[RFC] Option to disable mapping genrtc calls to ppc_md calls

Dan Malek dan at embeddededge.com
Wed Jan 19 03:25:33 EST 2005

On Jan 18, 2005, at 11:15 AM, Tom Rini wrote:

> On Mon, Jan 17, 2005 at 02:10:00PM -0700, Mark A. Greer wrote:

>> There are 2 reasons to not use the ppc_md.get_rtc_time() et. al. 
>> interfaces:
>> 1) They are called before the i2c driver is initialized and even 
>> loaded
>> if its a module.

There are three reasons.  You don't want to use an I2c rtc clock at
all in these functions because they get can get called from the
clock interrupt to update the time in the rtc.  If it does happen to 
it creates long latencies in the timer interrupt.  If the i2c requires 
interrupt, they system will crash or hang.

A system using an I2C RTC should find some way to access the
clock from application space as a standard I2C device and manage
time/clock from the application, not from the kernel.

	-- Dan

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