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FROMLIST: remoteproc: core: Move cdev add before device add

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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>

Bug: 185924092
Change-Id: Iad8a45f564996d73cd3f33ed124427cb73497dad
Link: https://lore.kernel.org/linux-remoteproc/1618946805-26970-1-git-send-email-sidgup@codeaurora.org/
Signed-off-by: Siddharth Gupta <quic_sidgup@quicinc.com>
This commit is contained in:
Siddharth Gupta 2021-04-20 16:02:10 -07:00 • committed by Todd Kjos
commit 4ccc2a6dbc
1 changed files with 5 additions and 5 deletions
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10
drivers/remoteproc/remoteproc_core.c
View file

@ -1996,6 +1996,11 @@ 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;
@ -2009,11 +2014,6 @@ 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;
/*
* Remind ourselves the remote processor has been attached to rather
* than booted by the remoteproc core. This is important because the