> On Dec 19, 2018, at 21:09, Jiri Kosina <ji...@kernel.org> wrote:
>
> On Fri, 14 Dec 2018, Kai-Heng Feng wrote:
>
>> While using Elan touchpads, the message floods:
>> [ 136.138487] i2c_hid i2c-DELL08D6:00: i2c_hid_get_input: incomplete report
>> (14/65535)
>>
>> Though the message flood is annoying, the device it self works without
>> any issue. I suspect that the device in question takes too much time to
>> pull the IRQ back to high after I2C host has done reading its data.
>>
>> Since the host receives all useful data, let's ignore the input report
>> when there's no data.
>
> Interesting, never seen such a bug before.
>
>> Signed-off-by: Kai-Heng Feng <kai.heng.f...@canonical.com>
>> ---
>> drivers/hid/i2c-hid/i2c-hid-core.c | 9 +++++++++
>> 1 file changed, 9 insertions(+)
>>
>> diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c
>> b/drivers/hid/i2c-hid/i2c-hid-core.c
>> index 8555ce7e737b..1776afa6d69c 100644
>> --- a/drivers/hid/i2c-hid/i2c-hid-core.c
>> +++ b/drivers/hid/i2c-hid/i2c-hid-core.c
>> @@ -50,6 +50,7 @@
>> #define I2C_HID_QUIRK_NO_IRQ_AFTER_RESET BIT(1)
>> #define I2C_HID_QUIRK_NO_RUNTIME_PM BIT(2)
>> #define I2C_HID_QUIRK_DELAY_AFTER_SLEEP BIT(3)
>> +#define I2C_HID_QUIRK_BOGUS_IRQ BIT(4)
>>
>> /* flags */
>> #define I2C_HID_STARTED 0
>> @@ -179,6 +180,8 @@ static const struct i2c_hid_quirks {
>> I2C_HID_QUIRK_DELAY_AFTER_SLEEP },
>> { USB_VENDOR_ID_LG, I2C_DEVICE_ID_LG_8001,
>> I2C_HID_QUIRK_NO_RUNTIME_PM },
>> + { USB_VENDOR_ID_ELAN, HID_ANY_ID,
>> + I2C_HID_QUIRK_BOGUS_IRQ },
>> { 0, 0 }
>> };
>>
>> @@ -503,6 +506,12 @@ static void i2c_hid_get_input(struct i2c_hid *ihid)
>> return;
>> }
>>
>> + if (ihid->quirks & I2C_HID_QUIRK_BOGUS_IRQ && ret_size == 0xffff) {
>> + dev_dbg(&ihid->client->dev,
>> + "%s: IRQ triggered but there's no data\n", __func__);
>> + return;
>> + }
>
> Would it perhaps make sense to make this some sort of printk_once(), so
> that it's immediately apparent from dmesg that the system/device is
> suffering from this particular problem? Might potentially be helpful piece
> of information.
Good advice, I’ll send a v2 patch to address this issue.
Kai-Heng
>
> Thanks,
>
> --
> Jiri Kosina
> SUSE Labs
>
