Re: kern/53444: extended W mode enabling makes vt-switching very slow

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

The following reply was made to PR kern/53444; it has been noted by GNATS.

From: Valery Ushakov <uwe%stderr.spb.ru@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: kern/53444: extended W mode enabling makes vt-switching very slow
Date: Fri, 13 Jul 2018 01:27:32 +0300

 On Thu, Jul 12, 2018 at 21:20:00 +0000, coypu%sdf.org@localhost wrote:
 
 >  uwe mentions this:
 >  
 >                      0xe6, 0xe8, 0x00, 0xe8, 0x00,
 >                      0xe8, 0x00, 0xe8, 0x03, 0xf3,
 >                      0xc8,
 >  
 >  effectively hard-codes the 'psmouse sliced command' which multiple
 >  things use (and then some).
 >  
 >  In the words of otherOS:
 >  
 >   * psmouse_sliced_command() sends an extended PS/2 command to the mouse
 >   * using sliced syntax, understood by advanced devices, such as Logitech
 >   * or Synaptics touchpads. The command is encoded as:
 >   * 0xE6 0xE8 rr 0xE8 ss 0xE8 tt 0xE8 uu where (rr*64)+(ss*16)+(tt*4)+uu
 >  
 >  The documentation/other drivers use sliced commands.
 
 - E6 makes sure we are in a known state (just in case previous command was E8)
 - E8 xx ... sends the argument for the extended command in slices
 - F3 xx is the command
 
 FWIW, the docs I have say that F3 C8 sets Deluxe Mode Byte 3 but they
 are rather old and that byte is unused/undocumented in them.
 
 I wonder if the device is unhappy b/c you send that extended command
 byte by byte instead of using pms_sliced_command() that will send it
 in meaningful chunks.
 
 -uwe