Author: Patrick Doyle Date: To: balloon Subject: Re: [Balloon] Should SA_SDCLK0 be wiggling on my Balloon board?
On Wed, Jul 6, 2011 at 11:57 AM, Patrick Doyle <firstname.lastname@example.org> wrote: > Before I go too far down this path, I figured I should just ask the question...
> The SDCLK<0> output pin on the PXA270 is wired to SA_SDCLK0, which is
> wired to pin Y11 on the FPGA. I would like to run some synchronous
> logic (specifically, a dual clocked FIFO) off of this clock. Right
> now, it doesn't seem to be wiggling. I can think of 2 reasons
> immediately why I might not see it wiggling:
> 1) I did something wrong.
> 2) It doesn't wiggle unless it is configured to do so, and the default
> kernel doesn't configure it to wiggle.
> I'm working on trying to figure out option (1). I thought I should
> ask you folks about option (2).
> It seems like I need to set the K0FREE bit of the MDREFR register. I
can do that fairly easily and hackilly by just OR-ing MDREFR_K0FREE
into MDREFR inside a loadable kernel module.
Is there a better (kernel or even user space) API for examining and
manipulating bits in MDREFR and other registers?
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