Re: [Xen-devel] [PATCH v2 03/12] xen/dt: Extend dt_device_match to possibly store data

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 27/01/15 16:46, Stefano Stabellini wrote:
> On Tue, 27 Jan 2015, Julien Grall wrote:
>> On 27/01/15 16:10, Stefano Stabellini wrote:
>>> On Tue, 27 Jan 2015, Julien Grall wrote:
>>>> Hi Stefano,
>>>>
>>>> On 27/01/15 15:57, Stefano Stabellini wrote:
>>>>>>  const struct dt_device_node *dt_get_parent(const struct dt_device_node 
>>>>>> *node)
>>>>>> diff --git a/xen/include/xen/device_tree.h 
>>>>>> b/xen/include/xen/device_tree.h
>>>>>> index 08db8bc..6502369 100644
>>>>>> --- a/xen/include/xen/device_tree.h
>>>>>> +++ b/xen/include/xen/device_tree.h
>>>>>> @@ -28,6 +28,7 @@ struct dt_device_match {
>>>>>>      const char *type;
>>>>>>      const char *compatible;
>>>>>>      const bool_t not_available;
>>>>>> +    const void *data;
>>>>>
>>>>> Why are you adding this field? It doesn't seem to be required by the
>>>>> changes to dt_match_node you are making in this patch.
>>>>
>>>> It's required for the SMMU drivers. The version of the SMMU is stored in
>>>> the field data.
>>>>
>>>> +static const struct of_device_id arm_smmu_of_match[] = {
>>>> +  { .compatible = "arm,smmu-v1", .data = (void *)ARM_SMMU_V1 },
>>>> +  { .compatible = "arm,smmu-v2", .data = (void *)ARM_SMMU_V2 },
>>>> +  { .compatible = "arm,mmu-400", .data = (void *)ARM_SMMU_V1 },
>>>> +  { .compatible = "arm,mmu-401", .data = (void *)ARM_SMMU_V1 },
>>>> +  { .compatible = "arm,mmu-500", .data = (void *)ARM_SMMU_V2 },
>>>> +  { },
>>>> +};
>>>>
>>>> The main goal of this patch is too add the field data. The change of
>>>> dt_match_node is only a side effect.
>>>
>>> In that case please make sure to write it clearly in the commit message.
>>
>> It's already on the title "xen/dt: Extend dt_device_match to possibly
>> store data" and the reason is the first line of the commit message
>> "Some drivers may want to configure differently the device depending on
>> the compatible string.".
> 
> What data? How are you extending it?

Data could be anything. I think it's enough logic to know that
dt_device_match is a structure and a new field will be added.

Regards,

-- 
Julien Grall

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