On Fri, 7 Jan 2022, Dmitry Torokhov wrote:
> Unfortunately details of USB HID transport bled into HID core and
> handling of numbered/unnumbered reports is quite a mess, with
> hid_report_len() calculating the length according to USB rules,
> and hid_hw_raw_request() adding report ID to the buffer for both
> numbered and unnumbered reports.
Yeah, I agree that's unfortunate, and untangling this has been on my TODO
for quite some time :/
> Fixes: 14c9c014babe ("HID: add vivaldi HID driver")
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> ---
>
> CrOS folks, please help testing this as I do not have the affected
> hardware.
>
> Thanks!
>
> drivers/hid/hid-vivaldi.c | 34 ++++++++++++++++++++++++++++------
> 1 file changed, 28 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/hid/hid-vivaldi.c b/drivers/hid/hid-vivaldi.c
> index cd7ada48b1d9..1804de1ef9b8 100644
> --- a/drivers/hid/hid-vivaldi.c
> +++ b/drivers/hid/hid-vivaldi.c
> @@ -71,10 +71,11 @@ static void vivaldi_feature_mapping(struct hid_device *hdev,
> struct hid_usage *usage)
> {
> struct vivaldi_data *drvdata = hid_get_drvdata(hdev);
> + struct hid_report *report = field->report;
> int fn_key;
> int ret;
> u32 report_len;
> - u8 *buf;
> + u8 *report_data, *buf;
>
> if (field->logical != HID_USAGE_FN_ROW_PHYSMAP ||
> (usage->hid & HID_USAGE_PAGE) != HID_UP_ORDINAL)
> @@ -86,12 +87,24 @@ static void vivaldi_feature_mapping(struct hid_device *hdev,
> if (fn_key > drvdata->max_function_row_key)
> drvdata->max_function_row_key = fn_key;
>
> - buf = hid_alloc_report_buf(field->report, GFP_KERNEL);
> - if (!buf)
> + report_data = buf = hid_alloc_report_buf(report, GFP_KERNEL);
> + if (!report_data)
> return;
>
> - report_len = hid_report_len(field->report);
> - ret = hid_hw_raw_request(hdev, field->report->id, buf,
> + report_len = hid_report_len(report);
> + if (!report->id) {
> + /*
> + * hid_hw_raw_request() will stuff report ID (which will be 0)
> + * into the first byte of the buffer even for unnumbered
> + * reports, so we need to account for this to avoid getting
> + * -EOVERFLOW in return.
> + * Note that hid_alloc_report_buf() adds 7 bytes to the size
> + * so we can safely say that we have space for an extra byte.
> + */
> + report_len++;
> + }
> +
> + ret = hid_hw_raw_request(hdev, field->report->id, report_data,
I've changed this to report->id and applied, thanks.
--
Jiri Kosina
SUSE Labs
