From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCHv7 10/12] iommu/tegra: smmu: allow duplicate ASID wirte Date: Mon, 16 Dec 2013 12:19:37 -0700 Message-ID: <52AF5249.6050802@wwwdotorg.org> References: <1386835033-4701-1-git-send-email-hdoyu@nvidia.com> <1386835033-4701-11-git-send-email-hdoyu@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1386835033-4701-11-git-send-email-hdoyu-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Hiroshi Doyu , swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org Cc: mark.rutland-5wv7dgnIgG8@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org On 12/12/2013 12:57 AM, Hiroshi Doyu wrote: > The device, which belongs to the same ASID, can try to enable the same > ASID as the other swgroup devices. This should be allowed but just > skip the actual register write. If the write value is different, it > will return -EINVAL. I guess this simplifies the body of the code a lot. Given this, I would revise the code I suggested in response to a previous patch, to something more like: offs = HWGRP_ASID_REG(i); val = smmu_read(smmu, offs); if (on) { if (WARN_ON(val && val != new_val)) return -ENODEV; memcpy(c->hwgrp, map, sizeof(u64)); } else { WARN_ON(val); } smmu_write(smmu, val, offs); > + if (val) { > + if (WARN_ON(val != mask)) > + return -EINVAL; > + goto skip; That means that: a) No error is returned when the ASIDs don't match. Surely you still want to return an error? b) "skip" skips setting up all HWGRP IDs for the device, whereas perhaps only 1 was shared yet the rest still need to be set up. If you really do want to ignore the error, then surely you want "continue;" here not "goto skip;"? > + } ... > +skip: > return 0;