linux-kernel - Re: [PATCH v5 03/10] iommu/mediatek: Modify the usage of mtk_iommu_plat

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Date:   Tue, 30 Jun 2020 18:56:40 +0800
From:   Yong Wu <yong.wu@...iatek.com>
To:     Chao Hao <chao.hao@...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>
Subject: Re: [PATCH v5 03/10] iommu/mediatek: Modify the usage of
 mtk_iommu_plat_data structure

Hi Chao,

This is also ok for me. Only two format nitpick.

On Mon, 2020-06-29 at 15:13 +0800, Chao Hao wrote:
> Given the fact that we are adding more and more plat_data bool values,
> it would make sense to use a u32 flags register and add the appropriate
> macro definitions to set and check for a flag present.
> No functional change.
> 
> Suggested-by: Matthias Brugger <matthias.bgg@...il.com>
> Signed-off-by: Chao Hao <chao.hao@...iatek.com>
> ---

[snip]

>  static const struct mtk_iommu_plat_data mt2712_data = {
>  	.m4u_plat     = M4U_MT2712,
> -	.has_4gb_mode = true,
> -	.has_bclk     = true,
> -	.has_vld_pa_rng   = true,
> +	.flags        = HAS_4GB_MODE |
> +			HAS_BCLK |
> +			HAS_VLD_PA_RNG,

short enough. we can put it in one line?

>  	.larbid_remap = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9},
>  };
>  
>  static const struct mtk_iommu_plat_data mt8173_data = {
>  	.m4u_plat     = M4U_MT8173,
> -	.has_4gb_mode = true,
> -	.has_bclk     = true,
> -	.reset_axi    = true,
> +	.flags	      = HAS_4GB_MODE |
> +			HAS_BCLK |
> +			RESET_AXI,
>  	.larbid_remap = {0, 1, 2, 3, 4, 5}, /* Linear mapping. */
>  };
>  
>  static const struct mtk_iommu_plat_data mt8183_data = {
>  	.m4u_plat     = M4U_MT8183,
> -	.reset_axi    = true,
> +	.flags        = RESET_AXI,
>  	.larbid_remap = {0, 4, 5, 6, 7, 2, 3, 1},
>  };
>  
> diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h
> index 1b6ea839b92c..7cc39f729263 100644
> --- a/drivers/iommu/mtk_iommu.h
> +++ b/drivers/iommu/mtk_iommu.h
> @@ -17,6 +17,15 @@
>  #include <linux/spinlock.h>
>  #include <soc/mediatek/smi.h>
>  
> +#define HAS_4GB_MODE			BIT(0)
> +/* HW will use the EMI clock if there isn't the "bclk". */
> +#define HAS_BCLK			BIT(1)
> +#define HAS_VLD_PA_RNG			BIT(2)
> +#define RESET_AXI			BIT(3)
> +
> +#define MTK_IOMMU_HAS_FLAG(pdata, _x) \
> +		((((pdata)->flags) & (_x)) == (_x))

If these definitions are not used in mtk_iommu_v1.c(also no this plan),
then we can put them in the mtk_iommu.c.


BTW, the patch title "modify the usage of mtk_iommu_plat_data structure"
isn't so clear, we could write what the detailed modification is.
something like:
iommu/mediatek: Use a u32 flags to describe different HW features

> +
>  struct mtk_iommu_suspend_reg {
>  	u32				misc_ctrl;
>  	u32				dcm_dis;
> @@ -36,12 +45,7 @@ enum mtk_iommu_plat {
>  
>  struct mtk_iommu_plat_data {
>  	enum mtk_iommu_plat m4u_plat;
> -	bool                has_4gb_mode;
> -
> -	/* HW will use the EMI clock if there isn't the "bclk". */
> -	bool                has_bclk;
> -	bool                has_vld_pa_rng;
> -	bool                reset_axi;
> +	u32                 flags;
>  	unsigned char       larbid_remap[MTK_LARB_NR_MAX];
>  };
>