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 | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 90e784e7b721..cf1a4a3dd35d 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 +270,11 @@ static void vm_reset(struct virtio_device *vdev)
/* 0 status means a reset. */
writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
+ /* After writing 0 to device_status, the driver MUST wait for a read of
+ * device_status to return 0 before reinitializing the device.
+ */
+ while (readl(vm_dev->base + VIRTIO_MMIO_STATUS))
+ msleep(1);
}
--
2.17.1
