Messages in this thread | | | Date | Fri, 6 Aug 2010 09:59:41 +0100 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH] arm: msm: Add MSM IOMMU support. |
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On Fri, Aug 06, 2010 at 01:17:46AM -0700, stepanm@codeaurora.org wrote: > Thank you for your comments. I will apply the fixes you have mentioned. I > am flushing the cache when I update the page table because the page table > lives in regular RAM that is mapped as cacheable on the CPU side, and in > the default configuration the IOMMU reads the page table from RAM.
That's fine, but use the right function.
> So, I > have put in the flush call to give the IOMMU a coherent view of the page > tables. I realize it is more efficient to just flush that specific part of > L2, but this is just the basic version of the driver and that optimization > will be eventually put in.
Here, you're talking about L2 again, but your code only touches the L1 cache. I think you're confused about caching.
> What did you mean by: > > Any reason you can't have some kind of struct device instead? > > Are you referring to the clock line? As far as I understand it, the kernel > tracks the clocks by a string name, but I can look into it further.
No.
/** * clk_get - lookup and obtain a reference to a clock producer. * @dev: device for clock "consumer" * @id: clock comsumer ID * * Returns a struct clk corresponding to the clock producer, or * valid IS_ERR() condition containing errno. The implementation * uses @dev and @id to determine the clock consumer, and thereby * the clock producer. (IOW, @id may be identical strings, but * clk_get may return different clock producers depending on @dev.)
The intention is that 'id' is specific to each 'dev', and identifies the connection on 'dev' that you want the clock for. It's the _consumer's_ name, nothing to do with the clock producer.
There's also clk_get_sys() if you don't have a struct device.
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