@ -11,6 +11,9 @@
> #include <linux/of.h>
> #include <linux/platform_device.h>
>
> +#include "../host/xhci-port.h"
> +#include "../host/xhci-ext-caps.h"
> +#include "../host/xhci-caps.h"
> #include "core.h"
>
> static void dwc3_host_fill_xhci_irq_res(struct dwc3 *dwc,
> @@ -28,6 +31,44 @@ 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;
Minor nit: please help keep the same style of declaring variables in
separate lines and reversed christmas tree.
> + 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");
> + }
> +}
> +
Minor nit: please move this hunk on top including the new define macros
instead of placing in the middle of irq related functions.
> static int dwc3_host_get_irq(struct dwc3 *dwc)
> {
> struct platform_device *dwc3_pdev = to_platform_device(dwc->dev);
> @@ -66,6 +107,13 @@ 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.
Reword "We have to ..." to "Some platforms need to ... "
> + */
> + if (dwc->host_vbus_glitches_quirk)
> + dwc3_power_off_all_roothub_ports(dwc);
> +
> irq = dwc3_host_get_irq(dwc);
> if (irq < 0)
> return irq;
> --
> 2.34.1
>
The rest looks fine to me.
Thanks,
Thinh
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