Re: [U-Boot] Resubmit : [PATCH] Correct ARM Versatile TimerInitialization

2008-08-18 Thread Gururaja Hebbar K R
Hi,

Today I download u-boot-1.3.4 and checked drivers\rtc directory with 
u-boot-1.3.3\drivers\rtc .

 There is change in the files that this patch touches. So I think the same 
patch can be applied to u-boot-1.3.4 also.

 

Kindly update me if any changes is needed

 

Regards

Gururaja

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Re: [U-Boot] Resubmit : [PATCH] Correct ARM Versatile TimerInitialization

2008-08-15 Thread Gururaja Hebbar K R
Hi 

   Hi,
   
according to datasheet for the register TimerXControl
we are supposed to not modify the bits [31:8] and [4]
so we are suppose to read the register and modify only 
 the others registers/register/bits/
   
   Does this mean i need to resend the earlier patch. Writing 00 to 
   these bits ( 31:8  4) is undefined.
  
  Generally, in ARM terminology, one should avoid writing 
 values where writing a value or bit is undefined.
 
 Not only in ARM.
 
  Undefined implies, not that there is no result, but that 
 the outcome is not defined by the specification.
  Hence it is good practice to read/change/write registers with 
  undefined bits, or bits where writing is undefined.
 
 That exaclty what I mean
 
  This is especially important with bits defined as such in ARM TRMs 
  since different ARM customers may implement the ARM IP in different 
  ways i.e writing a value to such bits may have different results in 
  different implementations and or versions of the hardware.
 
 Thanks Peter for the clarification,


I checked the source code  found that the original code itself modifies
the Timer Control Register directly.

Also, after going through the Timer Module i found that,

For free-running Mode of the timer, Writing to Timer_Load register has
no effect.

The TRM Says,

If the timer is operating in Free-Running Mode, it continues to
decrement from its maximum value

So i think the writing to timer_load register is also unnecessary in
this case. 

Kindly correct me if i am wrong.

Also Kindly let me know, if i need to change anything in the patch.
Else i resend the patch once again

regards
Gururaja
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