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Message-ID: <e410d65754ba6a11ad7f74b27dc28d9a25d8c82e.camel@infradead.org>
Subject: Re: [RFC PATCH v3 6/7] virtio_rtc: Add Arm Generic Timer
 cross-timestamping
From: David Woodhouse <dwmw2@infradead.org>
To: Peter Hilber <peter.hilber@opensynergy.com>,
 linux-kernel@vger.kernel.org,  virtualization@lists.linux.dev,
 virtio-dev@lists.oasis-open.org,  linux-arm-kernel@lists.infradead.org
Cc: "Michael S. Tsirkin" <mst@redhat.com>, Jason Wang <jasowang@redhat.com>,
  Xuan Zhuo <xuanzhuo@linux.alibaba.com>, Marc Zyngier <maz@kernel.org>,
 Mark Rutland <mark.rutland@arm.com>, Daniel Lezcano
 <daniel.lezcano@linaro.org>, Thomas Gleixner <tglx@linutronix.de>
Date: Sat, 15 Jun 2024 08:50:53 +0100
In-Reply-To: <20231218073849.35294-7-peter.hilber@opensynergy.com>
References: <20231218073849.35294-1-peter.hilber@opensynergy.com>
	 <20231218073849.35294-7-peter.hilber@opensynergy.com>
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On Mon, 2023-12-18 at 08:38 +0100, Peter Hilber wrote:
>=20
> +int viortc_hw_xtstamp_params(u16 *hw_counter, enum clocksource_ids *cs_i=
d)
> +{
> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0*hw_counter =3D VIRTIO_RTC_COU=
NTER_ARM_VIRT;

Hm, but what if it isn't? I think you need to put this in
drivers/clocksource/arm_arch_timer.c where it can do something like
kvm_arch_ptp_get_crosststamp() does to decide:

        if (arch_timer_uses_ppi =3D=3D ARCH_TIMER_VIRT_PPI)
                ptp_counter =3D KVM_PTP_VIRT_COUNTER;
        else
                ptp_counter =3D KVM_PTP_PHYS_COUNTER;


> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0*cs_id =3D CSID_ARM_ARCH_COUNT=
ER;
> +
> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0return 0;
> +}


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