From:   "Michael Kelley (LINUX)" <mikelley@microsoft.com>
To:     Saurabh Sengar <ssengar@linux.microsoft.com>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "krzysztof.kozlowski+dt@linaro.org" 
        <krzysztof.kozlowski+dt@linaro.org>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        "wei.liu@kernel.org" <wei.liu@kernel.org>,
        Dexuan Cui <decui@microsoft.com>,
        "daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "lenb@kernel.org" <lenb@kernel.org>,
        "rafael@kernel.org" <rafael@kernel.org>,
        "linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>
Subject: RE: [PATCH v7 5/5] Driver: VMBus: Add Devicetree support
Thread-Topic: [PATCH v7 5/5] Driver: VMBus: Add Devicetree support
Thread-Index: AQHZR3oO8XCRAJVOTEyd9eleCYLxd674F9KA
Date:   Mon, 13 Mar 2023 02:33:53 +0000
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References: <1677151745-16521-1-git-send-email-ssengar@linux.microsoft.com>
 <1677151745-16521-6-git-send-email-ssengar@linux.microsoft.com>
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From: Saurabh Sengar <ssengar@linux.microsoft.com> Sent: Thursday, February=
 23, 2023 3:29 AM
>=20
> Update the driver to support Devicetree boot as well along with ACPI.
> At present the Devicetree parsing only provides the mmio region info
> and is not the exact copy of ACPI parsing. This is sufficient to cater
> all the current Devicetree usecases for VMBus.
>=20
> Currently Devicetree is supported only for x86 systems.
>=20
> Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
> ---
> [V7]
> - Use cpu_addr instead of bus_addr
>=20
>  drivers/hv/Kconfig     |  6 +++--
>  drivers/hv/vmbus_drv.c | 57 ++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 59 insertions(+), 4 deletions(-)
>=20
> diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
> index 0747a8f1fcee..1a55bf32d195 100644
> --- a/drivers/hv/Kconfig
> +++ b/drivers/hv/Kconfig
> @@ -4,11 +4,13 @@ menu "Microsoft Hyper-V guest support"
>=20
>  config HYPERV
>  	tristate "Microsoft Hyper-V client drivers"
> -	depends on ACPI && ((X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \
> -		|| (ARM64 && !CPU_BIG_ENDIAN))
> +	depends on (X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \
> +		|| (ACPI && ARM64 && !CPU_BIG_ENDIAN)
>  	select PARAVIRT
>  	select X86_HV_CALLBACK_VECTOR if X86
>  	select VMAP_PFN
> +	select OF if !ACPI
> +	select OF_EARLY_FLATTREE if !ACPI
>  	help
>  	  Select this option to run Linux as a Hyper-V client operating
>  	  system.

One further thing occurred to me.  OF_EARLY_FLATTREE really depends
on OF instead of ACPI.   The ACPI dependency is indirect through OF.  So
I'd suggest doing

	select OF_EARLY_FLATTRE if OF

to express the direct dependency.

Separately, I wonder if the "select OF if !ACPI" is even needed.  It doesn'=
t
hurt anything to leave it, but it seems like any config that doesn't
independently select either ACPI or OF is broken for reasons unrelated
to Hyper-V.   I'm OK with leaving the select of OF if you want, so I'm
more just wondering than asserting it should be removed.   I didn't
see "select OF if !ACPI" anywhere else in the Kconfig files, and it
seems like Hyper-V would not be the only environment where this
is the expectation.

Michael