linux-kernel - RE: [PATCH -next 1/2] i2c: designware: Switch from using MMIO access to SMN access

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Message-ID: <MN0PR12MB61011C8ED719A2FBDF823E17E2FE9@MN0PR12MB6101.namprd12.prod.outlook.com>
Date:   Mon, 9 Jan 2023 17:10:45 +0000
From:   "Limonciello, Mario" <Mario.Limonciello@....com>
To:     Grzegorz Bernacki <gjb@...ihalf.com>,
        Borislav Petkov <bp@...en8.de>,
        Jan Dąbroś <jsd@...ihalf.com>
CC:     Borislav Petkov <bp@...e.de>, Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "jarkko.nikula@...ux.intel.com" <jarkko.nikula@...ux.intel.com>,
        "wsa@...nel.org" <wsa@...nel.org>,
        "rrangel@...omium.org" <rrangel@...omium.org>,
        "upstream@...ihalf.com" <upstream@...ihalf.com>,
        "M K, Muralidhara" <Muralidhara.MK@....com>,
        "Chatradhi, Naveen Krishna" <NaveenKrishna.Chatradhi@....com>,
        "Ghannam, Yazen" <Yazen.Ghannam@....com>,
        "Mukunda, Vijendar" <Vijendar.Mukunda@....com>
Subject: RE: [PATCH -next 1/2] i2c: designware: Switch from using MMIO access
 to SMN access

[Public]

+Grzegorz who Jan mentioned is taking over some of this.
+Vijendar for sound/soc/amd

> -----Original Message-----
> From: Borislav Petkov <bp@...en8.de>
> Sent: Monday, January 9, 2023 05:12
> To: Jan Dąbroś <jsd@...ihalf.com>; Limonciello, Mario
> <Mario.Limonciello@....com>
> Cc: Borislav Petkov <bp@...e.de>; Hans de Goede
> <hdegoede@...hat.com>; Andy Shevchenko
> <andriy.shevchenko@...ux.intel.com>; linux-kernel@...r.kernel.org; linux-
> i2c@...r.kernel.org; jarkko.nikula@...ux.intel.com; wsa@...nel.org;
> rrangel@...omium.org; upstream@...ihalf.com; M K, Muralidhara
> <Muralidhara.MK@....com>; Chatradhi, Naveen Krishna
> <NaveenKrishna.Chatradhi@....com>; Ghannam, Yazen
> <Yazen.Ghannam@....com>
> Subject: Re: [PATCH -next 1/2] i2c: designware: Switch from using MMIO
> access to SMN access
> 
> Another forgotten thread... ;-\
> 
> + Yazen.
> 
> On Fri, Oct 28, 2022 at 10:32:20AM +0200, Jan Dąbroś wrote:
> > So to summarize everything, I would like below order:
> >
> > acpi_init() -> init_amd_nbs() -> dw_i2c_init_driver()
> > ^--subsys_initcall   ^--fs_initicall            ^--subsys_initcall
> >
> > but I don't have a clear idea how to achieve this in a clean way.
> >
> > The only option seems to be to register init_amd_nbs() as
> > subsys_initcall and force it to execute after acpi_init() and before
> > dw_i2c_init_drvier(). However the only option (if I'm not mistaken)
> > for forcing order on initcalls placed on the same level is to modify
> > their order within Makefile, so that linker puts them in the "init"
> > section with addresses in desired order. This doesn't seem to be an
> > option for upstream.
> >
> > Do you have any clue how to solve this problem?
> 
> Make init_amd_nbs() arch_initcall_sync() so that it executes after PCI init.
> 
> By the time subsys_initcalls come, they'll have all the facilities they need,
> prepared for them...
> 
> Along with big fat comment why.
> 
> Btw, note to myself as I keep wondering about it each time: the sync calls
> come
> after the regular ones, in link order if you look at preprocessed linker script
> arch/x86/kernel/vmlinux.lds:
> 
> __initcall_start = .;
>  KEEP(*(.initcallearly.init)) __initcall0_start = .;
>  KEEP(*(.initcall0.init)) KEEP(*(.initcall0s.init)) __initcall1_start = .;
>  KEEP(*(.initcall1.init)) KEEP(*(.initcall1s.init)) __initcall2_start = .;
>  KEEP(*(.initcall2.init)) KEEP(*(.initcall2s.init)) __initcall3_start = .;
>  KEEP(*(.initcall3.init)) KEEP(*(.initcall3s.init)) __initcall4_start = .;
>  KEEP(*(.initcall4.init)) KEEP(*(.initcall4s.init)) __initcall5_start = .;
>  KEEP(*(.initcall5.init)) KEEP(*(.initcall5s.init)) __initcallrootfs_start = .;
>  KEEP(*(.initcallrootfs.init)) KEEP(*(.initcallrootfss.init)) __initcall6_start = .;
>  KEEP(*(.initcall6.init)) KEEP(*(.initcall6s.init)) __initcall7_start = .;
>  KEEP(*(.initcall7.init)) KEEP(*(.initcall7s.init)) __initcall_end = .;
> 
> Mario, is that something that would work for what you wanna do too?
> 

Yeah I guess as long as the I2C init comes after arch_initcall_sync this should work.

If it works for Jan & Grzegorz, then I think we can also adjust the "effectively local
copy" of amd_smn_write/amd_smn_read that got added into sound/soc/amd
to use this too now and it should work for what I wanted to do too.

Jan/Grzegorz can you please have a try on your system and comment?

> Thx.
> 
> --
> Regards/Gruss,
>     Boris.
> 
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