linux-kernel - 回复: [PATCH] firmware: arm_scmi: Set device ready before register scmi_virtio

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Message-ID: <00e501dc0b60$0f965a70$2ec30f50$@163.com>
Date: Tue, 12 Aug 2025 16:06:51 +0800
From: <yizhijiao2025@....com>
To: "'Junnan Wu'" <junnan01.wu@...sung.com>,
	<sudeep.holla@....com>,
	<cristian.marussi@....com>
Cc: <florian.fainelli@...adcom.com>,
	<arm-scmi@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>,
	<lei19.wang@...sung.com>,
	<q1.huang@...sung.com>
Subject: 回复: [PATCH] firmware: arm_scmi: Set device ready before register scmi_virtio_driver



-----邮件原件-----
发件人: arm-scmi+bounces-2017-yizhijiao2025=163.com@...r.kernel.org <arm-scmi+bounces-2017-yizhijiao2025=163.com@...r.kernel.org> 代表 Junnan Wu
发送时间: 2025年8月12日 15:54
收件人: sudeep.holla@....com; cristian.marussi@....com
抄送: florian.fainelli@...adcom.com; arm-scmi@...r.kernel.org; linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; lei19.wang@...sung.com; q1.huang@...sung.com; Junnan Wu <junnan01.wu@...sung.com>
主题: [PATCH] firmware: arm_scmi: Set device ready before register scmi_virtio_driver

Fix irregularities in scmi driver probe.

After 'commit 20bda12a0ea0 ("firmware: arm_scmi: Make VirtIO transport a standalone driver")'
making SCMI VirtIO transport a standalone driver, `scmi_virtio_probe` will follow `scmi_vio_probe`, and during `scmi_virtio_probe`, it will do `scmi_probe` which will invoke function `scmi_protocol_acquire(handle, SCMI_PROTOCOL_BASE)`, and this function will send message via virtqueue and wait device's reply

Before this patch, only after `scmi_vio_probe`, frontend will mark device DRIVER_OK by function `virtio_dev_probe` in 'drivers/virtio/virtio.c' itself.

Accroding to chapter '3.1 Device Initialization' in virtio-spec, ``` The driver MUST NOT send any buffer available notifications to the device before setting DRIVER_OK.
```

In some type1-hypervisor, available buffer notifications will be intercepted until virtio driver is okay. In this case, `scmi_vio_probe` will be blocked at `scmi_wait_for_reply` and probe can never complete.

Therefore, the operation to set DRIVER_OK must follow perform device-specific setup immediately, then available buffer notifications can be sent in function `scmi_probe`.

Fixes: 20bda12a0ea0 ("firmware: arm_scmi: Make VirtIO transport a standalone driver")
Signed-off-by: Junnan Wu <junnan01.wu@...sung.com>
---
 drivers/firmware/arm_scmi/transports/virtio.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/arm_scmi/transports/virtio.c b/drivers/firmware/arm_scmi/transports/virtio.c
index cb934db9b2b4..326c4a93e44b 100644
--- a/drivers/firmware/arm_scmi/transports/virtio.c
+++ b/drivers/firmware/arm_scmi/transports/virtio.c
@@ -871,6 +871,9 @@ static int scmi_vio_probe(struct virtio_device *vdev)
 	/* Ensure initialized scmi_vdev is visible */
 	smp_store_mb(scmi_vdev, vdev);
 
+	/* Set device ready */
+	virtio_device_ready(vdev);
+
 	ret = platform_driver_register(&scmi_virtio_driver);
 	if (ret) {
 		vdev->priv = NULL;
--
2.34.1