From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sricharan R Subject: Re: [PATCH v6 4/6] iommu/arm-smmu: Add the device_link between masters and smmu Date: Fri, 2 Feb 2018 11:10:25 +0530 Message-ID: <7cc4caec-4264-db9d-3afa-e3d20d3edfa7@codeaurora.org> References: <1516362223-22946-1-git-send-email-vivek.gautam@codeaurora.org> <1516362223-22946-5-git-send-email-vivek.gautam@codeaurora.org> <6b930150-cb81-b0a5-601c-16cb576c4341@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Content-Language: en-US Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Vivek Gautam , Robin Murphy , alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, rjw-LthD3rsA81gm4RdzfppkhA@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, freedreno-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, sboyd-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org Cc: gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org, architt-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, linux-arm-msm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: iommu@lists.linux-foundation.org Hi Robin/Vivek, On 2/1/2018 2:23 PM, Vivek Gautam wrote: > Hi, > > > On 1/31/2018 6:39 PM, Robin Murphy wrote: >> On 19/01/18 11:43, Vivek Gautam wrote: >>> From: Sricharan R >>> >>> Finally add the device link between the master device and >>> smmu, so that the smmu gets runtime enabled/disabled only when the >>> master needs it. This is done from add_device callback which gets >>> called once when the master is added to the smmu. >> >> Don't we need to balance this with a device_link_del() in .remove_device (like exynos-iommu does)? > > Right. Will add device_link_del() call. Thanks for pointing out. The reason for not adding device_link_del from .remove_device was, the core device_del which calls the .remove_device from notifier, calls device_links_purge before that. That does the same thing as device_link_del. So by the time .remove_device is called, device_links for that device is already cleaned up. Vivek, you may want to check once that calling device_link_del from .remove_device has no effect, just to confirm once more. Regards, Sricharan > > regards > Vivek > >> >> Robin. >> >>> Signed-off-by: Sricharan R >>> --- >>>   drivers/iommu/arm-smmu.c | 11 +++++++++++ >>>   1 file changed, 11 insertions(+) >>> >>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c >>> index 95478bfb182c..33bbcfedb896 100644 >>> --- a/drivers/iommu/arm-smmu.c >>> +++ b/drivers/iommu/arm-smmu.c >>> @@ -1367,6 +1367,7 @@ static int arm_smmu_add_device(struct device *dev) >>>       struct arm_smmu_device *smmu; >>>       struct arm_smmu_master_cfg *cfg; >>>       struct iommu_fwspec *fwspec = dev->iommu_fwspec; >>> +    struct device_link *link; >>>       int i, ret; >>>         if (using_legacy_binding) { >>> @@ -1428,6 +1429,16 @@ static int arm_smmu_add_device(struct device *dev) >>>         pm_runtime_put_sync(smmu->dev); >>>   +    /* >>> +     * Establish the link between smmu and master, so that the >>> +     * smmu gets runtime enabled/disabled as per the master's >>> +     * needs. >>> +     */ >>> +    link = device_link_add(dev, smmu->dev, DL_FLAG_PM_RUNTIME); >>> +    if (!link) >>> +        dev_warn(smmu->dev, "Unable to create device link between %s and %s\n", >>> +             dev_name(smmu->dev), dev_name(dev)); >>> + >>>       return 0; >>>     out_cfg_free: >>> > -- "QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html