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    SubjectRe: [PATCH v4 2/2] soc: mediatek: add mtk-devapc driver
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    On Tue, 2020-08-04 at 00:04 +0800, Chun-Kuang Hu wrote:
    > Hi, Neal:
    >
    > Neal Liu <neal.liu@mediatek.com> 於 2020年8月3日 週一 下午12:01寫道:
    > >
    > > Hi Chun-Kuang,
    > >
    > > On Sat, 2020-08-01 at 08:12 +0800, Chun-Kuang Hu wrote:
    > > > Hi, Neal:
    > > >
    > > > This patch is for "mediatek,mt6779-devapc", so I think commit title
    > > > should show the SoC ID.
    > >
    > > Okay, I'll change title to 'soc:mediatek: add mt6779 devapc driver'.
    > >
    > > >
    > > > Neal Liu <neal.liu@mediatek.com> 於 2020年7月29日 週三 下午4:29寫道:
    > > > >
    > > > > MediaTek bus fabric provides TrustZone security support and data
    > > > > protection to prevent slaves from being accessed by unexpected
    > > > > masters.
    > > > > The security violation is logged and sent to the processor for
    > > > > further analysis or countermeasures.
    > > > >
    > > > > Any occurrence of security violation would raise an interrupt, and
    > > > > it will be handled by mtk-devapc driver. The violation
    > > > > information is printed in order to find the murderer.
    > > > >
    > > > > Signed-off-by: Neal Liu <neal.liu@mediatek.com>
    > > > > ---
    > > >
    > > > [snip]
    > > >
    > > > > +
    > > > > +struct mtk_devapc_context {
    > > > > + struct device *dev;
    > > > > + u32 vio_idx_num;
    > > > > + void __iomem *devapc_pd_base;
    > > > > + struct mtk_devapc_vio_info *vio_info;
    > > > > + const struct mtk_devapc_pd_offset *offset;
    > > > > + const struct mtk_devapc_vio_dbgs *vio_dbgs;
    > > > > +};
    > > >
    > > > I think this structure should separate the constant part. The constant part is:
    > > >
    > > > struct mtk_devapc_data {
    > > > const u32 vio_idx_num;
    > > > const struct mtk_devapc_pd_offset *offset; /* I would like to
    > > > remove struct mtk_devapc_pd_offset and directly put its member into
    > > > this structure */
    > > > const struct mtk_devapc_vio_dbgs *vio_dbgs; /* This may disappear */
    > > > };
    > > >
    > > > And the context is:
    > > >
    > > > struct mtk_devapc_context {
    > > > struct device *dev;
    > > > void __iomem *devapc_pd_base;
    > > > const struct mtk_devapc_data *data;
    > > > };
    > > >
    > > > So when you define this, you would not waste memory to store non-constant data.
    > > >
    > > > static const struct mtk_devapc_data devapc_mt6779 = {
    > > > .vio_idx_num = 510,
    > > > .offset = &mt6779_pd_offset,
    > > > .vio_dbgs = &mt6779_vio_dbgs,
    > > > };
    > > >
    > >
    > > Sorry, I still don't understand why this refactoring will not waste
    > > memory to store non-constant data. Could you explain more details?
    > > To my understanding, we still also have to allocate memory to store dev
    > > & devapc_pd_base.
    >
    > In some situation, it is. You make the non-constant data a global
    > variable. I think the context data should be dynamic allocated. If
    > this driver is not probed, the non-constant data occupy the memory.
    >

    I got your point! In this case, we can save these 2 data structure
    space, right?

    struct device *dev;
    void __iomem *devapc_pd_base;

    I'll refactoring this data structures on next patch. Thanks !

    > Regards,
    > Chun-Kuang.
    >
    > >
    > > > Regards,
    > > > Chun-Kuang.
    > > >
    > > > > +
    > > > > +#endif /* __MTK_DEVAPC_H__ */
    > > > > --
    > > > > 1.7.9.5
    > > > > _______________________________________________
    > > > > Linux-mediatek mailing list
    > > > > Linux-mediatek@lists.infradead.org
    > > > > http://lists.infradead.org/mailman/listinfo/linux-mediatek
    > >

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