linux-kernel - Re: [PATCH] linux/pci.h: add a dummy implement for pci_clear

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Date:   Wed, 7 Jun 2023 03:13:21 +0800
From:   Sui Jingfeng <suijingfeng@...ngson.cn>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, loongson-kernel@...ts.loongnix.cn,
        kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] linux/pci.h: add a dummy implement for pci_clear_master()

Hi,

On 2023/6/7 02:46, Bjorn Helgaas wrote:
> On Wed, Jun 07, 2023 at 01:48:38AM +0800, Sui Jingfeng wrote:
>> On 2023/6/7 00:13, Bjorn Helgaas wrote:
>>> On Tue, May 30, 2023 at 06:16:55PM +0800, Sui Jingfeng wrote:
>>>> As some arch(m68k for example) doesn't have config_pci enabled, drivers[1]
>>>> call pci_clear_master() without config_pci guard can not built.
>>>>
>>>>      drivers/gpu/drm/etnaviv/etnaviv_pci_drv.c:
>>>>      In function 'etnaviv_gpu_pci_fini':
>>>>>> drivers/gpu/drm/etnaviv/etnaviv_pci_drv.c:32:9:
>>>>      error: implicit declaration of function 'pci_clear_master';
>>>>      did you mean 'pci_set_master'? [-Werror=implicit-function-declaration]
>>>>         32 |         pci_clear_master(pdev);
>>>>            |         ^~~~~~~~~~~~~~~~
>>>>            |         pci_set_master
>>>>      cc1: some warnings being treated as errors
>>>>
>>>> [1] https://patchwork.freedesktop.org/patch/539977/?series=118522&rev=1
>>>>
>>>> Reported-by: kernel test robot <lkp@...el.com>
>>>> Closes: https://lore.kernel.org/oe-kbuild-all/202305301659.4guSLavL-lkp@intel.com/
>>>> Signed-off-by: Sui Jingfeng <suijingfeng@...ngson.cn>
>>> I applied this to pci/misc for v6.5, with commit log as below.
>>>
>>> But I suspect that it might make your life easier if you include it
>>> with your etnaviv series.  You may be able to avoid adding the
>>> CONFIG_DRM_ETNAVIV_PCI_DRIVER symbol.
>>>
>>> If so, feel free to include this patch in that series with my ack:
>>>
>>> Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
>> I do want add this tag to my all  of the patches in the drm/etnaviv series,
>> thanks.
>>
>> and I really love you this idea.
> Just to be clear, my ack only applies to the addition of the
> pci_clear_master() stub in pci.h.  It does not apply to the patches in
> the drm/etnaviv series at
> https://lore.kernel.org/r/20230603105943.3042766-1-15330273260@189.cn
Ok, I understand what you meant then.
>>> If you do include it in your series, please use the commit log below
>>> and let me know so I can drop it from my queue.
>> No, please keep this patch merged by you.
>>
>> Because this patch belong to drivers/pci, Its belong to you domain.
>>
>>
>> I might choose to  remove the CONFIG_DRM_ETNAVIV_PCI_DRIVER option at next
>> version
>>
>> of my drm/etnaviv patch If it arrived to drm/tip branch.
>>
>>
>> But I guess some reviewers may still prefer a CONFIG_DRM_ETNAVIV_PCI_DRIVER
>> option,
>>
>> depend on the attitude of etnaviv folks.
> The purpose of my ack is to enable you to merge the patch along with
> the series that uses it.  This is a normal way of handling things that
> cross subsystem boundaries, so you don't need to feel uncomfortable
> about it.
>
> It is much more difficult to remove config options than it is to add
> them, because you must ensure that the removal doesn't break old
> .config files.
>
> I will keep this patch in my queue unless you tell me to drop it.
>
> Bjorn
>
>>>     Author: Sui Jingfeng <suijingfeng@...ngson.cn>
>>>     Date:   Wed May 31 18:27:44 2023 +0800
>>>
>>>       PCI: Add pci_clear_master() stub for non-CONFIG_PCI
>>>       Add a pci_clear_master() stub when CONFIG_PCI is not set so drivers that
>>>       support both PCI and platform devices don't need #ifdefs or extra Kconfig
>>>       symbols for the PCI parts.
>>>       [bhelgaas: commit log]
>>>       Fixes: 6a479079c072 ("PCI: Add pci_clear_master() as opposite of pci_set_master()")
>>>       Link: https://lore.kernel.org/r/20230531102744.2354313-1-suijingfeng@loongson.cn
>>>       Signed-off-by: Sui Jingfeng <suijingfeng@...ngson.cn>
>>>       Reviewed-by: Geert Uytterhoeven <geert@...ux-m68k.org>
>>>       Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
>>>
>>>> ---
>>>>    include/linux/pci.h | 1 +
>>>>    1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>>>> index d0c19ff0c958..71c85380676c 100644
>>>> --- a/include/linux/pci.h
>>>> +++ b/include/linux/pci.h
>>>> @@ -1904,6 +1904,7 @@ static inline int pci_dev_present(const struct pci_device_id *ids)
>>>>    #define pci_dev_put(dev)	do { } while (0)
>>>>    static inline void pci_set_master(struct pci_dev *dev) { }
>>>> +static inline void pci_clear_master(struct pci_dev *dev) { }
>>>>    static inline int pci_enable_device(struct pci_dev *dev) { return -EIO; }
>>>>    static inline void pci_disable_device(struct pci_dev *dev) { }
>>>>    static inline int pcim_enable_device(struct pci_dev *pdev) { return -EIO; }
>>>> -- 
>>>> 2.25.1
>>>>
>> -- 
>> Jingfeng
>>
-- 
Jingfeng