From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Gautam Subject: Re: [PATCH v8 4/5] iommu/arm-smmu: Add the device_link between masters and smmu Date: Mon, 12 Mar 2018 15:51:44 +0530 Message-ID: References: <20180302101050.6191-1-vivek.gautam@codeaurora.org> <20180302101050.6191-5-vivek.gautam@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: 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: Robin Murphy Cc: Mark Rutland , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "Rafael J. Wysocki" , Will Deacon , open list , "list-Y9sIeH5OGRo@public.gmane.org:IOMMU DRIVERS" , robh+dt , linux-arm-msm , Stephen Boyd List-Id: linux-arm-msm@vger.kernel.org On Fri, Mar 9, 2018 at 6:04 PM, Robin Murphy wrote: > On 09/03/18 07:11, Vivek Gautam wrote: >> >> On Thu, Mar 8, 2018 at 10:29 AM, Vivek Gautam >> wrote: >>> >>> On Wed, Mar 7, 2018 at 6:17 PM, Robin Murphy >>> wrote: >>>> >>>> On 02/03/18 10:10, 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. >>>>> >>>>> Signed-off-by: Sricharan R >>>>> Signed-off-by: Vivek Gautam >>>>> --- >>>>> drivers/iommu/arm-smmu.c | 21 +++++++++++++++++++++ >>>>> 1 file changed, 21 insertions(+) >>>>> >>>>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c >>>>> index 3d6a1875431f..bb1ea82c1003 100644 >>>>> --- a/drivers/iommu/arm-smmu.c >>>>> +++ b/drivers/iommu/arm-smmu.c >>>>> @@ -217,6 +217,9 @@ struct arm_smmu_device { >>>>> /* IOMMU core code handle */ >>>>> struct iommu_device iommu; >>>>> + >>>>> + /* runtime PM link to master */ >>>>> + struct device_link *link; >>>> >>>> >>>> >>>> Just the one? >> >> >> we will either have to count all the devices that are present on the >> iommu bus, or >> maintain a list to which all the links can be added. >> But to add the list, we will have to initialize a LIST_HEAD in struct >> device_link >> as well. >> >> Or, I think we don't even need to maintain a pointer to link with smmu. >> In arm_smmu_remove_device(), we can find out the correct link, and delete >> it. >> >> list_for_each_entry(link, &dev->links.suppliers, c_node) >> if (link->supplier == smmu->dev); >> device_link_del(link); >> >> Should that be fine? >> >> Rafael, does the above snippet looks right to you? Context: smmu->dev >> is the supplier, and dev is the consumer. We want to find the link, >> and delete it. > > > Actually, looking at the existing code, it seems like device_link_add() will > in fact look up and return any existing link between a given supplier and > consumer - is that intentional API behaviour that users may rely on to avoid > keeping track of explicit link pointers? > (or conversely, might it be > reasonable to factor out a device_link_find() function?) Yea, that sounds better. regards Vivek > > Robin. > > -- > To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation