#11041 NORM 1.75-so: XO-1.75 A3 #4 accelerometer may hang

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#11041: XO-1.75 A3 #4 accelerometer may hang
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           Reporter:  Quozl   |       Owner:  buytenh                          
               Type:  defect  |      Status:  new                              
           Priority:  normal  |   Milestone:  1.75-software                    
          Component:  kernel  |     Version:  Development build as of this date
         Resolution:          |    Keywords:  XO-1.75, accelerometer           
        Next_action:  code    |    Verified:  0                                
Deployment_affected:          |   Blockedby:                                   
           Blocking:          |  
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Changes (by wad):

  * next_action:  never set => code
  * component:  not assigned => kernel
  * owner:  => buytenh
  * version:  not specified => Development build as of this date
  * milestone:  1.75-firmware => 1.75-software
  * keywords:  => XO-1.75, accelerometer


Comment:

 This is definitely the same issue as #10882.

 We need to ensure that the I2C bus for the accelerometer runs at around 25
 KHz on A3/B1 motherboards.   We will fix the hardware to allow full speed
 operation starting with C1.

 The value written to the LSR field of the TWSI_LCR register on the I2C bus
 talking to the accelerometer should be 0X1FF, not the default 0x7E.   This
 has already been fixed in OFW, starting with Q4B05, but the Linux driver
 might also need to be patched.

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Ticket URL: <http://dev.laptop.org/ticket/11041#comment:3>
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