linux-kernel - Re: [PATCH 30/30] PCI: remove pci_get_bus_and

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Message-ID: <3b1e00b6-c193-8767-ba23-8a8b3eb41e90@codeaurora.org>
Date:   Wed, 22 Nov 2017 10:18:15 -0500
From:   Sinan Kaya <okaya@...eaurora.org>
To:     Greg KH <greg@...ah.com>, Timur Tabi <timur@...eaurora.org>
Cc:     linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 30/30] PCI: remove pci_get_bus_and_slot() function

On 11/22/2017 9:49 AM, Greg KH wrote:
>>> If you have out-of-tree drivers, then yes, they can make a wrapper for
>>> this function like this if they really feel the need, or they can get
>>> their code merged:)
>> Sorry, I guess I should have been clearer.  My suggestion was to fix some of
>> the drivers where the domain can be determined, and for the rest, just mark
>> the old function as deprecated.
> So the build now gets warnings?  That's annoying, and then someone else
> will have to make the exact same patches that were created here?
> 
>> If that's still a terrible idea, well, okay.  I'm just unsure that simply
>> hard-coding a 0 for the domain for some drivers is really a solution.  Don't
>> we really want all drivers to properly support all domains?
> I bet all of those drivers don't care because they are running only in
> systems with 1 domain, otherwise they would be broken today, right?  But
> really, it shouldn't be that hard to get to the "real" PCI device to
> provide the correct pointer to the domain for most of these, as I
> pointed out in one patch review already.

I agree. Point is 95% drivers do support multiple segments. These are the
exceptions. 

We should try to fix them as much as we can. (I'll take a look at Greg's
suggestion)

In the end, this API is a backdoor and workarounds the proper APIs and
usual practices like carrying struct pci_dev pointer.

I'm trying to shoot that API in the foot so that a developer thinks twice
before putting number 0 there.

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.