On Tue, 2 Apr 2024, Mark Pearson wrote: > On Tue, Apr 2, 2024, at 7:10 AM, Hans de Goede wrote: > > From: Kenny Levinsen <kl@xxxxxx> > > > > In af93a167eda9, i2c_hid_parse was changed to continue with reading the > > report descriptor before waiting for reset to be acknowledged. > > > > This has lead to two regressions: > > > > 1. We fail to handle reset acknowledgment if it happens while reading > > the report descriptor. The transfer sets I2C_HID_READ_PENDING, which > > causes the IRQ handler to return without doing anything. > > > > This affects both a Wacom touchscreen and a Sensel touchpad. > > > > 2. On a Sensel touchpad, reading the report descriptor this quickly > > after reset results in all zeroes or partial zeroes. > > > > The issues were observed on the Lenovo Thinkpad Z16 Gen 2. > > > > The change in question was made based on a Microsoft article[0] stating > > that Windows 8 *may* read the report descriptor in parallel with > > awaiting reset acknowledgment, intended as a slight reset performance > > optimization. Perhaps they only do this if reset is not completing > > quickly enough for their tastes? > > > > As the code is not currently ready to read registers in parallel with a > > pending reset acknowledgment, and as reading quickly breaks the report > > descriptor on the Sensel touchpad, revert to waiting for reset > > acknowledgment before proceeding to read the report descriptor. > > > > [0]: > > https://learn.microsoft.com/en-us/windows-hardware/drivers/hid/plug-and-play-support-and-power-management > > > > Fixes: af93a167eda9 ("HID: i2c-hid: Move i2c_hid_finish_hwreset() to > > after reading the report-descriptor") > > Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2271136 > > Cc: stable@xxxxxxxxxxxxxxx > > Signed-off-by: Kenny Levinsen <kl@xxxxxx> > > Link: https://lore.kernel.org/r/20240331182440.14477-1-kl@xxxxxx > > [hdegoede@xxxxxxxxxx Drop no longer necessary abort_reset error exit > > path] > > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> [ .. snip .. ] > Tested on my Z13 G2 system and confirmed this fixes the issue. > > Tested-by: Mark Pearson <mpearson-lenovo@xxxxxxxxx> Applied to hid.git#for-6.9/upstream-fixes. Thanks, -- Jiri Kosina SUSE Labs
