Re: [PATCHv3 2/2] msm: Support DEBUG_LL on MSM8660 and MSM8960

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On 11/08/11 11:08, Nicolas Pitre wrote:
>> +	.macro	senduart, rd, rx
>> +	@ Write the 1 character to UARTDM_TF
>> +	str	\rd, [\rx, #0x70]
>> +#else
>>  	teq	\rx, #0
>>  	strne	\rd, [\rx, #0x0C]
>> +#endif
>>  	.endm
> Why testing for zero in the #else part?  The upper level code should 
> never call this macro with a null byte.

Ok I poked into the git logs (thanks Bryan). It was first introduced in
bcc0f6a ([ARM] msm: clean up iomap and devices, 2008-09-10). It seems
that debug_ll support on MSM at the time had to remove the virtual
mapping for the uart base. Thus when the MMU was enabled the addruart
macro returned 0 and the senduart macro would test for 0 so that
senduart could disable debug_ll when the MMU was enabled. Something
about "problems with the peripheral window".

Later on, the virtual mapping was added back in 6339f66 (msm: make
debugging UART (for DEBUG_LL) configurable, 2009-11-02) but the patch
forgot to remove the teq. So as it stands the teq has been useless for
two years.

Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

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