linux-kernel - Re: [PATCH v5 06/10] iommu/mediatek: Add sub

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Message-ID: <1593515273.26985.0.camel@mbjsdccf07>
Date:   Tue, 30 Jun 2020 19:07:53 +0800
From:   chao hao <Chao.Hao@...iatek.com>
To:     Yong Wu <yong.wu@...iatek.com>
CC:     Joerg Roedel <joro@...tes.org>, Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Evan Green <evgreen@...omium.org>,
        <iommu@...ts.linux-foundation.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>, <wsd_upstream@...iatek.com>,
        FY Yang <fy.yang@...iatek.com>,
        Chao Hao <chao.hao@...iatek.com>
Subject: Re: [PATCH v5 06/10] iommu/mediatek: Add sub_comm id in translation
 fault

On Tue, 2020-06-30 at 18:55 +0800, Yong Wu wrote:
> On Mon, 2020-06-29 at 15:13 +0800, Chao Hao wrote:
> > The max larb number that a iommu HW support is 8(larb0~larb7 in the below
> > diagram).
> > If the larb's number is over 8, we use a sub_common for merging
> > several larbs into one larb. At this case, we will extend larb_id:
> > bit[11:9] means common-id;
> > bit[8:7] means subcommon-id;
> > From these two variables, we could get the real larb number when
> > translation fault happen.
> > The diagram is as below:
> > 		 EMI
> > 		  |
> > 		IOMMU
> > 		  |
> >            -----------------
> > 	   |               |
> > 	common1   	common0
> > 	   |		   |
> > 	   -----------------
> > 		  |
> >              smi common
> > 		  |
> >   ------------------------------------
> >   |       |       |       |     |    |
> >  3'd0    3'd1    3'd2    3'd3  ...  3'd7   <-common_id(max is 8)
> >   |       |       |       |     |    |
> > Larb0   Larb1     |     Larb3  ... Larb7
> > 		  |
> > 	    smi sub common
> > 		  |
> >      --------------------------
> >      |        |       |       |
> >     2'd0     2'd1    2'd2    2'd3   <-sub_common_id(max is 4)
> >      |        |       |       |
> >    Larb8    Larb9   Larb10  Larb11
> > 
> > In this patch we extend larb_remap[] to larb_remap[8][4] for this.
> > larb_remap[x][y]: x means common-id above, y means subcommon_id above.
> > 
> > We can also distinguish if the M4U HW has sub_common by HAS_SUB_COMM
> > macro.
> > 
> > Cc: Matthias Brugger <matthias.bgg@...il.com>
> > Signed-off-by: Chao Hao <chao.hao@...iatek.com>
> > Reviewed-by: Yong Wu <yong.wu@...iatek.com>
> > ---
> >  drivers/iommu/mtk_iommu.c  | 20 +++++++++++++-------
> >  drivers/iommu/mtk_iommu.h  |  3 ++-
> >  include/soc/mediatek/smi.h |  2 ++
> >  3 files changed, 17 insertions(+), 8 deletions(-)
> 
> [snip]
> 
> > @@ -48,7 +49,7 @@ struct mtk_iommu_plat_data {
> >  	enum mtk_iommu_plat m4u_plat;
> >  	u32                 flags;
> >  	u32                 inv_sel_reg;
> > -	unsigned char       larbid_remap[MTK_LARB_NR_MAX];
> > +	unsigned char       larbid_remap[MTK_LARB_COM_MAX][MTK_LARB_SUBCOM_MAX];
> >  };
> >  
> >  struct mtk_iommu_domain;
> > diff --git a/include/soc/mediatek/smi.h b/include/soc/mediatek/smi.h
> > index 5a34b87d89e3..fa65a55468e2 100644
> > --- a/include/soc/mediatek/smi.h
> > +++ b/include/soc/mediatek/smi.h
> > @@ -12,6 +12,8 @@
> >  #ifdef CONFIG_MTK_SMI
> >  
> >  #define MTK_LARB_NR_MAX		16
> > +#define MTK_LARB_COM_MAX	8
> > +#define MTK_LARB_SUBCOM_MAX	4
> 
> Both are only used in mtk_iommu.h, and I don't think smi has plan to use
> them. thus we could move them into mtk_iommu.h
> 
ok, got it. Thanks for your advice.

> >  
> >  #define MTK_SMI_MMU_EN(port)	BIT(port)
> >  
> 
>