On 04/21/2013 05:10 PM, Ján Veselý wrote: > On Sun, Apr 21, 2013 at 4:21 PM, Martin Sucha <[email protected]> wrote: >> Hi, >> >> On 04/21/2013 03:52 PM, Ján Veselý wrote: >>> There is no way for ps2 driver to know whether an interrupt event can >>> be safely dropped, dropping one part of a message desync and breaks >>> ps2 protocol, >> I don't know how PS/2 protocol works, but I'm wondering, couldn't the >> keyboard/mouse driver recover from the data drop if it knew it occured? >> Like send a reset command to the device or something? (I know an >> isdv4-based tablet device could be reset if necessary) > > the mouse can be reset if we know there is a protocol error, the > problem is detecting those errors. We can at least detect the protocol errors caused by us dropping the bytes from the stream (i8042 can inform the consumer of the stream that it dropped some bytes from the stream. <OT>This might even be a good idea to do also for the serial port where the driver can detect hardware buffer overruns etc.</OT>)
> you can see the packet format here: > http://www.computer-engineering.org/ps2mouse/ > > in the basic version there is only one bit hardset to 1, in the > 3-button intellimouse version there is an addition of z-axis with > limited range 5-button intellimouse version there are two more bits > hardwired to 0, the rest are legal values. Basic checks on those > values is possible but I don't think it would reliable, in general > you'll need to check 'sanity' of mouse movements/clicks. OK, thanks for info. Martin Sucha _______________________________________________ HelenOS-devel mailing list [email protected] http://lists.modry.cz/cgi-bin/listinfo/helenos-devel
