VirtQueue: Poll for VDEV status in VirtQueue_startup() to sync rpmsg on boot.

Previously, various methods (or none) have been implemented to ensure that
the slave has buffers available in the vring to the host before sending its
first message.

VirtQueue_startup() now polls the status bit in the VDEV struct of the Resource
table for a completion status, written by the host after the VDEV is created
successfully.

This resolves a race condition where the first slave RPMSG send would block
in a non-task context on a Semaphore_pend(), when the slave loads faster than
than the host can prime the send buffers in the vring to the host.

This patch implements the solution for Vayu separately.

Signed-off-by: G Anthony <a0783926@ti.com>

diff --git a/packages/ti/ipc/family/vayu/VirtQueue.c b/packages/ti/ipc/family/vayu/VirtQueue.c
index 80310820508d6b8ba5a0425b6f17a22782686f74..42e9b8680afe849481b3c27760f2cb7c80545698 100644 (file)
--- a/packages/ti/ipc/family/vayu/VirtQueue.c
+++ b/packages/ti/ipc/family/vayu/VirtQueue.c
@@ -80,6 +80,8 @@
 #endif
 #include <string.h>
 
 #endif
 #include <string.h>
 

+#include <ti/ipc/remoteproc/Resource.h>
+#include <ti/ipc/remoteproc/rsc_types.h>

 #include <ti/ipc/rpmsg/_VirtQueue.h>
 
 #include <ti/sdo/ipc/notifyDrivers/IInterrupt.h>
 #include <ti/ipc/rpmsg/_VirtQueue.h>
 
 #include <ti/sdo/ipc/notifyDrivers/IInterrupt.h>


@@ -605,6 +607,17 @@ VirtQueue_Handle VirtQueue_create(UInt16 remoteProcId, VirtQueue_Params *params,
     return (vq);
 }
 
     return (vq);
 }
 

+/*
+ *  The following three VIRTIO_* defines must match those in
+ *  <Linux_kernel>/include/uapi/linux/virtio_config.h
+ */
+#define VIRTIO_CONFIG_S_ACKNOWLEDGE     1
+#define VIRTIO_CONFIG_S_DRIVER          2
+#define VIRTIO_CONFIG_S_DRIVER_OK       4
+
+#define VRING_BUFS_PRIMED  (VIRTIO_CONFIG_S_ACKNOWLEDGE | \
+                            VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK)
+

 /*!
  * ======== VirtQueue_startup ========
  */
 /*!
  * ======== VirtQueue_startup ========
  */


@@ -624,7 +637,22 @@ Void VirtQueue_startup()
     IpcPower_init();
 #endif
 
     IpcPower_init();
 #endif
 

+    /*
+     * Wait for HLOS (Virtio device) to indicate that priming of host's receive
+     * buffers is complete, indicating that host is ready to send.
+     *
+     * Though this is a Linux Virtio configuration status, it must be
+     * implemented by each non-Linux HLOS as well.
+     */
+    Log_print1(Diags_USER1, "VirtQueue_startup: VDEV status: 0x%x\n",
+              Resource_getVdevStatus(VIRTIO_ID_RPMSG));
+    Log_print0(Diags_USER1, "VirtQueue_startup: Polling VDEV status...\n");
+    while (Resource_getVdevStatus(VIRTIO_ID_RPMSG) != VRING_BUFS_PRIMED);
+    Log_print1(Diags_USER1, "VirtQueue_startup: VDEV status: 0x%x\n",
+              Resource_getVdevStatus(VIRTIO_ID_RPMSG));
+

     InterruptProxy_intRegister(hostProcId, &intInfo, (Fxn)VirtQueue_isr, NULL);
     InterruptProxy_intRegister(hostProcId, &intInfo, (Fxn)VirtQueue_isr, NULL);

+    Log_print0(Diags_USER1, "Passed VirtQueue_startup\n");

 }
 
 /*!
 }
 
 /*!