6.8-stable review patch. If anyone has any objections, please let me know.
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From: Kenny Levinsen kl@kl.wtf
commit ea36bf1827462e4a52365bf8e3f7d1712c5d9600 upstream.
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...
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@vger.kernel.org Signed-off-by: Kenny Levinsen kl@kl.wtf Link: https://lore.kernel.org/r/20240331182440.14477-1-kl@kl.wtf [hdegoede@redhat.com Drop no longer necessary abort_reset error exit path] Signed-off-by: Hans de Goede hdegoede@redhat.com Tested-by: Mark Pearson mpearson-lenovo@squebb.ca Signed-off-by: Jiri Kosina jkosina@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/hid/i2c-hid/i2c-hid-core.c | 29 ++++++++--------------------- 1 file changed, 8 insertions(+), 21 deletions(-)
diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c index 1c86c97688e9..d965382196c6 100644 --- a/drivers/hid/i2c-hid/i2c-hid-core.c +++ b/drivers/hid/i2c-hid/i2c-hid-core.c @@ -726,12 +726,15 @@ static int i2c_hid_parse(struct hid_device *hid) mutex_lock(&ihid->reset_lock); do { ret = i2c_hid_start_hwreset(ihid); - if (ret) + if (ret == 0) + ret = i2c_hid_finish_hwreset(ihid); + else msleep(1000); } while (tries-- > 0 && ret); + mutex_unlock(&ihid->reset_lock);
if (ret) - goto abort_reset; + return ret;
use_override = i2c_hid_get_dmi_hid_report_desc_override(client->name, &rsize); @@ -741,11 +744,8 @@ 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) { - ret = -ENOMEM; - goto abort_reset; - } + if (!rdesc) + return -ENOMEM;
i2c_hid_dbg(ihid, "asking HID report descriptor\n");
@@ -754,23 +754,10 @@ static int i2c_hid_parse(struct hid_device *hid) rdesc, rsize); if (ret) { hid_err(hid, "reading report descriptor failed\n"); - goto abort_reset; + 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); -abort_reset: - clear_bit(I2C_HID_RESET_PENDING, &ihid->flags); - mutex_unlock(&ihid->reset_lock); - if (ret) - goto out; - i2c_hid_dbg(ihid, "Report Descriptor: %*ph\n", rsize, rdesc);
ret = hid_parse_report(hid, rdesc, rsize);