Re: [PATCH] ACPI / scan: Fix regression related to X-Gene UARTs
On Sun, 2018-04-22 at 11:34 +0200, Rafael J. Wysocki wrote: > On Fri, Apr 20, 2018 at 5:29 AM, Mark Salterwrote: > > Commit e361d1f85855 ("ACPI / scan: Fix enumeration for special UART > > devices") caused a regression with some X-Gene based platforms (Mustang > > and M400) with invalid DSDT. > > I'm not convinced that making changes to the core ACPI device > enumeration code in order to cover up for firmware bugs is the right > approach. It is unfortunate but the firmware bug predates the change which uncovered it, so previously working systems no longer work. > > > The DSDT makes it appear that the UART > > device is also a slave device attached to itself. With the above commit > > the UART won't be enumerated by ACPI scan (slave serial devices shouldn't > > be). So check for X-Gene UART device and skip slace device check on it. > > > > Signed-off-by: Mark Salter > > --- > > drivers/acpi/scan.c | 8 > > 1 file changed, 8 insertions(+) > > > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > > index cc234e6a6297..1dcdd0122862 100644 > > --- a/drivers/acpi/scan.c > > +++ b/drivers/acpi/scan.c > > @@ -1551,6 +1551,14 @@ static bool acpi_device_enumeration_by_parent(struct > > acpi_device *device) > > fwnode_property_present(>fwnode, "baud"))) > > return true; > > > > + /* > > +* Firmware on some arm64 X-Gene platforms will make the UART > > +* device appear as both a UART and a slave of that UART. Just > > +* bail out here for X-Gene UARTs. > > +*/ > > + if (!strcmp(acpi_device_hid(device), "APMC0D08")) > > + return false; > > Is the device ID never to be used outside of the broken configurations? > > Even if that's the plan, how are you going to guarantee that anyway? The device ID will always be used for X-Gene UARTs. Whether the DSDT is broken or not wouldn't matter because the end result would be the same (the UART being treated as master rather than a serial bus slave). The broken firmware looks like this: Device (URT0) { Name (_HID, "APMC0D08") // _HID: Hardware ID ... Name (_CRS, ResourceTemplate () // _CRS: Current Resource Settings { Memory32Fixed (ReadWrite, 0x1C02, // Address Base 0x0100, // Address Length ) UartSerialBusV2 (0x0001C200, DataBitsEight, StopBitsOne, 0x00, LittleEndian, ParityTypeNone, FlowControlNone, 0x0010, 0x0010, "URT0", 0x00, ResourceConsumer, , Exclusive, ) Interrupt (ResourceConsumer, Level, ActiveHigh, Exclusive, ,, ) { 0x006D, } }) ... } So "URT0" has a UartSerialBusV2 resource which references itself as the bus master. > > > + > > INIT_LIST_HEAD(_list); > > acpi_dev_get_resources(device, _list, > >acpi_check_serial_bus_slave, > > --
Re: [PATCH] ACPI / scan: Fix regression related to X-Gene UARTs
On Sun, 2018-04-22 at 11:34 +0200, Rafael J. Wysocki wrote: > On Fri, Apr 20, 2018 at 5:29 AM, Mark Salter wrote: > > Commit e361d1f85855 ("ACPI / scan: Fix enumeration for special UART > > devices") caused a regression with some X-Gene based platforms (Mustang > > and M400) with invalid DSDT. > > I'm not convinced that making changes to the core ACPI device > enumeration code in order to cover up for firmware bugs is the right > approach. It is unfortunate but the firmware bug predates the change which uncovered it, so previously working systems no longer work. > > > The DSDT makes it appear that the UART > > device is also a slave device attached to itself. With the above commit > > the UART won't be enumerated by ACPI scan (slave serial devices shouldn't > > be). So check for X-Gene UART device and skip slace device check on it. > > > > Signed-off-by: Mark Salter > > --- > > drivers/acpi/scan.c | 8 > > 1 file changed, 8 insertions(+) > > > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > > index cc234e6a6297..1dcdd0122862 100644 > > --- a/drivers/acpi/scan.c > > +++ b/drivers/acpi/scan.c > > @@ -1551,6 +1551,14 @@ static bool acpi_device_enumeration_by_parent(struct > > acpi_device *device) > > fwnode_property_present(>fwnode, "baud"))) > > return true; > > > > + /* > > +* Firmware on some arm64 X-Gene platforms will make the UART > > +* device appear as both a UART and a slave of that UART. Just > > +* bail out here for X-Gene UARTs. > > +*/ > > + if (!strcmp(acpi_device_hid(device), "APMC0D08")) > > + return false; > > Is the device ID never to be used outside of the broken configurations? > > Even if that's the plan, how are you going to guarantee that anyway? The device ID will always be used for X-Gene UARTs. Whether the DSDT is broken or not wouldn't matter because the end result would be the same (the UART being treated as master rather than a serial bus slave). The broken firmware looks like this: Device (URT0) { Name (_HID, "APMC0D08") // _HID: Hardware ID ... Name (_CRS, ResourceTemplate () // _CRS: Current Resource Settings { Memory32Fixed (ReadWrite, 0x1C02, // Address Base 0x0100, // Address Length ) UartSerialBusV2 (0x0001C200, DataBitsEight, StopBitsOne, 0x00, LittleEndian, ParityTypeNone, FlowControlNone, 0x0010, 0x0010, "URT0", 0x00, ResourceConsumer, , Exclusive, ) Interrupt (ResourceConsumer, Level, ActiveHigh, Exclusive, ,, ) { 0x006D, } }) ... } So "URT0" has a UartSerialBusV2 resource which references itself as the bus master. > > > + > > INIT_LIST_HEAD(_list); > > acpi_dev_get_resources(device, _list, > >acpi_check_serial_bus_slave, > > --
Re: [PATCH] ACPI / scan: Fix regression related to X-Gene UARTs
