A recent bug made me look at Microsoft's i2c-hid docs again and I noticed the following: """ 4. Issue a RESET (Host Initiated Reset) to the Device. 5. Retrieve report descriptor from the device. Note: Steps 4 and 5 may be done in parallel to optimize for time on I²C. Since report descriptors are (a) static and (b) quite long, Windows 8 may issue a request for 5 while it is waiting for a response from the device on 4. """ Which made me think that maybe on some touchpads the reset ack is delayed till after the report descriptor is read ? Testing a T-BAO Tbook Air 12.5 with a 0911:5288 (SIPODEV SP1064?) touchpad, for which the I2C_HID_QUIRK_NO_IRQ_AFTER_RESET quirk was first introduced, shows that about 1 ms after the report descriptor read finishes the reset indeed does get acked. Move the waiting for the ack to after reading the report-descriptor, so that the I2C_HID_QUIRK_NO_IRQ_AFTER_RESET quirk is no longer necessary (on this model). While at it drop the dbg_hid() for a malloc failure, malloc failures already get logged extensively by malloc itself. Link: https://bugzilla.redhat.com/show_bug.cgi?id=2247751 Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- drivers/hid/i2c-hid/i2c-hid-core.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c index f029ddce4766..3bd0c3d77d99 100644 --- a/drivers/hid/i2c-hid/i2c-hid-core.c +++ b/drivers/hid/i2c-hid/i2c-hid-core.c @@ -502,6 +502,12 @@ static int i2c_hid_finish_hwreset(struct i2c_hid *ihid) return ret; } +static void i2c_hid_abort_hwreset(struct i2c_hid *ihid) +{ + clear_bit(I2C_HID_RESET_PENDING, &ihid->flags); + mutex_unlock(&ihid->reset_lock); +} + static void i2c_hid_get_input(struct i2c_hid *ihid) { u16 size = le16_to_cpu(ihid->hdesc.wMaxInputLength); @@ -746,8 +752,6 @@ static int i2c_hid_parse(struct hid_device *hid) do { ret = i2c_hid_start_hwreset(ihid); - if (ret == 0) - ret = i2c_hid_finish_hwreset(ihid); if (ret) msleep(1000); } while (tries-- > 0 && ret); @@ -763,9 +767,8 @@ static int i2c_hid_parse(struct hid_device *hid) i2c_hid_dbg(ihid, "Using a HID report descriptor override\n"); } else { rdesc = kzalloc(rsize, GFP_KERNEL); - if (!rdesc) { - dbg_hid("couldn't allocate rdesc memory\n"); + i2c_hid_abort_hwreset(ihid); return -ENOMEM; } @@ -776,10 +779,21 @@ static int i2c_hid_parse(struct hid_device *hid) rdesc, rsize); if (ret) { hid_err(hid, "reading report descriptor failed\n"); + i2c_hid_abort_hwreset(ihid); goto out; } } + /* + * Windows directly reads the report-descriptor after sending reset + * and then waits for resets completion afterwards. Some touchpads + * actually wait for the report-descriptor to be read before signalling + * reset completion. + */ + ret = i2c_hid_finish_hwreset(ihid); + if (ret) + goto out; + i2c_hid_dbg(ihid, "Report Descriptor: %*ph\n", rsize, rdesc); ret = hid_parse_report(hid, rdesc, rsize); -- 2.41.0
