On 10. 10. 2024 18:25, Mario Limonciello wrote:
On 2/12/2022 11:42, Miroslav Bendík wrote:
Hello,
i think, that SMBus works now pretty good and last problem is
screaming interrupt from synaptics (1000 irq/s). I need little help
to solve this problem.
Little summary first:
On this thinkpad is synaptics trackpoint/touchpad connected to PIIX4.
To enable RMI4 mode, SMBus driver should support host notify
protocol. I have added support of host notify and replaced active
waiting transaction with completer + interrupt. Driver is now pretty
stable and works way better, than old implementation. For example
i2c-detect shows real devices (previous transaction code showed all
addresses from 0x1c as active). Patch on following link is still
hack, has hardcoded IRQ and supports host notifications and
interrupts only on auxiliary port. I can implement other ports later.
Patch: https://lore.kernel.org/all/c9b0b147-2907-
ff41-4f13-464b3b891c50@xxxxxxxxxxxxx/
This patch includes PM register access using MMIO: https://
lore.kernel.org/all/20210715221828.244536-1-Terry.Bowman@xxxxxxx/
Now i can load psmouse synaptics_intertouch=1 and everything works
great, but it uses 5% CPU and interrupt is called 1000/s. I have
changed interrupt from rising edge to active low (it's PCIE, PCIE has
active low) and i have many times checked if all interrupt bits are
cleared in interrupt request. Yes, they are always cleared.
Interrupts are generated only after first touch if i have compiled
only F12. If i compile F03, then interrupts are generated immediately
after load of psmouse. After unload, interrupts are not generated
(i2c-piix4 still loaded).
On this machine I2C is accessible using GPIO 19(SCL), 20(SDA). Using
kernel thread with RT priority on isolated core i have tried to
record pin values on GPIO pins. Latency is too high to record all
transferred data. Some state changes are lost (approximately 1/50
bits). Not too low to read reliably all data, but good enough to see
what happens at bus level. Here is recorded file:
https://mireq.linuxos.sk/kernel/ thinkpad_p14s/i2c_scl_sda.xz.
Every byte is sample, first bit is SCL, second SDA. Sample rate is
cca 500 000 Hz, but often drops under 100 000 (lost bit).
On this screenshot is typical activity on bus:
https://mireq.linuxos.sk/ kernel/thinkpad_p14s/i2c_1.png (pulseview
with imported raw file)
Zoom to two packet is here: https://mireq.linuxos.sk/kernel/
thinkpad_p14s/i2c_2.png
First packet is SMBus host notify. Address 0x08 is SMBus host address
and 0x58 is address of synaptics (0x2c << 1). Second packet is
reading of interrupt status registers. Data 02 is length of interrupt
status register (9 bits) and last 2 bytes are zero (idle, when moving
cursor, then interrupt status register contains one bit set).
Zoomed out: https://mireq.linuxos.sk/kernel/thinkpad_p14s/i2c_3.png
Before transaction SMBus slave state machine is disabled and after
transaction enabled. If notification is received when state machine
is disabled, then device writes only address and don't get response.
If driver runs with always enabled slave state machine, then output
will contain only notify + read interrupt status pairs and no
separate addresses, but with this mode bus collisions occur more often.
Here is dmesg output: https://pastebin.com/RdDYHJn0
Cursor is moved until 2862.8, then i have not touched trackpoint.
Idle device don't produce bus collisions. Moving cursor produces
collisions, but sample rate is stable 100Hz, which is way better,
than <40 Hz with PS/2 mode. I don't know how to solve collisions.
Maybe they are related to not silenced host notifications.
If i were to be optimistic, then i would say that clearing interrupt
vector will solve all problems. According old RMI4 documentation,
reading from interrupt status register should clear interrupts
(status register is cleared), but this don't prevent device form
sending host notifications. Maybe exists new way to disable
interrupts. I don't know, i have no access to current documentation.
My device has this signature:
Synaptics, product: TM3471-030, fw id: 3418235
Any help welcome.
Sorry to bump such an old thread, but AFAIK you never came up with a
good solution here. I did want to point out that there was a very
recent submission by Shyam (CC'ed) [1] that adds an ASF driver (which
is an extension to PIIX4). By default it's going to bind to an ACPI
ID that isn't present on your system (present on newer systems only)
but the hardware for ASF /should/ be present even on yours.
So I was going to suggest if you still are interested in this to play
with that series and come up with a way to force using ASF (perhaps by
a DMI match for your system) and see how that goes.
[1]
https://lore.kernel.org/all/20240923080401.2167310-1-Shyam-sundar.S-k@xxxxxxx/
Hello.
Thanks for the update. It looks good as a separate driver. I had
intended to split this driver, replace polling with interrupts, and
convert all I/O calls to MMIO, similar to how a Windows driver operates.
I paused the work because I needed documentation and fixes from other
companies, and I resolved my issue using a different approach:
- I have not received a response from Synaptics.
- I have not received a response from Lenovo.
- I have fixed the original issue -
https://patchwork.kernel.org/project/linux-input/patch/71d9dc66-9576-c26f-c9d9-129217f50255@xxxxxxxxx/#24848525
- Too many subsystems are affected, some of which are currently hardly
fixable.
The biggest issue is interrupt support, which cannot be resolved with
quirks alone.
My device has this DSDT ACPI entry:
Name (_HID, "SMB0001") // _HID: Hardware ID
Name (_CRS, ResourceTemplate () // _CRS: Current Resource Settings
{
IO (Decode16,
0x0B20, // Range Minimum
0x0B20, // Range Maximum
0x20, // Alignment
0x20, // Length
)
IRQ (Level, ActiveLow, Shared, )
{7}
})
This entry defines the IRQ number, trigger, and polarity. However, the
kernel ignores this entry and only uses the "Interrupt Source Override"
from the MADT table. Here are some potential solutions:
- Scan ACPI for interrupts and include them in overrides
- Scanning might break or fix many drivers. This is a significant
change that could affect numerous buggy BIOS ACPI implementations.
- Change the interrupt trigger and polarity on the fly in the ASF driver
- The interrupt trigger cannot be changed with irq_set_type because
it lacks an ioapic_ir_chip.irq_set_type implementation
- Implement a new quirk or hook to modify interrupts
- This would involve extending the quirk system to allow changes to
polarity/trigger before APIC initialization.
- Add the missing MADT table
- Lenovo ignores this requirement.
Fixing this bug might break trackpoint support on ThinkPads, as the
Synaptics firmware does not behave as described in the documentation.
Given the high potential for system instability with minimal gain, my
requested feature may not be worth pursuing.
I can maybe help with testing this new ASF driver on older hardware
without specific ACPI ID.
