https://bugzilla.kernel.org/show_bug.cgi?id=213353
Bug ID: 213353
Summary: IRQs for onboard UARTs are not level-triggered with
IRQNoFlags even if the parent section has the defaults
in PRS
Product: ACPI
Version: 2.5
Kernel Version: 5.12.8
Hardware: All
OS: Linux
Tree: Mainline
Status: NEW
Severity: enhancement
Priority: P1
Component: Config-Interrupts
Assignee: [email protected]
Reporter: [email protected]
Regression: No
I have tablet with that supposedly has a serial-attached EETI touchscreen
device.
# dmesg | grep ttyS0
[ 3.896102] 00:01: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a
16550A
When trying to use it via inputattach, it fails:
# inputattach -eeti /dev/ttyS0
inputattach: device initialization failed
The IRQ set up for the UART is edge-triggered, while it's attached to the LPC
bus and should be level-trigered:
# grep " 4:" /proc/interrupts
4: 0 1 0 0 IO-APIC 4-edge
Disassembling the DSDT, I can see this:
Scope (_SB)
{
...
/* IRQ defaults for (E)ISA/LPC IRQs? */
Name (PRSA, ResourceTemplate ()
{
IRQ (Level, ActiveLow, Shared, )
{3,4,5,6,10,11,12,14,15}
})
Alias (PRSA, PRSB)
Alias (PRSA, PRSC)
Alias (PRSA, PRSD)
Alias (PRSA, PRSE)
Alias (PRSA, PRSF)
Alias (PRSA, PRSG)
Alias (PRSA, PRSH)
The serial device is in the above parent scope:
Device (IURT)
{
Name (_HID, EisaId ("PNP0501") /* 16550A-compatible COM
Serial Port */) // _HID: Hardware ID
Name (_UID, One) // _UID: Unique ID
Method (_STA, 0, Serialized) // _STA: Status
{
If ((USEL == Zero))
{
UI4E = One
C1EN = One
Return (0x0F)
}
Return (Zero)
}
Method (_DIS, 0, Serialized) // _DIS: Disable Device
{
If (((BDID != One) && ((BDID != 0x0A) &&
(BDID != 0x09))))
{
UI4E = Zero
C1EN = Zero
}
}
Method (_CRS, 0, Serialized) // _CRS: Current Resource
Settings
{
Name (BUF0, ResourceTemplate ()
{
IO (Decode16,
0x03F8, // Range Minimum
0x03F8, // Range Maximum
0x01, // Alignment
0x08, // Length
)
IRQNoFlags ()
{4}
})
Return (BUF0) /* \_SB_.PCI0.LPCB.IURT._CRS.BUF0 */
}
}
It seems to me that the IRQ default parameters from PRS are not applied to the
PNP0501 device and as such, the serial device doesn't work.
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