From: Siddharth Gupta <sidgup@codeaurora.org>
To: bjorn.andersson@linaro.org, ohad@wizery.com,
linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Siddharth Gupta <sidgup@codeaurora.org>,
psodagud@codeaurora.org, eberman@codeaurora.org
Subject: [PATCH] remoteproc: core: Move cdev add before device add
Date: Tue, 20 Apr 2021 12:26:45 -0700 [thread overview]
Message-ID: <1618946805-26970-1-git-send-email-sidgup@codeaurora.org> (raw)
When cdev_add is called after device_add has been called there is no
way for the userspace to know about the addition of a cdev as cdev_add
itself doesn't trigger a uevent notification, or for the kernel to
know about the change to devt. This results in two problems:
- mknod is never called for the cdev and hence no cdev appears on
devtmpfs.
- sysfs links to the new cdev are not established.
Based on how cdev_device_add[1] is written, it appears that the correct
way to use these APIs is to call cdev_add before device_add is called.
Since the cdev is an optional feature for remoteproc we cannot directly
use the existing API. Hence moving rproc_char_device_add() before
device_add() in rproc_add().
[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/char_dev.c#n537
Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
---
drivers/remoteproc/remoteproc_core.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 626a6b90f..562355a 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -2316,6 +2316,11 @@ int rproc_add(struct rproc *rproc)
struct device *dev = &rproc->dev;
int ret;
+ /* add char device for this remoteproc */
+ ret = rproc_char_device_add(rproc);
+ if (ret < 0)
+ return ret;
+
ret = device_add(dev);
if (ret < 0)
return ret;
@@ -2329,11 +2334,6 @@ int rproc_add(struct rproc *rproc)
/* create debugfs entries */
rproc_create_debug_dir(rproc);
- /* add char device for this remoteproc */
- ret = rproc_char_device_add(rproc);
- if (ret < 0)
- return ret;
-
/* if rproc is marked always-on, request it to boot */
if (rproc->auto_boot) {
ret = rproc_trigger_auto_boot(rproc);
--
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
next reply other threads:[~2021-04-20 19:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-20 19:26 Siddharth Gupta [this message]
2021-04-22 18:04 ` [PATCH] remoteproc: core: Move cdev add before device add Mathieu Poirier
2021-04-23 2:12 ` Siddharth Gupta
2021-04-23 3:01 ` Bjorn Andersson
2021-04-23 21:48 ` Siddharth Gupta
2021-06-23 21:50 ` patchwork-bot+linux-remoteproc
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