| Message ID | alpine.LRH.2.02.2005070853110.27409@file01.intranet.prod.int.rdu2.redhat.com |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | None | expand |
On Thu, May 07, 2020 at 08:57:09AM -0400, Mikulas Patocka wrote: > The patch 92d7223a74235054f2aa7227d207d9c57f84dca0 ("alpha: io: reorder > barriers to guarantee writeX() and iowriteX() ordering #2") broke boot on > the Alpha Avanti platform. > > The patch changes timing between accesses to the ISA bus, in particular, > it reduces the time between "write" access and a subsequent "read" access. > > This causes lock-up when accessing the real time clock and serial ports. > > This patch fixes the serial ports by adding a small delay before the "inb" > instruction. > > We introduce a global variable > alpha_has_broken_serial_ports_and_needs_delay - it is defined on Alpha and > it is set to 1 if we have the specific PCI-ISA bridge where this bug > occurs. We also introduce a new per-port flag UPQ_DELAY_BEFORE_READ, the > flag is set if alpha_has_broken_serial_ports_and_needs_delay is set and if > the serial port is an ISA port. > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > Fixes: 92d7223a7423 ("alpha: io: reorder barriers to guarantee writeX() and iowriteX() ordering #2") > Cc: stable@vger.kernel.org # v4.17+ > > --- > arch/alpha/include/asm/serial.h | 5 +++++ > arch/alpha/kernel/pci.c | 5 +++++ > drivers/tty/serial/8250/8250_core.c | 17 +++++++++++------ > drivers/tty/serial/8250/8250_port.c | 3 +++ > include/linux/serial_core.h | 1 + > 5 files changed, 25 insertions(+), 6 deletions(-) > > Index: linux-stable/arch/alpha/kernel/pci.c > =================================================================== > --- linux-stable.orig/arch/alpha/kernel/pci.c 2020-05-07 09:57:02.000000000 +0200 > +++ linux-stable/arch/alpha/kernel/pci.c 2020-05-07 14:30:07.000000000 +0200 > @@ -24,6 +24,7 @@ > #include <linux/slab.h> > #include <linux/syscalls.h> > #include <asm/machvec.h> > +#include <asm/serial.h> > > #include "proto.h" > #include "pci_impl.h" > @@ -61,9 +62,13 @@ struct pci_controller *pci_isa_hose; > * Quirks. > */ > > +int alpha_has_broken_serial_ports_and_needs_delay = 0; > +EXPORT_SYMBOL(alpha_has_broken_serial_ports_and_needs_delay); > + > static void quirk_isa_bridge(struct pci_dev *dev) > { > dev->class = PCI_CLASS_BRIDGE_ISA << 8; > + alpha_has_broken_serial_ports_and_needs_delay = 1; > } > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82378, quirk_isa_bridge); > > Index: linux-stable/drivers/tty/serial/8250/8250_port.c > =================================================================== > --- linux-stable.orig/drivers/tty/serial/8250/8250_port.c 2020-05-07 09:57:02.000000000 +0200 > +++ linux-stable/drivers/tty/serial/8250/8250_port.c 2020-05-07 09:57:02.000000000 +0200 > @@ -442,6 +442,9 @@ static unsigned int mem32be_serial_in(st > > static unsigned int io_serial_in(struct uart_port *p, int offset) > { > + if (unlikely(p->quirks & UPQ_DELAY_BEFORE_READ)) > + ndelay(300); > + > offset = offset << p->regshift; > return inb(p->iobase + offset); > } > Index: linux-stable/drivers/tty/serial/8250/8250_core.c > =================================================================== > --- linux-stable.orig/drivers/tty/serial/8250/8250_core.c 2020-05-07 09:57:02.000000000 +0200 > +++ linux-stable/drivers/tty/serial/8250/8250_core.c 2020-05-07 14:34:16.000000000 +0200 > @@ -487,9 +487,20 @@ static void univ8250_rsa_support(struct > #define univ8250_rsa_support(x) do { } while (0) > #endif /* CONFIG_SERIAL_8250_RSA */ > > +/* > + * This "device" covers _all_ ISA 8250-compatible serial devices listed > + * in the table in include/asm/serial.h > + */ > +static struct platform_device *serial8250_isa_devs; > + > static inline void serial8250_apply_quirks(struct uart_8250_port *up) > { > up->port.quirks |= skip_txen_test ? UPQ_NO_TXEN_TEST : 0; > +#ifdef alpha_has_broken_serial_ports_and_needs_delay That is a symbol, not a define, how does that work? greg k-h
