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SubjectRe: [PATCH 4/6] fpga: region: change fpga_region_register to have one param
On Thu, Mar 29, 2018 at 4:39 PM, Moritz Fischer <mdf@kernel.org> wrote:
> On Thu, Mar 29, 2018 at 03:42:51PM -0500, Alan Tull wrote:
>> On Thu, Mar 29, 2018 at 12:06 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
>>
>> Hi Greg,
>>
>> >> -int fpga_region_register(struct device *dev, struct fpga_region *region)
>> >> +int fpga_region_register(struct fpga_region *region)
>> >> {
>> >> + struct device *dev = region->parent;
>> >> int id, ret = 0;
>> >>
>> >> + if (!dev) {
>> >> + pr_err("Attempt to register fpga region without parent\n");
>> >> + return -EINVAL;
>> >> + }
>> >
>> > Are you sure you don't want a virtual device? That is what will happen
>> > if you do not have a parent, right? Or do you always want to have
>> > "real" devices?
>>
>> I don't want to restrict this to "real" devices, so yes, I'll be
>> removing this check.
>>
>> >> diff --git a/include/linux/fpga/fpga-region.h b/include/linux/fpga/fpga-region.h
>> >> index b6520318ab9c..423c87e3e29a 100644
>> >> --- a/include/linux/fpga/fpga-region.h
>> >> +++ b/include/linux/fpga/fpga-region.h
>> >> @@ -8,6 +8,7 @@
>> >> /**
>> >> * struct fpga_region - FPGA Region structure
>> >> * @dev: FPGA Region device
>> >> + * @parent: parent device
>> >> * @mutex: enforces exclusive reference to region
>> >> * @bridge_list: list of FPGA bridges specified in region
>> >> * @mgr: FPGA manager
>> >> @@ -18,6 +19,7 @@
>> >> */
>> >> struct fpga_region {
>> >> struct device dev;
>> >> + struct device *parent;
>> >
>> > Why doesn't your dev parent pointer point to this, why do you need to
>> > have a separate pointer? That feels really wrong. Pass in the parent
>> > pointer when you create the struct device, otherwise it will be
>> > registered incorrectly anyway. Then you always have the correct
>> > pointer, no need to keep a "spare" copy.
>>
>> I'll add a fpga_mgr_create function and let it set the parent. No
>> need to save it.
>
> I think we had discussed this in the first round of the patchset.

Yup! :)

> How about fpga_mgr_alloc(...) and fpga_mgr_register(...) as suggested
> back then?

I'm cool with either name. The alloc/create function will be doing
more than alloc. It's going to fill in some struct members, allocate
an id #, and init the dev. There's precedent for similar functions
named either way, even 'alloc' functions that do plenty of
initialization.

Alan

>
> Thanks for the review,
>
> Moritz

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