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Date: Tue, 25 Jan 2022 11:47:11 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Mathias Nyman <mathias.nyman@...ux.intel.com>
Cc: Greg KH <gregkh@...uxfoundation.org>,
Dave Hansen <dave.hansen@...el.com>,
Lu Baolu <baolu.lu@...ux.intel.com>, x86@...nel.org,
linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
Chunfeng Yun <chunfeng.yun@...iatek.com>
Subject: Re: earlyprintk=xdbc seems broken
On Tue, Jan 25, 2022 at 10:51:00AM +0200, Mathias Nyman wrote:
> On 24.1.2022 18.46, Peter Zijlstra wrote:
> > FYI, I'm thinking early_xdbc_parse_parameter should've now given
> > dpgp_num: 1 ?
> >
>
> Yes, it should.
>
> Looks like there's a parsing issue.
> "earlyprintk=xdbc1,keep" fails on our Tigerlake as well.
>
> Without the "keep" option it works for me:
>
> [ 0.000000] Command line: console=ttyS0,115200n8 buildroot_hostname=tgl04 earlyprintk=xdbc1 dmi_entry_point=0x74374000
> [ 0.000000] xhci_dbc:early_xdbc_parse_parameter: dbgp_num: 1
[ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-5.16.0+ root=UUID=a652986c-fbc6-4341-85c3-b4ad4402f130 ro debug ignore_loglevel sysrq_always_enabled usbcore.autosuspend=-1 earlyprintk=xdbc1,keep force_early_printk sched_verbose ft
race=nop mitigations=off nokaslr
[ 0.000000] xhci_dbc:early_xdbc_parse_parameter: dbgp_num: 1
[ 0.399988] xhci_dbc:xdbc_start: DbC is running now, control 0x8d000003 port ID 15
[ 0.399998] xhci_dbc:xdbc_handle_port_status: connect status change event
[ 0.399999] xhci_dbc:xdbc_handle_port_status: port reset change event
[ 0.431217] printk: console [earlyxdbc0] enabled
Success!! I'll go submit proper patches for this then.
---
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index d3c531d3b244..68b38925a74f 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -387,7 +387,7 @@ static int __init setup_early_printk(char *buf)
#endif
#ifdef CONFIG_EARLY_PRINTK_USB_XDBC
if (!strncmp(buf, "xdbc", 4))
- early_xdbc_parse_parameter(buf + 4);
+ early_xdbc_parse_parameter(buf + 4, keep);
#endif
buf++;
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index a698196377be..9bf3872895ab 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1505,6 +1505,7 @@ void __init tsc_early_init(void)
loops_per_jiffy = get_loops_per_jiffy();
tsc_enable_sched_clock();
+ use_tsc_delay();
}
void __init tsc_init(void)
diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 4502108069cd..a40db9618e8e 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -29,11 +29,15 @@
static struct xdbc_state xdbc;
static bool early_console_keep;
+#if 0
#ifdef XDBC_TRACE
#define xdbc_trace trace_printk
#else
static inline void xdbc_trace(const char *fmt, ...) { }
#endif /* XDBC_TRACE */
+#else
+#define xdbc_trace pr_err
+#endif
static void __iomem * __init xdbc_map_pci_mmio(u32 bus, u32 dev, u32 func)
{
@@ -417,9 +421,11 @@ static void xdbc_ring_doorbell(int target)
static int xdbc_start(void)
{
+ bool first_try = true;
u32 ctrl, status;
int ret;
+retry:
ctrl = readl(&xdbc.xdbc_reg->control);
writel(ctrl | CTRL_DBC_ENABLE | CTRL_PORT_ENABLE, &xdbc.xdbc_reg->control);
ret = handshake(&xdbc.xdbc_reg->control, CTRL_DBC_ENABLE, CTRL_DBC_ENABLE, 100000, 100);
@@ -429,13 +435,21 @@ static int xdbc_start(void)
}
/* Reset port to avoid bus hang: */
- if (xdbc.vendor == PCI_VENDOR_ID_INTEL)
+ if (xdbc.vendor == PCI_VENDOR_ID_INTEL && first_try)
xdbc_reset_debug_port();
/* Wait for port connection: */
ret = handshake(&xdbc.xdbc_reg->portsc, PORTSC_CONN_STATUS, PORTSC_CONN_STATUS, 5000000, 100);
if (ret) {
- xdbc_trace("waiting for connection timed out\n");
+ xdbc_trace("waiting for connection timed out, DCPORTSC:0x%x\n",
+ readl(&xdbc.xdbc_reg->portsc));
+ if (first_try) {
+ first_try = false;
+ /* Toggle DCE and retry without port reset */
+ writel(0, &xdbc.xdbc_reg->control);
+ handshake(&xdbc.xdbc_reg->control, CTRL_DBC_ENABLE, 0, 100000, 10);
+ goto retry;
+ }
return ret;
}
@@ -599,23 +631,26 @@ static int __init xdbc_early_setup(void)
return 0;
}
-int __init early_xdbc_parse_parameter(char *s)
+int __init early_xdbc_parse_parameter(char *s, int keep_early)
{
unsigned long dbgp_num = 0;
u32 bus, dev, func, offset;
+ char *e;
int ret;
if (!early_pci_allowed())
return -EPERM;
- if (strstr(s, "keep"))
- early_console_keep = true;
+ early_console_keep = keep_early;
if (xdbc.xdbc_reg)
return 0;
- if (*s && kstrtoul(s, 0, &dbgp_num))
- dbgp_num = 0;
+ if (*s) {
+ dbgp_num = simple_strtoul(s, &e, 10);
+ if (s == e)
+ dbgp_num = 0;
+ }
pr_notice("dbgp_num: %lu\n", dbgp_num);
diff --git a/include/linux/usb/xhci-dbgp.h b/include/linux/usb/xhci-dbgp.h
index 0a37f1283bf0..01fe768873f9 100644
--- a/include/linux/usb/xhci-dbgp.h
+++ b/include/linux/usb/xhci-dbgp.h
@@ -15,7 +15,7 @@
#define __LINUX_XHCI_DBGP_H
#ifdef CONFIG_EARLY_PRINTK_USB_XDBC
-int __init early_xdbc_parse_parameter(char *s);
+int __init early_xdbc_parse_parameter(char *s, int keep_early);
int __init early_xdbc_setup_hardware(void);
void __init early_xdbc_register_console(void);
#else
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