From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-wm0-f68.google.com ([74.125.82.68]:33666 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752734AbeDETLz (ORCPT ); Thu, 5 Apr 2018 15:11:55 -0400 Received: by mail-wm0-f68.google.com with SMTP id o23so4722096wmf.0 for ; Thu, 05 Apr 2018 12:11:54 -0700 (PDT) Subject: Re: [PATCH net-next v2 2/2] dt: bindings: add new dt entries for brcmfmac To: Kalle Valo , Ulf Hansson References: <20180319014032.9394-1-alexey.roslyakov@gmail.com> <20180319014032.9394-3-alexey.roslyakov@gmail.com> <5AAF838D.2030105@broadcom.com> <817418fd-6446-57ea-b03d-383b4df9a979@gmail.com> <5AB044C0.9060701@broadcom.com> <87po3zxe9n.fsf@kamboji.qca.qualcomm.com> <87lge1er31.fsf@kamboji.qca.qualcomm.com> Cc: Florian Fainelli , Alexey Roslyakov , Andrew Lunn , Rob Herring , Mark Rutland , Franky Lin , Hante Meuleman , Chi-Hsien Lin , Wright Feng , netdev@vger.kernel.org, linux-wireless@vger.kernel.org, devicetree@vger.kernel.org, Linux Kernel Mailing List , brcm80211-dev-list.pdl@broadcom.com, brcm80211-dev-list@cypress.com From: Arend van Spriel Message-ID: <5AC674F8.7080100@broadcom.com> (sfid-20180405_211211_145312_EFF1D609) Date: Thu, 5 Apr 2018 21:11:52 +0200 MIME-Version: 1.0 In-Reply-To: <87lge1er31.fsf@kamboji.qca.qualcomm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 4/5/2018 3:10 PM, Kalle Valo wrote: > Ulf Hansson writes: > >> On 20 March 2018 at 10:55, Kalle Valo wrote: >>> Arend van Spriel writes: >>> >>>>>> If I get it right, you mean something like this: >>>>>> >>>>>> mmc3: mmc@1c12000 { >>>>>> ... >>>>>> broken-sg-support; >>>>>> sd-head-align = 4; >>>>>> sd-sgentry-align = 512; >>>>>> >>>>>> brcmf: wifi@1 { >>>>>> ... >>>>>> }; >>>>>> }; >>>>>> >>>>>> Where dt: bindings documentation for these entries should reside? >>>>>> In generic MMC bindings? Well, this is the very special case and >>>>>> mmc-linux maintainer will unlikely to accept these changes. >>>>>> Also, extra kernel code modification might be required. It could make >>>>>> quite trivial change much more complex. >>>>> >>>>> If the MMC maintainers are not copied on this patch series, it will >>>>> likely be hard for them to identify this patch series and chime in... >>>> >>>> The main question is whether this is indeed a "very special case" as >>>> Alexey claims it to be or that it is likely to be applicable to other >>>> device and host combinations as you are suggesting. >>>> >>>> If these properties are imposed by the host or host controller it >>>> would make sense to have these in the mmc bindings. >>> >>> BTW, last year we were discussing something similar (I mean related to >>> alignment requirements) with ath10k SDIO patches and at the time the >>> patch submitter was proposing to have a bounce buffer in ath10k to >>> workaround that. I don't remember the details anymore, they are on the >>> ath10k mailing list archive if anyone is curious to know, but I would >>> not be surprised if they are similar as here. So there might be a need >>> to solve this in a generic way (but not sure of course as I haven't >>> checked the details). >> >> I re-call something about these as well, here are the patches. Perhaps >> I should pick some of them up... >> >> https://patchwork.kernel.org/patch/10123137/ >> https://patchwork.kernel.org/patch/10123139/ >> https://patchwork.kernel.org/patch/10123141/ >> https://patchwork.kernel.org/patch/10123143/ > > Actually I was talking about a different patch, found it now: > > ath10k_sdio: DMA bounce buffers for read write > > https://patchwork.kernel.org/patch/9979543/ The patches Uffe mentions are related to this. In brcmfmac we simply implemented functionality to create a scatter list and send it through the MMC stack using SDIO CMD53. It is in the creation of the scatter list that these alignment properties are needed. Moving the whole functionality to the MMC stack will also move those properties into their right context, ie. SDIO host controller. Our broker_sg_support property is basically doing the bounce buffer thing if I understand it correctly. Regards, Arend