Re: [PATCH 2/3] remoteproc: k3-r5: Acquire mailbox handle during probe

From: Beleswar Prasad Padhi
Date: Tue Jun 04 2024 - 01:24:19 EST


Hi Andrew,

On 30/05/24 19:46, Andrew Davis wrote:
On 5/30/24 4:07 AM, Beleswar Padhi wrote:
Acquire the mailbox handle during device probe and do not release handle
in stop/detach routine or error paths. This removes the redundant
requests for mbox handle later during rproc start/attach. This also
allows to defer remoteproc driver's probe if mailbox is not probed yet.

Signed-off-by: Beleswar Padhi <b-padhi@xxxxxx>
---
  drivers/remoteproc/ti_k3_r5_remoteproc.c | 66 ++++++++----------------
  1 file changed, 21 insertions(+), 45 deletions(-)

diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
index 26362a509ae3..157e8fd57665 100644
--- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
+++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
@@ -391,6 +391,7 @@ static int k3_r5_rproc_request_mbox(struct rproc *rproc)
      struct mbox_client *client = &kproc->client;
      struct device *dev = kproc->dev;
      int ret;
+    long err;
        client->dev = dev;
      client->tx_done = NULL;
@@ -400,10 +401,9 @@ static int k3_r5_rproc_request_mbox(struct rproc *rproc)
        kproc->mbox = mbox_request_channel(client, 0);
      if (IS_ERR(kproc->mbox)) {
-        ret = -EBUSY;
-        dev_err(dev, "mbox_request_channel failed: %ld\n",
-            PTR_ERR(kproc->mbox));
-        return ret;
+        err = PTR_ERR(kproc->mbox);
+        dev_err(dev, "mbox_request_channel failed: %ld\n", err);
+        return (err == -EPROBE_DEFER) ? -EPROBE_DEFER : -EBUSY;

Why turn all other errors into EBUSY? If you just return the error as-is you
can simply make these 3 lines just:

return dev_err_probe(dev, PTR_ERR(kproc->mbox), "mbox_request_channel failed\n");

      }
        /*
@@ -552,10 +552,6 @@ static int k3_r5_rproc_start(struct rproc *rproc)
      u32 boot_addr;
      int ret;
  -    ret = k3_r5_rproc_request_mbox(rproc);
-    if (ret)
-        return ret;
-
      boot_addr = rproc->bootaddr;
      /* TODO: add boot_addr sanity checking */
      dev_dbg(dev, "booting R5F core using boot addr = 0x%x\n", boot_addr);
@@ -564,7 +560,7 @@ static int k3_r5_rproc_start(struct rproc *rproc)
      core = kproc->core;
      ret = ti_sci_proc_set_config(core->tsp, boot_addr, 0, 0);
      if (ret)
-        goto put_mbox;
+        goto out;

The label "out" doesn't do anything, just directly `return ret;` here and
in the other cases below.

        /* unhalt/run all applicable cores */
      if (cluster->mode == CLUSTER_MODE_LOCKSTEP) {
@@ -581,12 +577,12 @@ static int k3_r5_rproc_start(struct rproc *rproc)
              dev_err(dev, "%s: can not start core 1 before core 0\n",
                  __func__);
              ret = -EPERM;
-            goto put_mbox;
+            goto out;
          }
            ret = k3_r5_core_run(core);
          if (ret)
-            goto put_mbox;
+            goto out;
      }
        return 0;
@@ -596,8 +592,7 @@ static int k3_r5_rproc_start(struct rproc *rproc)
          if (k3_r5_core_halt(core))
              dev_warn(core->dev, "core halt back failed\n");
      }
-put_mbox:
-    mbox_free_channel(kproc->mbox);
+out:
      return ret;
  }
  @@ -658,8 +653,6 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
              goto out;
      }
  -    mbox_free_channel(kproc->mbox);
-
      return 0;
    unroll_core_halt:
@@ -674,42 +667,21 @@ static int k3_r5_rproc_stop(struct rproc *rproc)
  /*
   * Attach to a running R5F remote processor (IPC-only mode)
   *
- * The R5F attach callback only needs to request the mailbox, the remote
- * processor is already booted, so there is no need to issue any TI-SCI
- * commands to boot the R5F cores in IPC-only mode. This callback is invoked
- * only in IPC-only mode.
+ * The R5F attach callback is a NOP. The remote processor is already booted, and
+ * all required resources have been acquired during probe routine, so there is
+ * no need to issue any TI-SCI commands to boot the R5F cores in IPC-only mode.
+ * This callback is invoked only in IPC-only mode and exists for sanity sake.
   */
-static int k3_r5_rproc_attach(struct rproc *rproc)
-{
-    struct k3_r5_rproc *kproc = rproc->priv;
-    struct device *dev = kproc->dev;
-    int ret;
-
-    ret = k3_r5_rproc_request_mbox(rproc);
-    if (ret)
-        return ret;
-
-    dev_info(dev, "R5F core initialized in IPC-only mode\n");
-    return 0;
-}
+static int k3_r5_rproc_attach(struct rproc *rproc) { return 0; }
    /*
   * Detach from a running R5F remote processor (IPC-only mode)
   *
- * The R5F detach callback performs the opposite operation to attach callback
- * and only needs to release the mailbox, the R5F cores are not stopped and
- * will be left in booted state in IPC-only mode. This callback is invoked
- * only in IPC-only mode.
+ * The R5F detach callback is a NOP. The R5F cores are not stopped and will be
+ * left in booted state in IPC-only mode. This callback is invoked only in
+ * IPC-only mode and exists for sanity sake.
   */
-static int k3_r5_rproc_detach(struct rproc *rproc)
-{
-    struct k3_r5_rproc *kproc = rproc->priv;
-    struct device *dev = kproc->dev;
-
-    mbox_free_channel(kproc->mbox);
-    dev_info(dev, "R5F core deinitialized in IPC-only mode\n");
-    return 0;
-}
+static int k3_r5_rproc_detach(struct rproc *rproc) { return 0; }

Do we still need to disable the mbox channel somehow here to prevent
receiving more messages from the detached core?

    /*
   * This function implements the .get_loaded_rsc_table() callback and is used
@@ -1277,6 +1249,10 @@ static int k3_r5_cluster_rproc_init(struct platform_device *pdev)
          kproc->rproc = rproc;
          core->rproc = rproc;
  +        ret = k3_r5_rproc_request_mbox(rproc);

Now that we get the channel here in init you'll want to add a matching
mbox_free_channel() call to k3_r5_cluster_rproc_exit().

Andrew


Thanks for the review! I have sent out v2 addressing these comments:

https://lore.kernel.org/all/20240604051722.3608750-1-b-padhi@xxxxxx/


+        if (ret)
+            return ret;
+
          ret = k3_r5_rproc_configure_mode(kproc);
          if (ret < 0)
              goto err_config;