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From:   Evan Green <evgreen@chromium.org>
Date:   Wed, 30 Jan 2019 11:07:13 -0800
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Subject: Re: [PATCH v5 16/20] memory: mtk-smi: Add bus_sel for mt8183
To:     Yong Wu <yong.wu@mediatek.com>
Cc:     Joerg Roedel <joro@8bytes.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Rob Herring <robh+dt@kernel.org>,
        Tomasz Figa <tfiga@google.com>,
        Will Deacon <will.deacon@arm.com>,
        linux-mediatek@lists.infradead.org, srv_heupstream@mediatek.com,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        iommu@lists.linux-foundation.org, Arnd Bergmann <arnd@arndb.de>,
        yingjoe.chen@mediatek.com, youlin.pei@mediatek.com,
        Nicolas Boichat <drinkcat@chromium.org>
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On Mon, Dec 31, 2018 at 7:59 PM Yong Wu <yong.wu@mediatek.com> wrote:
>
> There are 2 mmu cells in a M4U HW. we could adjust some larbs entering
> mmu0 or mmu1 to balance the bandwidth via the smi-common register
> SMI_BUS_SEL(0x220)(Each larb occupy 2 bits).
>
> In mt8183, For better performance, we switch larb1/2/5/7 to enter
> mmu1 while the others still keep enter mmu0.
>
> In mt8173 and mt2712, we don't get the performance issue,
> Keep its default value(0x0), that means all the larbs enter mmu0.
>
> Note: smi gen1(mt2701/mt7623) don't have this bus_sel.
>
> CC: Matthias Brugger <matthias.bgg@gmail.com>
> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> ---
>  drivers/memory/mtk-smi.c | 22 ++++++++++++++++++++--
>  1 file changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/memory/mtk-smi.c b/drivers/memory/mtk-smi.c
> index 9790801..08cf40d 100644
> --- a/drivers/memory/mtk-smi.c
> +++ b/drivers/memory/mtk-smi.c
> @@ -49,6 +49,12 @@
>  #define SMI_LARB_NONSEC_CON(id)        (0x380 + ((id) * 4))
>  #define F_MMU_EN               BIT(0)
>
> +/* SMI COMMON */
> +#define SMI_BUS_SEL                    0x220
> +#define SMI_BUS_LARB_SHIFT(larbid)     ((larbid) << 1)
> +/* All are MMU0 defaultly. Only specialize mmu1 here. */
> +#define F_MMU1_LARB(larbid)            (0x1 << SMI_BUS_LARB_SHIFT(larbid))
> +
>  enum mtk_smi_gen {
>         MTK_SMI_GEN1,
>         MTK_SMI_GEN2
> @@ -57,6 +63,7 @@ enum mtk_smi_gen {
>  struct mtk_smi_common_plat {
>         enum mtk_smi_gen gen;
>         bool             has_gals;
> +       u32              bus_sel; /* Balance some larbs to enter mmu0 or mmu1 */
>  };
>
>  struct mtk_smi_larb_gen {
> @@ -72,8 +79,8 @@ struct mtk_smi {
>         struct clk                      *clk_apb, *clk_smi;
>         struct clk                      *clk_gals0, *clk_gals1;
>         struct clk                      *clk_async; /*only needed by mt2701*/
> -       void __iomem                    *smi_ao_base;
> -
> +       void __iomem                    *smi_ao_base; /* only for gen1 */
> +       void __iomem                    *base;        /* only for gen2 */
>         const struct mtk_smi_common_plat *plat;
>  };
>
> @@ -410,6 +417,8 @@ static int __maybe_unused mtk_smi_larb_suspend(struct device *dev)
>  static const struct mtk_smi_common_plat mtk_smi_common_mt8183 = {
>         .gen      = MTK_SMI_GEN2,
>         .has_gals = true,
> +       .bus_sel  = F_MMU1_LARB(1) | F_MMU1_LARB(2) | F_MMU1_LARB(5) |
> +                   F_MMU1_LARB(7),
>  };
>
>  static const struct of_device_id mtk_smi_common_of_ids[] = {
> @@ -482,6 +491,11 @@ static int mtk_smi_common_probe(struct platform_device *pdev)
>                 ret = clk_prepare_enable(common->clk_async);
>                 if (ret)
>                         return ret;
> +       } else {
> +               res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +               common->base = devm_ioremap_resource(dev, res);
> +               if (IS_ERR(common->base))
> +                       return PTR_ERR(common->base);

So you split base and smi_ao_base because they're completely different
register regions, or because ->base is no longer "always on"? It's
tempting to recombine them because they appear to be mutually
exclusive, but if they're truly different register regions then I
understand.