[Lcdproc] [Patch] Protect against overflow in do_mainloop()

[Steve Hill]

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The attached patch protects against the t_diff calculations overflowing in 
do_mainloop().  This can happen if the machine has been suspended (e.g. 
ACPI S3 or S4).

If the calculations would overflow this patch causes the render_lag to be 
reset to RENDER_FREQ and process_lag to be set to 1.  The justification is 
that if we've been suspended, the measured lag is going to be pretty 
useless anyway so this should ensure we do a process and render pass 
immediately.

Obviously most displays won't save state if they're powered down so this 
code doesn't let you suspend a machine and then recover, although I've 
been working on some HAL integration for the CFontz 635 which allows you 
to suspend the machine or unplug the display and then restore the 
display's state when the machine wakes up or your plug it back in again. 
However, the HAL code is nowhere near ready for public consumption. :)

-- 

  - Steve
    xmpp:steve@nexusuk.org   sip:steve@nexusuk.org   http://www.nexusuk.org/

      Servatis a periculum, servatis a maleficum - Whisper, Evanescence

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