Re: [Linuxwacom-devel] [PATCH 2/4] Allow valid case of 2 events per sync windows

[Ping C. <pin...@gm...>]

Overall, the whole patchset is very clean. I like it. Since a few
places affected the protocol 5 devices, I have to test it before I can
let it in. I am tied to another project and Peter is on vacation so
the final review may take sometime. I do have one comment below for
this patch.

Ping

On Mon, Sep 6, 2010 at 5:42 PM,  <ch...@cn...> wrote:
> From: Chris Bagwell <ch...@cn...>
>
> The check to find event sync windows with to little information
> was to agressive.  For example, if only pressure is changing
> then only two events will be sent: ABS_PRESSURE and EV_SYN.
>
> The previous logic would discard in this case.  This is also
> in preparation for simplier tools which do not report serial
> numbers and in general will send small total events per
> sync window.
>
> Also, fixed comment since MSC_SERIAL events are not strictly
> required.
>
> Signed-off-by: Chris Bagwell <ch...@cn...>
> ---
>  src/wcmUSB.c |    7 ++++---
>  1 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/src/wcmUSB.c b/src/wcmUSB.c
> index 4b1806f..72adb0b 100644
> --- a/src/wcmUSB.c
> +++ b/src/wcmUSB.c
> @@ -814,9 +814,10 @@ static void usbParseEvent(InputInfoPtr pInfo,
>        wcmUSBData* private = common->private;
>
>        DBG(10, common, "\n");
> +
>        /* store events until we receive the MSC_SERIAL containing
> -        * the serial number; without it we cannot determine the
> -        * correct channel. */
> +        * the serial number or a SYN_REPORT.
> +        */
>
>        /* space left? bail if not. */
>        if (private->wcmEventCnt >=
> @@ -871,7 +872,7 @@ static void usbParseEvent(InputInfoPtr pInfo,
>        }
>
>        /* ignore events without information */
> -       if ((private->wcmEventCnt <= 2) && private->wcmLastToolSerial)
> +       if ((private->wcmEventCnt < 2) && private->wcmLastToolSerial)

Does this change make a difference to your Bamboo tablet, with both
your new kernel driver and the old linuxwacom kernel driver? I have to
consider backward compatibility seriously since it is my job.

This code was mainly for protocol 5 devices to deal with a few special
cases, such as both stylus and pad (tablet buttons) are in use; or
moving the tablet while touching the tablet buttons. Somehow we get
invalid data.

Ping