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

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Date:   Thu, 18 Jun 2020 19:49:23 +0800
From:   chao hao <Chao.Hao@...iatek.com>
To:     Matthias Brugger <matthias.bgg@...il.com>
CC:     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>,
        Yong Wu <yong.wu@...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 Wed, 2020-06-17 at 11:34 +0200, Matthias Brugger wrote:
> 
> On 17/06/2020 05:00, Chao Hao wrote:
> > Add F_MMU_IN_ORDER_WR_EN definition in MISC_CTRL.
> > In order to improve performance, we always disable STANDARD_AXI_MODE
> > and IN_ORDER_WR_EN in MISC_CTRL.
> > 
> > Change since v3:
> 
> The changelog should go below the '---' as we don't want this in the git history
> once the patch get's accepted.
> 
okok, thanks

> > 1. Rename Disable STANDARD_AXI_MODE in MISC_CTRL to Set MISC_CTRL register
> > 2. Add F_MMU_IN_DRDER_WR_EN definition in MISC_CTRL
> >        We need to disable in_order_write to improve performance
> > 
> > Cc: Yong Wu <yong.wu@...iatek.com>
> > Signed-off-by: Chao Hao <chao.hao@...iatek.com>
> > ---
> >  drivers/iommu/mtk_iommu.c | 11 +++++++++++
> >  drivers/iommu/mtk_iommu.h |  1 +
> >  2 files changed, 12 insertions(+)
> > 
> > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> > index 88d3df5b91c2..239d2cdbbc9f 100644
> > --- a/drivers/iommu/mtk_iommu.c
> > +++ b/drivers/iommu/mtk_iommu.c
> > @@ -42,6 +42,9 @@
> >  #define F_INVLD_EN1				BIT(1)
> >  
> >  #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;
> > +		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];
> >