On Tuesday 16 December 2014 09:33:44 Benjamin Tissoires wrote:
> On Mon, Dec 15, 2014 at 7:50 PM, Peter Wu <peter@xxxxxxxxxxxxx> wrote:
> > Devices speaking HID++ 2.0 report a different error code (0xff). Detect
> > these errors too to avoid 5 second delays when the device reports an
> > error. Caught by... well, a bug in the QEMU emulation of this receiver.
> >
> > Renamed fap to rap for HID++ 1.0 errors because it is more logical,
> > it has no functional difference.
> >
> > Signed-off-by: Peter Wu <peter@xxxxxxxxxxxxx>
> > ---
>
> I'd like to have Nestor's opinion on this. I did not manage to find on
> the documentation that HID++ 2.0 Long report error code is 0xff, so
> introducing this change without Logitech's blessing would be
> unfortunate.
> I understand this will fix your qemu problem, but I am not entirely
> sure if we do not have to check on 0xff and 0x8f in both short and
> long responses.
>
> Cheers,
> Benjamin
The error code was found by probing the hardware. The HID++ 2.0 spec
does define some error codes, for example an OutOfRange error when
GetFeatureID is called with a featureIndex greater than the available
features count. The documentation also defines the valid FeatureIndex
range as 1..254, so I thought it was reasonable to assume that 0xff is
the HID++ 2.0 error indicator.
Nestor, so far I have only seen the OutOfRange error when the arguments
are invalid. Are there other cases where HID++ 2.0 are reported instead
of HID++ 1.0?
QEMU was not the problem though, it was just a bug in my
usb-ltunify-receiver device emulation which exposed this missing check.
Kind regards,
Peter
> > drivers/hid/hid-logitech-hidpp.c | 17 ++++++++++++++---
> > 1 file changed, 14 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
> > index 2f420c0..ae23dec 100644
> > --- a/drivers/hid/hid-logitech-hidpp.c
> > +++ b/drivers/hid/hid-logitech-hidpp.c
> > @@ -105,6 +105,7 @@ struct hidpp_device {
> > };
> >
> >
> > +/* HID++ 1.0 error codes */
> > #define HIDPP_ERROR 0x8f
> > #define HIDPP_ERROR_SUCCESS 0x00
> > #define HIDPP_ERROR_INVALID_SUBID 0x01
> > @@ -119,6 +120,8 @@ struct hidpp_device {
> > #define HIDPP_ERROR_REQUEST_UNAVAILABLE 0x0a
> > #define HIDPP_ERROR_INVALID_PARAM_VALUE 0x0b
> > #define HIDPP_ERROR_WRONG_PIN_CODE 0x0c
> > +/* HID++ 2.0 error codes */
> > +#define HIDPP20_ERROR 0xff
> >
> > static void hidpp_connect_event(struct hidpp_device *hidpp_dev);
> >
> > @@ -192,9 +195,16 @@ static int hidpp_send_message_sync(struct hidpp_device *hidpp,
> > }
> >
> > if (response->report_id == REPORT_ID_HIDPP_SHORT &&
> > - response->fap.feature_index == HIDPP_ERROR) {
> > + response->rap.sub_id == HIDPP_ERROR) {
> > + ret = response->rap.params[1];
> > + dbg_hid("%s:got hidpp error %02X\n", __func__, ret);
> > + goto exit;
> > + }
> > +
> > + if (response->report_id == REPORT_ID_HIDPP_LONG &&
> > + response->fap.feature_index == HIDPP20_ERROR) {
> > ret = response->fap.params[1];
> > - dbg_hid("__hidpp_send_report got hidpp error %02X\n", ret);
> > + dbg_hid("%s:got hidpp 2.0 error %02X\n", __func__, ret);
> > goto exit;
> > }
> >
> > @@ -271,7 +281,8 @@ static inline bool hidpp_match_answer(struct hidpp_report *question,
> > static inline bool hidpp_match_error(struct hidpp_report *question,
> > struct hidpp_report *answer)
> > {
> > - return (answer->fap.feature_index == HIDPP_ERROR) &&
> > + return ((answer->rap.sub_id == HIDPP_ERROR) ||
> > + (answer->fap.feature_index == HIDPP20_ERROR)) &&
> > (answer->fap.funcindex_clientid == question->fap.feature_index) &&
> > (answer->fap.params[0] == question->fap.funcindex_clientid);
> > }
> > --
> > 2.1.3
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