From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from wolverine01.qualcomm.com ([199.106.114.254]:14986 "EHLO wolverine01.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751913Ab0HFXJH (ORCPT ); Fri, 6 Aug 2010 19:09:07 -0400 Message-ID: <4C5C9606.7040304@codeaurora.org> Date: Fri, 06 Aug 2010 16:08:54 -0700 From: Stepan Moskovchenko MIME-Version: 1.0 Subject: Re: [PATCH] arm: msm: Add MSM IOMMU support. References: <1281062204-21880-1-git-send-email-stepanm@codeaurora.org> <20100806073333.GA14965@n2100.arm.linux.org.uk> <93bd044b61aed19a3571bc019af0252a.squirrel@www.codeaurora.org> <20100806085941.GA15852@n2100.arm.linux.org.uk> In-Reply-To: <20100806085941.GA15852@n2100.arm.linux.org.uk> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-arm-msm-owner@vger.kernel.org List-ID: To: Russell King - ARM Linux Cc: dwalker@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org On 8/6/2010 1:59 AM, Russell King - ARM Linux wrote: > 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. > -- > To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Russell, Thanks for the information. Getting the clock by the device as you suggest should be fine. I believe I have addressed your other comments as well. I've sent out a v2 patch. Please let me know what you think. Thanks Steve