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virtio: Add polling virtio-mmio device reset completion

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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_jianguos@quicinc.com>
Signed-off-by: Sreenad Menon <quic_sreemeno@quicinc.com>
This commit is contained in:
Jianguo Sun 2024-04-03 19:59:13 +08:00
parent f8d51a3599
commit 4cb39792d0
1 changed files with 8 additions and 0 deletions
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8
drivers/virtio/virtio_mmio.c
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@ -70,6 +70,7 @@
#include <linux/virtio_config.h> #include <linux/virtio_config.h>
#include <uapi/linux/virtio_mmio.h> #include <uapi/linux/virtio_mmio.h>
#include <linux/virtio_ring.h> #include <linux/virtio_ring.h>
#include <linux/delay.h>
#ifdef CONFIG_GH_VIRTIO_DEBUG #ifdef CONFIG_GH_VIRTIO_DEBUG
#define CREATE_TRACE_POINTS #define CREATE_TRACE_POINTS
@ -292,6 +293,13 @@ static void vm_reset(struct virtio_device *vdev)
/* 0 status means a reset. */ /* 0 status means a reset. */
writel(0, vm_dev->base + VIRTIO_MMIO_STATUS); 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.
*/
while (readl(vm_dev->base + VIRTIO_MMIO_STATUS))
usleep_range(1000, 1100);
#endif
} }