linux-kernel - Re: [PATCH v4 3/7] iommu/mediatek: Set MISC

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Message-ID: <1592980794.24677.4.camel@mbjsdccf07>
Date:   Wed, 24 Jun 2020 14:39:54 +0800
From:   chao hao <Chao.Hao@...iatek.com>
To:     Yong Wu <yong.wu@...iatek.com>
CC:     Matthias Brugger <matthias.bgg@...il.com>,
        Joerg Roedel <joro@...tes.org>,
        Rob Herring <robh+dt@...nel.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 v4 3/7] iommu/mediatek: Set MISC_CTRL register

On Sat, 2020-06-20 at 10:03 +0800, Yong Wu wrote:
> Hi Chao,
> 
> On Thu, 2020-06-18 at 19:49 +0800, chao hao wrote: 
> > On Wed, 2020-06-17 at 11:34 +0200, Matthias Brugger wrote:
> 
> [snip]
> 
> > > >  
> > > >  #define REG_MMU_MISC_CTRL			0x048
> > > > +#define F_MMU_IN_ORDER_WR_EN			(BIT(1) | BIT(17))
> > > > +#define F_MMU_STANDARD_AXI_MODE_BIT		(BIT(3) | BIT(19))
> > > > +
> > > >  #define REG_MMU_DCM_DIS				0x050
> > > >  
> > > >  #define REG_MMU_CTRL_REG			0x110
> > > > @@ -578,6 +581,14 @@ static int mtk_iommu_hw_init(const struct mtk_iommu_data *data)
> > > >  		writel_relaxed(0, data->base + REG_MMU_MISC_CTRL);
> > > >  	}
> > > >  
> > > > +	if (data->plat_data->has_misc_ctrl) {
> > > 
> > > That's confusing. We renamed the register to misc_ctrl, but it's present in all
> > > SoCs. We should find a better name for this flag to describe what the hardware
> > > supports.
> > > 
> > 
> > ok, thanks for you advice, I will rename it in next version.
> > ex:has_perf_req(has performance requirement)
> > 
> > 
> > > Regards,
> > > Matthias
> > > 
> > > > +		/* For mm_iommu, it can improve performance by the setting */
> > > > +		regval = readl_relaxed(data->base + REG_MMU_MISC_CTRL);
> > > > +		regval &= ~F_MMU_STANDARD_AXI_MODE_BIT;
> > > > +		regval &= ~F_MMU_IN_ORDER_WR_EN;
> 
> Note: mt2712 also is MISC_CTRL register, but it don't use this
> in_order setting.
> 
> As commented in v3. 0x48 is either STANDARD_AXI_MODE or MISC_CTRL
> register. No need two flags(reset_axi/has_xx) for it.
> 
> something like:
> 
> regval = readl_relaxed(data->base + REG_MMU_MISC_CTRL);
> if (reset_axi) {
> regval = 0;
> } else {   /* MISC_CTRL */
> if (!apu[1])
> regval &= ~F_MMU_STANDARD_AXI_MODE_BIT;
> if (out_order_en)
> regval &= ~F_MMU_IN_ORDER_WR_EN;
> }
> writel_relaxed(regval, data->base + REG_MMU_MISC_CTRL);
> 
> 
> [1] Your current patch doesn't support apu-iommu, thus, add it when
> necessary.

ok, the patchset don't need to "if (!apu[1])", I will fix it in next
version. thanks


> > > > +		writel_relaxed(regval, data->base + REG_MMU_MISC_CTRL);
> > > > +	}
> > > > +
> > > >  	if (devm_request_irq(data->dev, data->irq, mtk_iommu_isr, 0,
> > > >  			     dev_name(data->dev), (void *)data)) {
> > > >  		writel_relaxed(0, data->base + REG_MMU_PT_BASE_ADDR);
> > > > diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h
> > > > index 1b6ea839b92c..d711ac630037 100644
> > > > --- a/drivers/iommu/mtk_iommu.h
> > > > +++ b/drivers/iommu/mtk_iommu.h
> > > > @@ -40,6 +40,7 @@ struct mtk_iommu_plat_data {
> > > >  
> > > >  	/* HW will use the EMI clock if there isn't the "bclk". */
> > > >  	bool                has_bclk;
> > > > +	bool		    has_misc_ctrl;
> > > >  	bool                has_vld_pa_rng;
> > > >  	bool                reset_axi;
> > > >  	unsigned char       larbid_remap[MTK_LARB_NR_MAX];
> > > > 
> > 
> > 
>