On Thu, 8 May 2014, Benjamin Tissoires wrote: > > Reading the partial HID Descriptor is causing a firmware lockup in some > > sensor hubs. Instead of a partial read, this patch implements the > > i2c hid fetch using a fixed descriptor size (30 bytes) followed by a > > verification of the BCDVersion (V01.00), and value stored in > > wHIDDescLength (30 Bytes) for V1.00 descriptors. > > > > As per i2c hid spec, this is the preferred model. > > > > From hid-over-i2c-protocol-spec-v1-0: > > > > There are a variety of ways a HOST may choose to retrieve > > the HID Descriptor from the DEVICE. The following is a preferred > > implementation but should not be considered the only implementation. > > A HOST may read the entire HID Descriptor in a single read by > > issuing a read for 30 Bytes to get the entire HID Descriptor > > from the DEVICE.However, the HOST is responsible for validating that > > > > 1. The BCDVersion is V01.00 (later revisions may have different > > descriptor lengths), and > > > > 2. The value stored in wHIDDescLength is 30 (Bytes) for V1.00 > > descriptors. > > > > Reported-by: Joe Tijerina <joe.tijerina@xxxxxx> > > Signed-off-by: Archana Patni <archana.patni@xxxxxxxxx> > > Signed-off-by: Subramony Sesha <subramony.sesha@xxxxxxxxx> > > Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> > > --- > > This one is Reviewed-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> Do we have any indication about how frequently are the lockups actually happening in the wild? Is this a regression? (I don't think so). The reason I am asking is whether I should rush this in for 3.15 still, but as the patch doesn't have stable annotation anyway, my understanding is that 3.16 is enough? Thanks, -- Jiri Kosina SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
