Re: [PATCH] HID: multitouch: Do not fetch initial feature reports for Win8 devices
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From: Benjamin Tissoires <hidden>
Date: 2015-09-25 01:16:06
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Hi Mika, On Sep 24 2015 or thereabouts, Mika Westerberg wrote:
Some newer Intel Skylake based Dell laptops with Win8 precision touchpad fail when initial feature reports are fetched from it. Below is an
That is unfortunate.
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example output with some additional debug included: i2c_hid i2c-DLL0704:01: Fetching the HID descriptor i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=20 00 i2c_hid i2c-DLL0704:01: HID Descriptor: 1e 00 00 01 99 02 21 00 24 ... ... i2c_hid i2c-DLL0704:01: i2c_hid_get_report i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 38 02 23 00 i2c_hid i2c-DLL0704:01: report (len=4): 04 00 08 05 i2c_hid i2c-DLL0704:01: report id 13 i2c_hid i2c-DLL0704:01: i2c_hid_get_report i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 3d 02 23 00 i2c_hid i2c-DLL0704:01: failed to retrieve report from device. i2c_hid i2c-DLL0704:01: report id 7 i2c_hid i2c-DLL0704:01: i2c_hid_get_report i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 37 02 23 00 i2c_hid i2c-DLL0704:01: report (len=259): 03 01 07 fc 28 fe 84 40 ... i2c_hid i2c-DLL0704:01: report id 4 i2c_hid i2c-DLL0704:01: i2c_hid_get_report i2c_hid i2c-DLL0704:01: __i2c_hid_command: cmd=22 00 34 02 23 00 We manage to fetch few reports but then the touchpad dies: i2c_designware i2c_designware.1: i2c_dw_handle_tx_abort: lost arbitration i2c_hid i2c-DLL0704:01: failed to retrieve report from device. it eventually pulls the whole I2C bus low: i2c_designware i2c_designware.1: controller timed out i2c_hid i2c-DLL0704:01: failed to set a report to device. Fix this by preventing initial feature report fetch for Win8 devices. It should not be needed anyway according to [1] because the two "GET" feature reports for these devices are about device capabilities and Win8 certification status which are not related to input events. [1] https://msdn.microsoft.com/en-us/library/windows/hardware/dn467314(v=vs.85).aspx Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> --- drivers/hid/hid-multitouch.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c index 426b2f1a3450..1911f7698511 100644 --- a/drivers/hid/hid-multitouch.c +++ b/drivers/hid/hid-multitouch.c@@ -1020,14 +1020,16 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id) /* * Handle special quirks for Windows 8 certified devices. */ - if (id->group == HID_GROUP_MULTITOUCH_WIN_8) + if (id->group == HID_GROUP_MULTITOUCH_WIN_8) { /* * Some multitouch screens do not like to be polled for input - * reports. Fortunately, the Win8 spec says that all touches - * should be sent during each report, making the initialization - * of input reports unnecessary. + * and feature reports. Fortunately, the Win8 spec says that all + * touches should be sent during each report, making the + * initialization of input reports unnecessary. */ hdev->quirks |= HID_QUIRK_NO_INIT_INPUT_REPORTS; + hdev->quirks |= HID_QUIRK_NO_INIT_REPORTS;
Problem is that with this quirk, event the features we are interested in (and that the device should support or Microsoft would complain) are not pre-read. I think we should set HID_QUIRK_NO_INIT_REPORTS (and remove HID_QUIRK_NO_INIT_INPUT_REPORTS BTW), and set up a quirk to actually retrieve the value of the feature in mt_feature_mapping. This way, we would be sure to only probe for features that are supported (contact count is the most important one). Cheers, Benjamin
+ }
td = devm_kzalloc(&hdev->dev, sizeof(struct mt_device), GFP_KERNEL);
if (!td) {
--
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