From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Gautam Subject: Re: [PATCH v12 3/4] iommu/arm-smmu: Add the device_link between masters and smmu Date: Tue, 17 Jul 2018 14:00:29 +0530 Message-ID: References: <20180708173413.1965-1-vivek.gautam@codeaurora.org> <20180708173413.1965-4-vivek.gautam@codeaurora.org> <5179668.PHK6S3sxLu@aspire.rjw.lan> <741cc78b-59a7-5289-e42f-1511ebedb15d@codeaurora.org> <93d16301-4bef-203f-24de-4d010de84b22@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; Format="flowed" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: freedreno-bounces-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org Sender: "Freedreno" To: "Rafael J. Wysocki" Cc: Mark Rutland , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Archit Taneja , Jordan Crouse , Alex Williamson , Linux PM , Stephen Boyd , Will Deacon , Joerg Roedel , "Rafael J. Wysocki" , open list , Tomasz Figa , "list-Y9sIeH5OGRo@public.gmane.org:IOMMU DRIVERS" , robh+dt , Rob Clark , linux-arm-msm , Sricharan R , freedreno , Robin Murphy , Lukas Wunner , Marek Szyprowski List-Id: linux-arm-msm@vger.kernel.org CgpPbiA3LzE3LzIwMTggMToxNiBQTSwgUmFmYWVsIEouIFd5c29ja2kgd3JvdGU6Cj4gT24gTW9u LCBKdWwgMTYsIDIwMTggYXQgMTo0NiBQTSwgVml2ZWsgR2F1dGFtCj4gPHZpdmVrLmdhdXRhbUBj b2RlYXVyb3JhLm9yZz4gd3JvdGU6Cj4+Cj4+IE9uIDcvMTYvMjAxOCAyOjI1IFBNLCBSYWZhZWwg Si4gV3lzb2NraSB3cm90ZToKPj4+IE9uIFRodSwgSnVsIDEyLCAyMDE4IGF0IDI6NDEgUE0sIFZp dmVrIEdhdXRhbQo+Pj4gPHZpdmVrLmdhdXRhbUBjb2RlYXVyb3JhLm9yZz4gd3JvdGU6Cj4+Pj4g SGkgUmFmYWVsLAo+Pj4+Cj4+Pj4KPj4+PiBPbiBXZWQsIEp1bCAxMSwgMjAxOCBhdCA0OjA2IFBN LCBWaXZlayBHYXV0YW0KPj4+PiA8dml2ZWsuZ2F1dGFtQGNvZGVhdXJvcmEub3JnPiB3cm90ZToK Pj4+Pj4gSGkgUmFmYWVsLAo+Pj4+Pgo+Pj4+Pgo+Pj4+Pgo+Pj4+PiBPbiA3LzExLzIwMTggMzoy MyBQTSwgUmFmYWVsIEouIFd5c29ja2kgd3JvdGU6Cj4+Pj4+PiBPbiBTdW5kYXksIEp1bHkgOCwg 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d=codeaurora.org; s=default; t=1531816237; bh=x9Bt6mETE0lSDv3O6sBnD/A2P9/1BYs479Of81kPsjY=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=hAjgHdWw9/bQlyNpmBrhHhNT+WBIN/4sWW45P/ae5C+gQ5+5N6gl5tUhT9LEbbpRu eiqXad2b6jR7TaXBIsh/0Osb8yQKEZXAEUDYgnJra3zYzua0soh44Zx9sU3q+tQjUk 4qbQsF64/Xpnb1zK9Y8qzZxUHmkwDZgNRD+NWDH0= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 95C796060A Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=vivek.gautam@codeaurora.org Subject: Re: [PATCH v12 3/4] iommu/arm-smmu: Add the device_link between masters and smmu To: "Rafael J. Wysocki" Cc: "Rafael J. Wysocki" , "list@263.net:IOMMU DRIVERS" , Joerg Roedel , robh+dt , Mark Rutland , Robin Murphy , Will Deacon , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , open list , Alex Williamson , Rob Clark , Linux PM , freedreno , Stephen Boyd , Tomasz Figa , Sricharan R , Marek Szyprowski , Archit Taneja , linux-arm-msm , Jordan Crouse , Lukas Wunner References: <20180708173413.1965-1-vivek.gautam@codeaurora.org> <20180708173413.1965-4-vivek.gautam@codeaurora.org> <5179668.PHK6S3sxLu@aspire.rjw.lan> <741cc78b-59a7-5289-e42f-1511ebedb15d@codeaurora.org> <93d16301-4bef-203f-24de-4d010de84b22@codeaurora.org> From: Vivek Gautam Message-ID: Date: Tue, 17 