[RFC] [Patch 0/4] ACPI : several patches for EC

[Zhao Yakui <yakui.zhao@xxxxxxxxx>]

Hi, All
 
    The following are several patches for EC driver.
    
     Patch 1/4: Don't issue the burst disable command if EC exits the
burst mode
     It is meaningless that OS continues to issue the burst disable
command if the EC already exists the burst mode. So if EC already exists
the burst mode, don't issue burst disable command again.
     If OS continues to issue the burst disable command, there exist
some meaningless ACPI interrupts.
   
    Patch 2/4: Simplify EC working flowchart and always enable EC GPE 
    In current kernel the EC driver will be started in polling mode. When the EC
GPE interrupt is triggered, it will be switched to EC GPE interrupt mode.
And when there is no EC GPE confirmation for some EC transaction on some broken
laptops,the EC driver will be switched to polling mode and EC GPE will be
disabled. In such case the EC notification event will be lost.
        For example: Bug 11428/8459
    http://bugzilla.kernel.org/show_bug.cgi?id=11428

    But if the EC GPE is still enable although switching to polling mode, the EC
notification event won't be lost.
    
    In the patch the EC default work mode will be interrupt-driven while EC driver
is started. Only when there is no EC GPE interrupt for some EC transactions, it 
will be switched to polling mode. But EC GPE is still enabled.

    Patch 3/4: Add some delay in EC GPE handler to workaround EC GPE storm
    On some broken BIOS there exists the EC GPE interrupt storm. It means that there exist
too many ACPI interrupts related with EC GPE.
    If the EC GPE is still enabled, it will cause that keystrokes will be lost and 
the system can't work well. For example: 
    http://bugzilla.kernel.org/show_bug.cgi?id=9998

	If the EC GPE is disabled after EC GPE storm happens, some system will be unstable.
     http://bugzilla.kernel.org/show_bug.cgi?id=10724

     And on some laptops with "incorrect EC status before EC GPE arrives" OS will
report the incorrect thermal temperature if EC GPE is disabled while EC GPE storm happens.
    http://bugzilla.kernel.org/show_bug.cgi?id=11309

    This patch is to add some delay in EC GPE handler on some broken
BIOS.Only when more than five interrupts happen in the same jiffies and
EC status are the same, OS will add some delay in the EC GPE handler. If
the same issue still happens after adding delay,the delay time will be
increased.But the max delay time is ten microseconds.
   In such case the EC GPE is still enabled although EC GPE storm happens. And EC driver
will continue to work in interrupt-driven mode. But the number of EC GPE interrupts can
be reduced very significantly.

   I know that this method is ugly. Some delay is added in the EC GPE handler(interrupt context).
But no delay is added on the normal laptops. It only workarounds the broken laptops.
    
    Patch 4/4: Cleanup some useless code in EC driver
    If the above three patches are applied, there exist some useless code. Cleanup it.
    

Thanks for the comments.
  Yakui


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