* Accessing peripheral register directly from userspace
@ 2010-04-12 17:01 Krishna Gopal
2010-04-13 11:36 ` Clemens Ladisch
0 siblings, 1 reply; 2+ messages in thread
From: Krishna Gopal @ 2010-04-12 17:01 UTC (permalink / raw)
To: linux-kernel
Would there be any issues for optimization purpose I do a mmap to a
peripheral register to directly access it from userspace ? This is
considering the peripheral already has a Kernel driver through which
you can set the register bit.
Basically I want to avoid the additional context switch on entering
the Kernel to set that one bit in the Peripheral register.
I request you to please share your thoughts.
Best regards,
Krishna
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Accessing peripheral register directly from userspace
2010-04-12 17:01 Accessing peripheral register directly from userspace Krishna Gopal
@ 2010-04-13 11:36 ` Clemens Ladisch
0 siblings, 0 replies; 2+ messages in thread
From: Clemens Ladisch @ 2010-04-13 11:36 UTC (permalink / raw)
To: Krishna Gopal; +Cc: linux-kernel
Krishna Gopal wrote:
> Would there be any issues for optimization purpose I do a mmap to a
> peripheral register to directly access it from userspace ?
This means that userspace could access any register in the same page.
Usually this is done only with read-only pages and with devices that
are designed for this so that all accessible registers are 'safe'.
Regards,
Clemens
^ permalink raw reply [flat|nested] 2+ messages in thread
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2010-04-12 17:01 Accessing peripheral register directly from userspace Krishna Gopal
2010-04-13 11:36 ` Clemens Ladisch
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