On Thu, 7 May 2020, Greg Kroah-Hartman wrote: > On Thu, May 07, 2020 at 08:57:09AM -0400, Mikulas Patocka wrote: > > The patch 92d7223a74235054f2aa7227d207d9c57f84dca0 ("alpha: io: reorder > > barriers to guarantee writeX() and iowriteX() ordering #2") broke boot on > > the Alpha Avanti platform. > > > > The patch changes timing between accesses to the ISA bus, in particular, > > it reduces the time between "write" access and a subsequent "read" access. > > > > This causes lock-up when accessing the real time clock and serial ports. > > > > This patch fixes the serial ports by adding a small delay before the "inb" > > instruction. > > > > We introduce a global variable > > alpha_has_broken_serial_ports_and_needs_delay - it is defined on Alpha and > > it is set to 1 if we have the specific PCI-ISA bridge where this bug > > occurs. We also introduce a new per-port flag UPQ_DELAY_BEFORE_READ, the > > flag is set if alpha_has_broken_serial_ports_and_needs_delay is set and if > > the serial port is an ISA port. > > > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > > Fixes: 92d7223a7423 ("alpha: io: reorder barriers to guarantee writeX() and iowriteX() ordering #2") > > Cc: stable@vger.kernel.org # v4.17+ > > > > --- > > arch/alpha/include/asm/serial.h | 5 +++++ > > arch/alpha/kernel/pci.c | 5 +++++ > > drivers/tty/serial/8250/8250_core.c | 17 +++++++++++------ > > drivers/tty/serial/8250/8250_port.c | 3 +++ > > include/linux/serial_core.h | 1 + > > 5 files changed, 25 insertions(+), 6 deletions(-) > > > > Index: linux-stable/arch/alpha/kernel/pci.c > > =================================================================== > > --- linux-stable.orig/arch/alpha/kernel/pci.c 2020-05-07 09:57:02.000000000 +0200 > > +++ linux-stable/arch/alpha/kernel/pci.c 2020-05-07 14:30:07.000000000 +0200 > > @@ -24,6 +24,7 @@ > > #include <linux/slab.h> > > #include <linux/syscalls.h> > > #include <asm/machvec.h> > > +#include <asm/serial.h> > > > > #include "proto.h" > > #include "pci_impl.h" > > @@ -61,9 +62,13 @@ struct pci_controller *pci_isa_hose; > > * Quirks. > > */ > > > > +int alpha_has_broken_serial_ports_and_needs_delay = 0; > > +EXPORT_SYMBOL(alpha_has_broken_serial_ports_and_needs_delay); > > + > > static void quirk_isa_bridge(struct pci_dev *dev) > > { > > dev->class = PCI_CLASS_BRIDGE_ISA << 8; > > + alpha_has_broken_serial_ports_and_needs_delay = 1; > > } > > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82378, quirk_isa_bridge); > > > > Index: linux-stable/drivers/tty/serial/8250/8250_port.c > > =================================================================== > > --- linux-stable.orig/drivers/tty/serial/8250/8250_port.c 2020-05-07 09:57:02.000000000 +0200 > > +++ linux-stable/drivers/tty/serial/8250/8250_port.c 2020-05-07 09:57:02.000000000 +0200 > > @@ -442,6 +442,9 @@ static unsigned int mem32be_serial_in(st > > > > static unsigned int io_serial_in(struct uart_port *p, int offset) > > { > > + if (unlikely(p->quirks & UPQ_DELAY_BEFORE_READ)) > > + ndelay(300); > > + > > offset = offset << p->regshift; > > return inb(p->iobase + offset); > > } > > Index: linux-stable/drivers/tty/serial/8250/8250_core.c > > =================================================================== > > --- linux-stable.orig/drivers/tty/serial/8250/8250_core.c 2020-05-07 09:57:02.000000000 +0200 > > +++ linux-stable/drivers/tty/serial/8250/8250_core.c 2020-05-07 14:34:16.000000000 +0200 > > @@ -487,9 +487,20 @@ static void univ8250_rsa_support(struct > > #define univ8250_rsa_support(x) do { } while (0) > > #endif /* CONFIG_SERIAL_8250_RSA */ > > > > +/* > > + * This "device" covers _all_ ISA 8250-compatible serial devices listed > > + * in the table in include/asm/serial.h > > + */ > > +static struct platform_device *serial8250_isa_devs; > > + > > static inline void serial8250_apply_quirks(struct uart_8250_port *up) > > { > > up->port.quirks |= skip_txen_test ? UPQ_NO_TXEN_TEST : 0; > > +#ifdef alpha_has_broken_serial_ports_and_needs_delay > > That is a symbol, not a define, how does that work? > > greg k-h That's both the symbol and a define - see this part of the patch: Mikulas Index: linux-stable/arch/alpha/include/asm/serial.h =================================================================== --- linux-stable.orig/arch/alpha/include/asm/serial.h 2020-02-07 11:52:16.000000000 +0100 +++ linux-stable/arch/alpha/include/asm/serial.h 2020-05-07 14:48:21.000000000 +0200 @@ -28,3 +28,8 @@ { 0, BASE_BAUD, 0x2F8, 3, STD_COM_FLAGS }, /* ttyS1 */ \ { 0, BASE_BAUD, 0x3E8, 4, STD_COM_FLAGS }, /* ttyS2 */ \ { 0, BASE_BAUD, 0x2E8, 3, STD_COM4_FLAGS }, /* ttyS3 */ + +#ifdef CONFIG_PCI +extern int alpha_has_broken_serial_ports_and_needs_delay; +#define alpha_has_broken_serial_ports_and_needs_delay alpha_has_broken_serial_ports_and_needs_delay +#endif
Index: linux-stable/arch/alpha/kernel/pci.c =================================================================== --- linux-stable.orig/arch/alpha/kernel/pci.c 2020-05-07 09:57:02.000000000 +0200 +++ linux-stable/arch/alpha/kernel/pci.c 2020-05-07 14:30:07.000000000 +0200 @@ -24,6 +24,7 @@ #include <linux/slab.h> #include <linux/syscalls.h> #include <asm/machvec.h> +#include <asm/serial.h> #include "proto.h" #include "pci_impl.h" @@ -61,9 +62,13 @@ struct pci_controller *pci_isa_hose; * Quirks. */ +int alpha_has_broken_serial_ports_and_needs_delay = 0; +EXPORT_SYMBOL(alpha_has_broken_serial_ports_and_needs_delay); + static void quirk_isa_bridge(struct pci_dev *dev) { dev->class = PCI_CLASS_BRIDGE_ISA << 8; + alpha_has_broken_serial_ports_and_needs_delay = 1; } DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82378, quirk_isa_bridge); Index: linux-stable/drivers/tty/serial/8250/8250_port.c =================================================================== --- linux-stable.orig/drivers/tty/serial/8250/8250_port.c 2020-05-07 09:57:02.000000000 +0200 +++ linux-stable/drivers/tty/serial/8250/8250_port.c 2020-05-07 09:57:02.000000000 +0200 @@ -442,6 +442,9 @@ static unsigned int mem32be_serial_in(st static unsigned int io_serial_in(struct uart_port *p, int offset) { + if (unlikely(p->quirks & UPQ_DELAY_BEFORE_READ)) + ndelay(300); + offset = offset << p->regshift; return inb(p->iobase + offset); } Index: linux-stable/drivers/tty/serial/8250/8250_core.c =================================================================== --- linux-stable.orig/drivers/tty/serial/8250/8250_core.c 2020-05-07 09:57:02.000000000 +0200 +++ linux-stable/drivers/tty/serial/8250/8250_core.c 2020-05-07 14:34:16.000000000 +0200 @@ -487,9 +487,20 @@ static void univ8250_rsa_support(struct #define univ8250_rsa_support(x) do { } while (0) #endif /* CONFIG_SERIAL_8250_RSA */ +/* + * This "device" covers _all_ ISA 8250-compatible serial devices listed + * in the table in include/asm/serial.h + */ +static struct platform_device *serial8250_isa_devs; + static inline void serial8250_apply_quirks(struct uart_8250_port *up) { up->port.quirks |= skip_txen_test ? UPQ_NO_TXEN_TEST : 0; +#ifdef alpha_has_broken_serial_ports_and_needs_delay + if (alpha_has_broken_serial_ports_and_needs_delay && + serial8250_isa_devs && up->port.dev == &serial8250_isa_devs->dev) + up->port.quirks |= UPQ_DELAY_BEFORE_READ; +#endif } static void __init serial8250_isa_init_ports(void) @@ -903,12 +914,6 @@ static struct platform_driver serial8250 }; /* - * This "device" covers _all_ ISA 8250-compatible serial devices listed - * in the table in include/asm/serial.h - */ -static struct platform_device *serial8250_isa_devs; - -/* * serial8250_register_8250_port and serial8250_unregister_port allows for * 16x50 serial ports to be configured at run-time, to support PCMCIA * modems and PCI multiport cards. Index: linux-stable/include/linux/serial_core.h =================================================================== --- linux-stable.orig/include/linux/serial_core.h 2020-05-07 09:57:02.000000000 +0200 +++ linux-stable/include/linux/serial_core.h 2020-05-07 09:57:02.000000000 +0200 @@ -154,6 +154,7 @@ struct uart_port { /* quirks must be updated while holding port mutex */ #define UPQ_NO_TXEN_TEST BIT(0) +#define UPQ_DELAY_BEFORE_READ BIT(1) unsigned int read_status_mask; /* driver specific */ unsigned int ignore_status_mask; /* driver specific */ Index: linux-stable/arch/alpha/include/asm/serial.h =================================================================== --- linux-stable.orig/arch/alpha/include/asm/serial.h 2020-02-07 11:52:16.000000000 +0100 +++ linux-stable/arch/alpha/include/asm/serial.h 2020-05-07 14:48:21.000000000 +0200 @@ -28,3 +28,8 @@ { 0, BASE_BAUD, 0x2F8, 3, STD_COM_FLAGS }, /* ttyS1 */ \ { 0, BASE_BAUD, 0x3E8, 4, STD_COM_FLAGS }, /* ttyS2 */ \ { 0, BASE_BAUD, 0x2E8, 3, STD_COM4_FLAGS }, /* ttyS3 */ + +#ifdef CONFIG_PCI +extern int alpha_has_broken_serial_ports_and_needs_delay; +#define alpha_has_broken_serial_ports_and_needs_delay alpha_has_broken_serial_ports_and_needs_delay +#endif
The patch 92d7223a74235054f2aa7227d207d9c57f84dca0 ("alpha: io: reorder barriers to guarantee writeX() and iowriteX() ordering #2") broke boot on the Alpha Avanti platform. The patch changes timing between accesses to the ISA bus, in particular, it reduces the time between "write" access and a subsequent "read" access. This causes lock-up when accessing the real time clock and serial ports. This patch fixes the serial ports by adding a small delay before the "inb" instruction. We introduce a global variable alpha_has_broken_serial_ports_and_needs_delay - it is defined on Alpha and it is set to 1 if we have the specific PCI-ISA bridge where this bug occurs. We also introduce a new per-port flag UPQ_DELAY_BEFORE_READ, the flag is set if alpha_has_broken_serial_ports_and_needs_delay is set and if the serial port is an ISA port. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Fixes: 92d7223a7423 ("alpha: io: reorder barriers to guarantee writeX() and iowriteX() ordering #2") Cc: stable@vger.kernel.org # v4.17+ --- arch/alpha/include/asm/serial.h | 5 +++++ arch/alpha/kernel/pci.c | 5 +++++ drivers/tty/serial/8250/8250_core.c | 17 +++++++++++------ drivers/tty/serial/8250/8250_port.c | 3 +++ include/linux/serial_core.h | 1 + 5 files changed, 25 insertions(+), 6 deletions(-)