Jul 2018 14:00:29 +0530 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/17/2018 1:16 PM, Rafael J. Wysocki wrote: > On Mon, Jul 16, 2018 at 1:46 PM, Vivek Gautam > wrote: >> >> On 7/16/2018 2:25 PM, Rafael J. Wysocki wrote: >>> On Thu, Jul 12, 2018 at 2:41 PM, Vivek Gautam >>> wrote: >>>> Hi Rafael, >>>> >>>> >>>> On Wed, Jul 11, 2018 at 4:06 PM, Vivek Gautam >>>> wrote: >>>>> Hi Rafael, >>>>> >>>>> >>>>> >>>>> On 7/11/2018 3:23 PM, Rafael J. Wysocki wrote: >>>>>> On Sunday, July 8, 2018 7:34:12 PM CEST 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 >>>>>>> Reviewed-by: Tomasz Figa >>>>>>> Cc: Rafael J. Wysocki >>>>>>> Cc: Lukas Wunner >>>>>>> --- >>>>>>> >>>>>>> - Change since v11 >>>>>>> * Replaced DL_FLAG_AUTOREMOVE flag with >>>>>>> DL_FLAG_AUTOREMOVE_SUPPLIER. >>>>>>> >>>>>>> drivers/iommu/arm-smmu.c | 12 ++++++++++++ >>>>>>> 1 file changed, 12 insertions(+) >>>>>>> >>>>>>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c >>>>>>> index 09265e206e2d..916cde4954d2 100644 >>>>>>> --- a/drivers/iommu/arm-smmu.c >>>>>>> +++ b/drivers/iommu/arm-smmu.c >>>>>>> @@ -1461,8 +1461,20 @@ static int arm_smmu_add_device(struct device >>>>>>> *dev) >>>>>>> iommu_device_link(&smmu->iommu, dev); >>>>>>> + if (pm_runtime_enabled(smmu->dev) && >>>>>> Why does the creation of the link depend on whether or not runtime PM >>>>>> is enabled for the MMU device? >>>>> >>>>> The main purpose of this device link is to handle the runtime PM >>>>> synchronization >>>>> between the supplier (iommu) and consumer (client devices, such as >>>>> GPU/display). >>>>> Moreover, the runtime pm is conditionally enabled for smmu devices that >>>>> support >>>>> such [1]. >>>> Is there something you would like me to modify in this patch? >>> Not really, as long as you are sure that it is correct. :-) >>> >>> You need to remember, however, that if you add system-wide PM >>> callbacks to the driver, the ordering between them and the client >>> device callbacks during system-wide suspend matters as well. Don't >>> you need the link the ensure the correct system-wide suspend ordering >>> too? >> >> The fact that currently we handle clocks only through runtime pm callbacks, >> would it be better to call runtime pm put/get in system-wide PM callbacks. >> This would be same as i mentioned in the other thread. > Well, my point is that there's no reason for system-wide suspend to > depend directly on runtime PM (which can be effectively disabled by > user space as mentioned for multiple times in this thread). > > It simply is not efficient to let the clock run while the system as a > whole is sleeping (even if power/control has been set to "on" for this > particular device) and it should not be too hard to prevent that from > happening. You may need an additional flag in the driver for that or > similar, but it definitely should be doable. Right, I will modify the things are required. Thanks again for pointing this out. Best regards Vivek > > Now, that's my advice and I'm not the maintainer of that code, so it > is your call (as long as the maintainer agrees with it). > > Thanks, > Rafael