From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932108AbcGBQgj (ORCPT ); Sat, 2 Jul 2016 12:36:39 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:33340 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752162AbcGBQgi (ORCPT ); Sat, 2 Jul 2016 12:36:38 -0400 Subject: Re: [PATCH v7 2/4] soc: mediatek: Init MT8173 scpsys driver earlier To: James Liao , Sascha Hauer References: <1463390894-32062-1-git-send-email-jamesjj.liao@mediatek.com> <1463390894-32062-3-git-send-email-jamesjj.liao@mediatek.com> Cc: Rob Herring , Kevin Hilman , Daniel Kurtz , srv_heupstream@mediatek.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org From: Matthias Brugger Message-ID: <34025ec4-19d3-8b25-d669-50c6f19159cd@gmail.com> Date: Sat, 2 Jul 2016 18:35:41 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 MIME-Version: 1.0 In-Reply-To: <1463390894-32062-3-git-send-email-jamesjj.liao@mediatek.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/16/2016 11:28 AM, James Liao wrote: > Some power domain comsumers may init before module_init. > So the power domain provider (scpsys) need to be initialized > earlier too. > > Take an example for our IOMMU (M4U) and SMI. SMI is a bridge > between IOMMU and multimedia HW. SMI is responsible to > enable/disable iommu and help transfer data for each multimedia > HW. Both of them have to wait until the power and clocks are > enabled. > > So scpsys driver should be initialized before SMI, and SMI should > be initialized before IOMMU, and then init IOMMU consumers > (display/vdec/venc/camera etc.). > > IOMMU is subsys_init by default. So we need to init scpsys driver > before subsys_init. > > Signed-off-by: James Liao > Reviewed-by: Kevin Hilman > --- > drivers/soc/mediatek/mtk-scpsys.c | 19 ++++++++++++++++++- > 1 file changed, 18 insertions(+), 1 deletion(-) > > diff --git a/drivers/soc/mediatek/mtk-scpsys.c b/drivers/soc/mediatek/mtk-scpsys.c > index 5870a24..00c0adb 100644 > --- a/drivers/soc/mediatek/mtk-scpsys.c > +++ b/drivers/soc/mediatek/mtk-scpsys.c > @@ -617,4 +617,21 @@ static struct platform_driver scpsys_drv = { > .of_match_table = of_match_ptr(of_scpsys_match_tbl), > }, > }; > -builtin_platform_driver(scpsys_drv); > + > +static int __init scpsys_drv_init(void) > +{ > + return platform_driver_register(&scpsys_drv); > +} > + > +/* > + * There are some Mediatek drivers which depend on the power domain driver need > + * to probe in earlier initcall levels. So scpsys driver also need to probe > + * earlier. > + * > + * IOMMU(M4U) and SMI drivers for example. SMI is a bridge between IOMMU and > + * multimedia HW. IOMMU depends on SMI, and SMI is a power domain consumer, > + * so the proper probe sequence should be scpsys -> SMI -> IOMMU driver. > + * IOMMU drivers are initialized during subsys_init by default, so we need to > + * move SMI and scpsys drivers to subsys_init or earlier init levels. > + */ > +subsys_initcall(scpsys_drv_init); > Can't we achieve this with probe deferring? I'm not really keen on coding the order of the different drivers like this. Regards, Matthias