From mboxrd@z Thu Jan 1 00:00:00 1970 From: Scott Wood Subject: Re: [PATCH 4/4 v4] iommu/fsl: Freescale PAMU driver and IOMMU API implementation. Date: Mon, 5 Nov 2012 17:11:15 -0600 Message-ID: <1352157075.28279.10@snotra> References: <1352114361-25192-1-git-send-email-Varun.Sethi@freescale.com> <1352114361-25192-2-git-send-email-Varun.Sethi@freescale.com> <1352114361-25192-3-git-send-email-Varun.Sethi@freescale.com> <1352114361-25192-4-git-send-email-Varun.Sethi@freescale.com> <509845ED.2060904@freescale.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; delsp=Yes; format=Flowed Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: <509845ED.2060904@freescale.com> (from timur@freescale.com on Mon Nov 5 17:04:13 2012) Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: Timur Tabi Cc: Varun Sethi , joerg.roedel@amd.com, iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org List-Id: iommu@lists.linux-foundation.org On 11/05/2012 05:04:13 PM, Timur Tabi wrote: > Varun Sethi wrote: > > + /* PAACE Offset 0x00 */ > > + u32 wbah; /* only valid for > Primary PAACE */ > > + u32 addr_bitfields; /* See P/S PAACE_AF_* */ > > + > > + /* PAACE Offset 0x08 */ > > + /* Interpretation of first 32 bits dependent on DD above */ > > + union { > > + struct { > > + /* Destination ID, see PAACE_DID_* defines */ > > + u8 did; > > + /* Partition ID */ > > + u8 pid; > > + /* Snoop ID */ > > + u8 snpid; > > + /* coherency_required : 1 reserved : 7 */ > > Please use this format, which is easier to read: > > /* 1 == coherency required, 7 == reserved */ > > Every time I look at this comment, I think you are using bitfields. It is meant as a pseudo-bitfield. "7 == reserved" doesn't make much sense -- that would leave a lot of other values neither defined nor explicitly reserved. That said, the "See PAACE_DA_*" comment should be sufficient and avoids making people have to care about what bitfield ordering the comment writer was assuming. -Scott