Re: Touchpad stickiness on AMD laptops (was Dell Inspiron/XPS)

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+ Nehal from the AMD platform drivers team

On 1/11/2022 05:13, Benjamin Tissoires wrote:
On Tue, Jan 11, 2022 at 11:34 AM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:

Hi Wolfram,

On 1/6/22 14:14, Wolfram Sang wrote:
Hi Hans,

bumping this old thread because there might be some progress and it
still affects quite some people.

But I must be honest here, I don't see much progress being made
on this until someone with a significant amount of kernel / hw-enablement
experience gets it hands on one of these models. Either because some

So, I am quite optimistic that Andrea's issue is the same one which
Miroslav Bendik dived into [1]. I will surely try to help with part of
the PIIX I2C driver, but I lack the experience with the RMI4 driver. I
wonder if you could have a look and maybe share your thoughts?

Thanks and all the best,

    Wolfram

[1] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fr%2FCAPoEpV0ZSidL6aMXvB6LN1uS-3CUHS4ggT8RwFgmkzzCiYJ-XQ%40mail.gmail.com&amp;data=04%7C01%7Cmario.limonciello%40amd.com%7Cc0a66169619743575d0008d9d4f36227%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637774964813744208%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=2PEWQqq%2FqAl3WkxoaKYP5bqpeYoUqvgXwLxHtI5rEOQ%3D&amp;reserved=0

Benjamin Tissoires really is the export on the synaptics PS/2 -> switch to
smbus mode devices, he did all the initial hw-enablement for them.

Benjamin, see the email Wolfram linked above. It seems that on AMD
laptops we have synaptics intertouch devices connected to a plain
PIIX4 compatible I2C controller.

Oh, nice (looking at the thread). IIRC last time somebody tried to
communicate with those touchpads it wasn't working at all.


So we need to either add support for SMBUS host-notify to the
PIIX4 smbus driver (at least for AMD parts) or we need to support
OOB IRQ signalling in the rmi4 code, assuming there is an OOB IRQ
at all.

If the touchpad is using SMBus, we need to have Host Notify. Google
gave me the following datasheet for PIIX4
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.intel.com%2FAssets%2FPDF%2Fdatasheet%2F290562.pdf&amp;data=04%7C01%7Cmario.limonciello%40amd.com%7Cc0a66169619743575d0008d9d4f36227%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637774964813744208%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=SkwEfI9PxDidXisredOxjP11u%2FGwdq9UTwqqp4EOTZY%3D&amp;reserved=0 and it seems we
would need to enable something in the section 7.3.9.

Nehal - can your team please look into the lack of I2C_FUNC_SMBUS_HOST_NOTIFY? This causes SMBus touchpads to be unable to function out of PS/2 mode.

You can find many more details in the analysis that Miroslav did on what's missing in this thread:

https://lore.kernel.org/all/5fc2c68d-a9df-402a-58b5-fdd531f86b55@xxxxxxxxx/


However, without the hardware it's going to be tough for me to enable :/

For regular I2C touchpads, there is an OOB IRQ we can set up, but when
the devices are presented and enabled through PS/2 first, they are
using SMBus only AFAICT.

Cheers,
Benjamin


I've also added Mario Limonciello from AMD's client group to the Cc,

Mario, we can really use some help / insight from AMD here, both with
the problem to detect the IO addresses of the AMD PIIX4 compatible
smbus controller as well as with smbus host-notify support, see:

https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fr%2FCAPoEpV0ZSidL6aMXvB6LN1uS-3CUHS4ggT8RwFgmkzzCiYJ-XQ%40mail.gmail.com&amp;data=04%7C01%7Cmario.limonciello%40amd.com%7Cc0a66169619743575d0008d9d4f36227%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637774964813744208%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=2PEWQqq%2FqAl3WkxoaKYP5bqpeYoUqvgXwLxHtI5rEOQ%3D&amp;reserved=0

Regards,

Hans



Hans,

This thread has splintered but it comes down to two pieces to this puzzle:

1) Systems returning SMBUS address 0xff

The address can be potentially be returned using port I/O or it can be done using MMIO.

There is already a thread in process to add support for MMIO, but last I heard it's waiting for review comments.

https://lore.kernel.org/all/20210715221828.244536-1-Terry.Bowman@xxxxxxx/

Besides receiving a review and modifying for review comments that patch has to spin at least one more time to extend AMD_PCI_SMBUS_REVISION_MMIO to 0x51 or later instead of 0x59 or later.

2) SMBus host notify (support for handling interrupts from slave device).

I've looped in the lead from the platform drivers team Nehal to comment
on adding this feature.

Now something else interesting - the SMBUS controller in these laptops often is listed in the ACPI tables on IRQ7 with a _HID of SMB0001.

That is adding an ISR for SMBUS Host Notify support may also potentially mean needing to revert 2bbb5fa37475d7aa5fa62f34db1623f3da2dfdfa

And maybe if we're lucky https://bugzilla.kernel.org/show_bug.cgi?id=201817 gets fixed too.



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