linux-kernel - Re: [PATCH v13 1/6] soc: mediatek: mutex: add common interface to accommodate multiple modules operationg MUTEX

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Message-ID: <cdcf08d4-8b77-a94c-7906-073155b9865f@collabora.com>
Date:   Tue, 15 Mar 2022 15:58:21 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Rob Landley <rob@...dley.net>
Cc:     Moudy Ho <moudy.ho@...iatek.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-mediatek@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Alexandre Courbot <acourbot@...omium.org>,
        Tomasz Figa <tfiga@...omium.org>, drinkcat@...omium.org,
        Pi-Hsun Shih <pihsun@...omium.org>,
        Hsin-Yi Wang <hsinyi@...gle.com>,
        Maoguang Meng <maoguang.meng@...iatek.com>,
        daoyuan huang <daoyuan.huang@...iatek.com>,
        Ping-Hsun Wu <ping-hsun.wu@...iatek.com>,
        menghui.lin@...iatek.com, sj.huang@...iatek.com,
        allen-kh.cheng@...iatek.com, randy.wu@...iatek.com,
        jason-jh.lin@...iatek.com, roy-cw.yeh@...iatek.com,
        river.cheng@...iatek.com, srv_heupstream@...iatek.com,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v13 1/6] soc: mediatek: mutex: add common interface to
 accommodate multiple modules operationg MUTEX

Il 15/03/22 15:50, Geert Uytterhoeven ha scritto:
> Hi Rob,
> 
> On Tue, Mar 15, 2022 at 3:37 PM Rob Landley <rob@...dley.net> wrote:
>> On 3/15/22 4:10 AM, AngeloGioacchino Del Regno wrote:
>>> Il 15/03/22 07:10, Moudy Ho ha scritto:
>>>> In order to allow multiple modules to operate MUTEX hardware through
>>>> a common interfrace, a flexible index "mtk_mutex_table_index" needs to
>>>> be added to replace original component ID so that like DDP and MDP
>>>> can add their own MUTEX table settings independently.
>>>>
>>>> In addition, 4 generic interface "mtk_mutex_set_mod", "mtk_mutex_set_sof",
>>>> "mtk_mutex_clear_mod" and "mtk_mutex_clear_sof" have been added, which is
>>>> expected to replace the "mtk_mutex_add_comp" and "mtk_mutex_remove_comp"
>>>> pair originally dedicated to DDP in the future.
>>>>
>>>> Signed-off-by: Moudy Ho <moudy.ho@...iatek.com>
> 
>>>> --- a/drivers/soc/mediatek/mtk-mutex.c
>>>> +++ b/drivers/soc/mediatek/mtk-mutex.c
>>>> @@ -156,6 +156,7 @@ struct mtk_mutex_data {
>>>>       const unsigned int *mutex_sof;
>>>>       const unsigned int mutex_mod_reg;
>>>>       const unsigned int mutex_sof_reg;
>>>> +    const unsigned long long *mutex_table_mod;
>>>
>>> Can we change this to u64 instead?
>>
>> Linux is still LP64, correct?
> 
> On 64-bit platforms, yes.
> 
> Note that this is about "long long", which is 64-bit on all Linux platforms.
> But as the table seems to be used to store 2 32-bit values, it doesn't hurt
> to be explicit and use "u64"? Or a struct with 2 "u32" values?
> 

Exactly. I wanted this to be a hint of what's happening in the background,
without using unions to describe this.

Geert, thanks for immediately understanding my intention.

Cheers,
Angelo

> Gr{oetje,eeting}s,
> 
>                          Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                  -- Linus Torvalds