On Thu, 31 Mar 2022 11:25:43 +0200, Heikki Krogerus wrote:
On Thu, Mar 31, 2022 at 11:12:55AM +0200, Takashi Iwai wrote:
if (!strcmp(dev->driver->name, "i915") &&
if (dev->driver && !strcmp(dev->driver->name, "i915") &&Can NULL dev->driver be really seen? I thought the components are added by the drivers, hence they ought to have the driver field set. But there can be corner cases I overlooked.
thanks,
Takashi
Hi Takashi,
When I try using component_add in a different driver (usb4 in my case), I think dev->driver here is NULL because the i915 drivers do not have their component master fully bound when this new component is registered. When I test it, it seems to be causing a crash.
Hm, from where component_add*() is called? Basically dev->driver must be already set before the corresponding driver gets bound at __driver_probe_deviec(). So, if the device is added to component from the corresponding driver's probe, dev->driver must be non-NULL.
The code that declares a device as component does not have to be the driver of that device.
In our case the components are USB ports, and they are devices that are actually never bind to any drivers: drivers/usb/core/port.c
OK, that's what I wanted to know. It'd be helpful if it's more clearly mentioned in the commit log.
BTW, the same problem must be seen in MEI drivers, too.
Takashi