On Thu, Feb 11, 2021 at 1:02 AM Saravana Kannan <saravanak@xxxxxxxxxx> wrote: > > On Thu, Jan 28, 2021 at 7:03 AM Jon Hunter <jonathanh@xxxxxxxxxx> wrote: > > > > > > On 14/01/2021 16:56, Jon Hunter wrote: > > > > > > On 14/01/2021 16:47, Saravana Kannan wrote: > > > > > > ... > > > > > >>> Yes this is the warning shown here [0] and this is coming from > > >>> the 'Generic PHY stmmac-0:00' device. > > >> > > >> Can you print the supplier and consumer device when this warning is > > >> happening and let me know? That'd help too. I'm guessing the phy is > > >> the consumer. > > > > > > > > > Sorry I should have included that. I added a print to dump this on > > > another build but failed to include here. > > > > > > WARNING KERN Generic PHY stmmac-0:00: supplier 2200000.gpio (status 1) > > > > > > The status is the link->status and looks like the supplier is the > > > gpio controller. I have verified that the gpio controller is probed > > > before this successfully. > > > > > >> So the warning itself isn't a problem -- it's not breaking anything or > > >> leaking memory or anything like that. But the device link is jumping > > >> states in an incorrect manner. With enough context of this code (why > > >> the device_bind_driver() is being called directly instead of going > > >> through the normal probe path), it should be easy to fix (I'll just > > >> need to fix up the device link state). > > > > > > Correct, the board seems to boot fine, we just get this warning. > > > > > > Have you had chance to look at this further? > > Hi Jon, > > I finally got around to looking into this. Here's the email[1] that > describes why it's done this way. > > [1] - https://lore.kernel.org/lkml/YCRjmpKjK0pxKTCP@xxxxxxx/ > > > > > The following does appear to avoid the warning, but I am not sure if > > this is the correct thing to do ... > > > > index 9179825ff646..095aba84f7c2 100644 > > --- a/drivers/base/dd.c > > +++ b/drivers/base/dd.c > > @@ -456,6 +456,10 @@ int device_bind_driver(struct device *dev) > > { > > int ret; > > > > + ret = device_links_check_suppliers(dev); > > + if (ret) > > + return ret; > > + > > ret = driver_sysfs_add(dev); > > if (!ret) > > driver_bound(dev); > > So digging deeper into the usage of device_bind_driver and looking at > [1], it doesn't look like returning an error here is a good option. > When device_bind_driver() is called, the driver's probe function isn't > even called. So, there's no way for the driver to even defer probing > based on any of the suppliers. So, we have a couple of options: > > 1. Delete all the links to suppliers that haven't bound. Or maybe convert them to stateless links? Would that be doable at all? > We'll still leave the links to active suppliers alone in case it helps with > suspend/resume correctness. > 2. Fix the warning to not warn on suppliers that haven't probed if the > device's driver has no probe function. But this will also need fixing > up the cleanup part when device_release_driver() is called. Also, I'm > not sure if device_bind_driver() is ever called when the driver > actually has a probe() function. > > Rafael, > > Option 1 above is pretty straightforward. I would prefer this -> > Option 2 would look something like what's at the end of this email + > caveat about whether the probe check is sufficient. -> because "fix the warning" really means that we haven't got the device link state machine right and getting it right may imply a major redesign. Overall, I'd prefer to take a step back and allow things to stabilize for a while to let people catch up with this. > Do you have a preference between Option 1 vs 2? Or do you have some > other option in mind? > > Thanks, > Saravana > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index 5481b6940a02..8102b3c48bbc 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -1247,7 +1247,8 @@ void device_links_driver_bound(struct device *dev) > */ > device_link_drop_managed(link); > } else { > - WARN_ON(link->status != DL_STATE_CONSUMER_PROBE); > + WARN_ON(link->status != DL_STATE_CONSUMER_PROBE && > + dev->driver->probe); > WRITE_ONCE(link->status, DL_STATE_ACTIVE); > } > > @@ -1302,7 +1303,8 @@ static void __device_links_no_driver(struct device *dev) > if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) { > WRITE_ONCE(link->status, DL_STATE_AVAILABLE); > } else { > - WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY)); > + WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY) && > + dev->driver->probe); > WRITE_ONCE(link->status, DL_STATE_DORMANT); > } > }
