From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8DCFC433FE for ; Wed, 18 May 2022 01:13:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233310AbiERBNg (ORCPT ); Tue, 17 May 2022 21:13:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44808 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229736AbiERBNe (ORCPT ); Tue, 17 May 2022 21:13:34 -0400 Received: from mailgw02.mediatek.com (unknown [210.61.82.184]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C5A951E4C; Tue, 17 May 2022 18:13:28 -0700 (PDT) X-UUID: 0a14b6a7b94e48adb474547db5e70b92-20220518 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.5,REQID:e0c1e221-3d54-4bdd-a806-4867722f3970,OB:0,LO B:0,IP:0,URL:0,TC:0,Content:0,EDM:0,RT:0,SF:0,FILE:0,RULE:Release_Ham,ACTI ON:release,TS:0 X-CID-META: VersionHash:2a19b09,CLOUDID:389f8ce2-edbf-4bd4-8a34-dfc5f7bb086d,C OID:IGNORED,Recheck:0,SF:nil,TC:nil,Content:0,EDM:-3,IP:nil,URL:1,File:nil ,QS:0,BEC:nil X-UUID: 0a14b6a7b94e48adb474547db5e70b92-20220518 Received: from mtkexhb02.mediatek.inc [(172.21.101.103)] by mailgw02.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 948408978; Wed, 18 May 2022 09:13:23 +0800 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkmbs11n2.mediatek.inc (172.21.101.187) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.792.3; Wed, 18 May 2022 09:13:21 +0800 Received: from mhfsdcap04 (10.17.3.154) by mtkcas11.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Wed, 18 May 2022 09:13:20 +0800 Message-ID: <1614c81e4975c5cfd19c8090d523b16116907389.camel@mediatek.com> Subject: Re: [PATCH 2/2] iommu: mtk_iommu: Add support for MT6795 Helio X10 M4Us From: Yong Wu To: AngeloGioacchino Del Regno CC: , , , , , , , , , , , , , <~postmarketos/upstreaming@lists.sr.ht>, , , , , , Date: Wed, 18 May 2022 09:13:20 +0800 In-Reply-To: <9a67d3e8-8840-03b1-aec8-5a218e810eae@collabora.com> References: <20220513151411.395744-1-angelogioacchino.delregno@collabora.com> <20220513151411.395744-3-angelogioacchino.delregno@collabora.com> <38e38006662b52631a2145228444b9d70f9eb2c6.camel@mediatek.com> <9a67d3e8-8840-03b1-aec8-5a218e810eae@collabora.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2022-05-17 at 11:26 +0200, AngeloGioacchino Del Regno wrote: > Il 17/05/22 11:08, Yong Wu ha scritto: > > On Fri, 2022-05-13 at 17:14 +0200, AngeloGioacchino Del Regno > > wrote: > > > Add support for the M4Us found in the MT6795 Helio X10 SoC. > > > > > > Signed-off-by: AngeloGioacchino Del Regno < > > > angelogioacchino.delregno@collabora.com> > > > --- > > > drivers/iommu/mtk_iommu.c | 20 +++++++++++++++++++- > > > 1 file changed, 19 insertions(+), 1 deletion(-) [...] > > > +static const struct mtk_iommu_plat_data mt6795_data = { > > > + .m4u_plat = M4U_MT6795, > > > + .flags = HAS_4GB_MODE | HAS_BCLK | RESET_AXI | > > > + HAS_LEGACY_IVRP_PADDR | MTK_IOMMU_TYPE_MM, > > > + .inv_sel_reg = REG_MMU_INV_SEL_GEN1, > > > + .banks_num = 1, > > > + .banks_enable = {true}, > > > + .iova_region = single_domain, > > > + .iova_region_nr = ARRAY_SIZE(single_domain), > > > + .larbid_remap = {{0}, {1}, {2}, {3}, {4}}, /* Linear mapping. > > > */ > > > +}; > > > > This is nearly same with mt8173_data. mt8173 has one more larb than > > mt6795, its larbid_remap is also ok for mt6795. > > > > I think that we should be explicit about the larbid_remap property, > since mt6795 has one less larb, we should explicitly say that like > I did there... that's only for human readability I admit ... but, > still, I wouldn't want to see people thinking that MT6795 has 6 LARBs > because they've read that larbid_remap having 6 entries. In the linear mapping case, It does help. Strictly larbid_remap is two- dimensional array now, It doesn't indicate how many larbs this SoC has. If someone would like to know this, he could read the mtxxx-larb- port.h. We also could document the larb numbers in the binding for readability. Anyway, It is not a big problem. A new structure is ok for me. I just complain there are too many structures, specially in the internal branch which contains many non-upstream SoCs, and there may be several IOMMU HWs in one SoC. thus I'd like to group it personally. > > > thus it looks we could use mt8173 as the backward compatible. > > compatible = "mediatek,mt6795-m4u", > > "mediatek,mt8173-m4u"; > > > > After this, the only thing is about "mediatek,mt6795-infracfg". we > > have > > to try again with mediatek,mt6795-infracfg after mediatek,mt8173- > > infracfg fail. I think we should allow the backward case in 4GB > > mode > > judgment if we have. > > > > What's your opinion? or some other suggestion? > > Thanks. > > I know, I may have a plan for that, but I wanted to have a good > reason to > propose such a thing, as if it's just about two SoCs needing that, > there > would be no good reason to get things done differently. > > ...so, in order to provide a good cleanup, we have two possible roads > to > follow here: either we add a generic "mediatek,infracfg" compatible > to the > infra node (but I don't like that), or we can do it like it was > previously > done in mtk-pm-domains.c (I prefer that approach): > > iommu: iommu@somewhere { > ... something ... > mediatek,infracfg = <&infracfg>; We like this too. But this was not suggested from Rob long before. https://lore.kernel.org/linux-mediatek/20200715205120.GA778876@bogus/ > }; > > infracfg = syscon_regmap_lookup_by_compatible(node, > "mediatek,infracfg"); > if (IS_ERR(infracfg)) { > /* try with the older way */ > switch (...) { > case .... p = "mediatek,mt2712-infracfg"; > ... blah blah ... > } > /* legacy also failed, ouch! */ > if (IS_ERR(infracfg)) > return PTR_ERR(infracfg); > } > > ret = regmap_read ... etc etc etc > > Cheers, > Angelo