Re: elan_i2c: failed to read report data: -71

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Uwe,

On Tue, Mar 02, 2021 at 10:09:34PM +0100, Uwe Kleine-König wrote:
> Hello,
> 
> I just installed Linux on a new Thinkpad E15 and I experience a
> non-working touchpad. I can move the mouse just fine, but when I press
> one of the three buttons or move the trackpoint the kernel log gets
> flooded with:
> 
> 	elan_i2c 0-0015: failed to read report data: -71
> 
> and nothing happens in the GUI.
> 
> This is a kernel from Debian testing, i.e. 5.10.13, during probe of the
> device the following is reported:
> 
> 	elan_i2c 0-0015: supply vcc not found, using dummy regulator
> 	elan_i2c 0-0015: Elan Touchpad: Module ID: 0x000e, Firmware: 0x0001, Sample: 0x0000, IAP: 0x0000
> 	input: Elan Touchpad as /devices/pci0000:00/0000:00:1f.4/i2c-0/0-0015/input/input21
> 	input: Elan TrackPoint as /devices/pci0000:00/0000:00:1f.4/i2c-0/0-0015/input/input22
> 
> I backported commits
> 
> 	056115daede8 Input: elan_i2c - add new trackpoint report type 0x5F
> 	c7f0169e3bd2 Input: elan_i2c_core - move header inclusion inside
> 
> to this kernel, but this didn't help.
> 
> When enabling smbus tracing the matching events are:
> 
>  irq/159-elan_i2-2207    [003] ....   963.625641: smbus_read: i2c-0 a=015 f=0040 c=a8 BLOCK_DATA
>  irq/159-elan_i2-2207    [003] ....   963.629247: smbus_result: i2c-0 a=015 f=0000 c=a8 BLOCK_DATA rd res=-71
> 
> The relevant code is:
> 
>         len = i2c_smbus_read_block_data(client,
>                                         ETP_SMBUS_PACKET_QUERY,
>                                         &report[ETP_SMBUS_REPORT_OFFSET]);
>         if (len < 0) {
>                 dev_err(&client->dev, "failed to read report data: %d\n", len);
>                 return len;
>         }
> 
> I think the failing location in the i2c driver is
> 
>         if (read_write == I2C_SMBUS_READ ||
>             command == I2C_SMBUS_BLOCK_PROC_CALL) {
>                 len = inb_p(SMBHSTDAT0(priv));
>                 if (len < 1 || len > I2C_SMBUS_BLOCK_MAX)
>                         return -EPROTO;
> 
>                 data->block[0] = len;
>                 for (i = 0; i < len; i++)
>                         data->block[i + 1] = inb_p(SMBBLKDAT(priv));
>         }
> 
> in i801_block_transaction_by_block().
> 
> Does this ring a bell? Does someone know if there is documentation
> available?

I believe Nikolai also run into this issue and is saying that

	modprobe i2c_i801 disable_features=0x2

cures the touchpad.

Thanks.

-- 
Dmitry