On Sun, Sep 22, 2024 at 08:34:35PM +0800, Jianguo Sun wrote: > We write 0 to device_status to initiate reset of a virtio-mmio device. > The reset operation itself may or may not be completed by the time > write instruction completes. Add polling device_status to return > 0 to ensure reset completion before reinitializing the device. > > Change-Id: If15d11d090dfd0d4972ad35f49af03e076872413 > Signed-off-by: Jianguo Sun <quic_jiang...@quicinc.com> > Signed-off-by: Sreenad Menon <quic_sreem...@quicinc.com> > Signed-off-by: Anant Goel <quic_ana...@quicinc.com> > --- > drivers/virtio/virtio_mmio.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c > index 90e784e7b721..c34ad1782145 100644 > --- a/drivers/virtio/virtio_mmio.c > +++ b/drivers/virtio/virtio_mmio.c > @@ -70,6 +70,7 @@ > #include <linux/virtio_config.h> > #include <uapi/linux/virtio_mmio.h> > #include <linux/virtio_ring.h> > +#include <linux/delay.h> > > > > @@ -269,6 +270,13 @@ static void vm_reset(struct virtio_device *vdev) > > /* 0 status means a reset. */ > writel(0, vm_dev->base + VIRTIO_MMIO_STATUS); > +#ifdef CONFIG_VIRTIO_MMIO_POLL_RESET > + /* After writing 0 to device_status, the driver MUST wait for a read of > + * device_status to return 0 before reinitializing the device. > + */
This is not in the spec, is it? First you need a spec patch. Then implement it. > + while (readl(vm_dev->base + VIRTIO_MMIO_STATUS)) > + usleep_range(1000, 1100); > +#endif > } > > > -- > 2.17.1