On Fri, Apr 20, 2018 at 5:29 AM, Mark Salterwrote: > Commit e361d1f85855 ("ACPI / scan: Fix enumeration for special UART > devices") caused a regression with some X-Gene based platforms (Mustang > and M400) with invalid DSDT. I'm not convinced that making changes to the core ACPI device enumeration code in order to cover up for firmware bugs is the right approach. > The DSDT makes it appear that the UART > device is also a slave device attached to itself. With the above commit > the UART won't be enumerated by ACPI scan (slave serial devices shouldn't > be). So check for X-Gene UART device and skip slace device check on it. > > Signed-off-by: Mark Salter > --- > drivers/acpi/scan.c | 8 > 1 file changed, 8 insertions(+) > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index cc234e6a6297..1dcdd0122862 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -1551,6 +1551,14 @@ static bool acpi_device_enumeration_by_parent(struct > acpi_device *device) > fwnode_property_present(>fwnode, "baud"))) > return true; > > + /* > +* Firmware on some arm64 X-Gene platforms will make the UART > +* device appear as both a UART and a slave of that UART. Just > +* bail out here for X-Gene UARTs. > +*/ > + if (!strcmp(acpi_device_hid(device), "APMC0D08")) > + return false; Is the device ID never to be used outside of the broken configurations? Even if that's the plan, how are you going to guarantee that anyway? > + > INIT_LIST_HEAD(_list); > acpi_dev_get_resources(device, _list, >acpi_check_serial_bus_slave, > --
Re: [PATCH] ACPI / scan: Fix regression related to X-Gene UARTs
On Fri, Apr 20, 2018 at 5:29 AM, Mark Salter wrote: > Commit e361d1f85855 ("ACPI / scan: Fix enumeration for special UART > devices") caused a regression with some X-Gene based platforms (Mustang > and M400) with invalid DSDT. I'm not convinced that making changes to the core ACPI device enumeration code in order to cover up for firmware bugs is the right approach. > The DSDT makes it appear that the UART > device is also a slave device attached to itself. With the above commit > the UART won't be enumerated by ACPI scan (slave serial devices shouldn't > be). So check for X-Gene UART device and skip slace device check on it. > > Signed-off-by: Mark Salter > --- > drivers/acpi/scan.c | 8 > 1 file changed, 8 insertions(+) > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index cc234e6a6297..1dcdd0122862 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -1551,6 +1551,14 @@ static bool acpi_device_enumeration_by_parent(struct > acpi_device *device) > fwnode_property_present(>fwnode, "baud"))) > return true; > > + /* > +* Firmware on some arm64 X-Gene platforms will make the UART > +* device appear as both a UART and a slave of that UART. Just > +* bail out here for X-Gene UARTs. > +*/ > + if (!strcmp(acpi_device_hid(device), "APMC0D08")) > + return false; Is the device ID never to be used outside of the broken configurations? Even if that's the plan, how are you going to guarantee that anyway? > + > INIT_LIST_HEAD(_list); > acpi_dev_get_resources(device, _list, >acpi_check_serial_bus_slave, > --
[PATCH] ACPI / scan: Fix regression related to X-Gene UARTs
Commit e361d1f85855 ("ACPI / scan: Fix enumeration for special UART devices") caused a regression with some X-Gene based platforms (Mustang and M400) with invalid DSDT. The DSDT makes it appear that the UART device is also a slave device attached to itself. With the above commit the UART won't be enumerated by ACPI scan (slave serial devices shouldn't be). So check for X-Gene UART device and skip slace device check on it. Signed-off-by: Mark Salter--- drivers/acpi/scan.c | 8 1 file changed, 8 insertions(+) diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index cc234e6a6297..1dcdd0122862 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -1551,6 +1551,14 @@ static bool acpi_device_enumeration_by_parent(struct acpi_device *device) fwnode_property_present(>fwnode, "baud"))) return true; + /* +* Firmware on some arm64 X-Gene platforms will make the UART +* device appear as both a UART and a slave of that UART. Just +* bail out here for X-Gene UARTs. +*/ + if (!strcmp(acpi_device_hid(device), "APMC0D08")) + return false; + INIT_LIST_HEAD(_list); acpi_dev_get_resources(device, _list, acpi_check_serial_bus_slave, -- 2.14.3
[PATCH] ACPI / scan: Fix regression related to X-Gene UARTs
Commit e361d1f85855 ("ACPI / scan: Fix enumeration for special UART devices") caused a regression with some X-Gene based platforms (Mustang and M400) with invalid DSDT. The DSDT makes it appear that the UART device is also a slave device attached to itself. With the above commit the UART won't be enumerated by ACPI scan (slave serial devices shouldn't be). So check for X-Gene UART device and skip slace device check on it. Signed-off-by: Mark Salter --- drivers/acpi/scan.c | 8 1 file changed, 8 insertions(+) diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index cc234e6a6297..1dcdd0122862 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -1551,6 +1551,14 @@ static bool acpi_device_enumeration_by_parent(struct acpi_device *device) fwnode_property_present(>fwnode, "baud"))) return true; + /* +* Firmware on some arm64 X-Gene platforms will make the UART +* device appear as both a UART and a slave of that UART. Just +* bail out here for X-Gene UARTs. +*/ + if (!strcmp(acpi_device_hid(device), "APMC0D08")) + return false; + INIT_LIST_HEAD(_list); acpi_dev_get_resources(device, _list, acpi_check_serial_bus_slave, -- 2.14.3