Re: [PATCH 1/4] amba: Export amba_bustype

[Robin Murphy <robin.murphy@arm.com>]

On 16/05/18 10:18, Russell King - ARM Linux wrote:
> On Wed, May 16, 2018 at 12:16:28PM +0300, Andy Shevchenko wrote:
>> On Tue, May 8, 2018 at 10:06 PM, Kim Phillips <kim.phillips@arm.com> wrote:
>>> This patch is provided in the context of allowing the Coresight driver
>>> subsystem to be loaded as modules.  Coresight uses amba_bus in its call
>>> to bus_find_device() in of_coresight_get_endpoint_device() when
>>> searching for a configurable endpoint device.  This patch allows
>>> Coresight to reference amba_bustype when built as a module.
>>
>>> --- a/drivers/amba/bus.c
>>> +++ b/drivers/amba/bus.c
>>> @@ -197,6 +197,7 @@ struct bus_type amba_bustype = {
>>>          .pm             = &amba_pm,
>>>          .force_dma      = true,
>>>   };
>>> +EXPORT_SYMBOL_GPL(amba_bustype);
>>
>> Oh,
>>
>> What wrong with the approach let's say similar to PCI bus?
>>
>> Whenever you have a struct device you may use two helpers:
>>
>> dev_is_pci() -> is the device of PCI bus type?
>> to_pci_dev() -> get's container of struct device for PCI bus case
> 
> How does that help with bus_find_device() which requires the bus_type
> structure for the type of devices to be searched?
Not to mention that dev_is_pci() still relies on pci_bus_type itself 
being exported anyway.

Robin.