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Subject: Re: [PATCH 1/2] fpga: dfl: add driver_override support
To:     Xu Yilun <yilun.xu@intel.com>
Cc:     mdf@kernel.org, linux-fpga@vger.kernel.org,
        linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org,
        lgoncalv@redhat.com, hao.wu@intel.com
References: <1602828151-24784-1-git-send-email-yilun.xu@intel.com>
 <1602828151-24784-2-git-send-email-yilun.xu@intel.com>
 <63d7730b-d9b8-c75d-16f6-3ebb507aabaa@redhat.com>
 <20201019040612.GA16172@yilunxu-OptiPlex-7050>
 <f767b9a0-1db8-7ced-6bd9-5ee1f58d40da@redhat.com>
 <20201020071158.GC28746@yilunxu-OptiPlex-7050>
From:   Tom Rix <trix@redhat.com>
Message-ID: <48cc1b5f-4bb1-260d-7b8b-9484d3f0a6ba@redhat.com>
Date:   Tue, 20 Oct 2020 07:13:31 -0700
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On 10/20/20 12:11 AM, Xu Yilun wrote:
>>>>>  int __dfl_driver_register(struct dfl_driver *dfl_drv, struct module *owner)
>>>>>  {
>>>>> -	if (!dfl_drv || !dfl_drv->probe || !dfl_drv->id_table)
>>>>> +	if (!dfl_drv || !dfl_drv->probe)
>>>> id_table is still needed for the normal case.
>>>>
>>>> Instead of removing this check, could you add something like
>>>>
>>>> || (!dfl_drv->is_override && !dfl_drv->id_table)
>>> I don't think it is needed. Seems is_override and !id_table are duplicated
>>> conditions for this implementation. And it may make confusing, e.g. could
>>> a driver been force matched when is_override is not set?
>>>
>>> I think we could make it simple, if the dfl driver didn't provide the
>>> id_table, normally it could not match any device. I think it could be
>>> easily understood by dfl driver developers.
>>>
>> Then an ASSERT should be added in dfl_bus_match() for id_entry.
> I didn't get your idea. What Assertion should be added for id_entry?
> BUG_ON(id_entry == NULL)? Then dfl-uio-pdev can't be inserted before
> driver_override is set.
>
> I think it is normal case that a driver is successfully registered but
> doesn't match any device because it provides no id_table.

Ok, i see your point.

Thanks for the explanation.

Tom


>
> Thanks,
> Yilun.
>