Re: [RESEND PATCH] driver core: Clear FWNODE_FLAG_LINKS_ADDED in device_links_purge()

Greg KH
2023-09-27T05:57:49Z

On Wed, Sep 27, 2023 at 10:30:10AM +0800, Zhenhua Huang wrote:
> Flag FWNODE_FLAG_LINKS_ADDED stops fwnode links creation. Current kernel
> only adds it once after fwnode links creation in fw_devlink_parse_fwnode().
> After that even device links being purged, the flag will not be cleared.
>
> Fwnode links are converted to device links and will not be added back
> forever in normal case. Essentially if a device is registered and
> unregisted (also deleted) before it is probed (due to missing fwlink
> dependencies, abort in device_links_check_suppliers), the fwlink is not
> setup next when device is newly created again. This means the probe gets
> called without meeting all dependencies.
>
> It usuallly happens in the case of a glue driver. Of_platform_populate()
> allows us to populate subnodes. We may do it in ancestor node probing
> function, then check subnode's probing status because there may be chances
> that suppliers of subnode are not ready. We may further need to do
> of_platform_depopulate(which purges device links) and in some time
> of_platform_populate() again. Such case we miss fwnode links(so that device
> links) during second time of populating subnodes.
>
> Fix it by Clearing FWNODE_FLAG_LINKS_ADDED flag in purging device link
> func, indicates both fwnode links and device links are absent.
>
> Signed-off-by: Zhenhua Huang <quic_zhenhuah@quicinc.com>
> ---
> drivers/base/core.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index b7d7f41..2a1975d 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -1630,6 +1630,10 @@ static void device_links_purge(struct device *dev)
> __device_link_del(&link->kref);
> }
>
> + /* Clear flags in fwnode. Give a chance to create fwnode link again */
> + if (dev->fwnode)
> + dev->fwnode->flags &= ~FWNODE_FLAG_LINKS_ADDED;
> +
> device_links_write_unlock();
> }
>
> --
> 2.7.4
>

Why is this a RESEND? What was wrong with the first version?