linux-kernel - Re: [PATCH 3/3] bus: hisi_lpc: Expand build test coverage

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Message-ID: <CAK8P3a2LZnDfT_yNaDo4CgheC-1dZvK3DMrC8RY6qt4F6rEGvg@mail.gmail.com>
Date:   Wed, 2 Oct 2019 20:22:54 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     John Garry <john.garry@...wei.com>
Cc:     Wei Xu <xuwei5@...ilicon.com>, Linuxarm <linuxarm@...wei.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Olof Johansson <olof@...om.net>
Subject: Re: [PATCH 3/3] bus: hisi_lpc: Expand build test coverage

On Wed, Oct 2, 2019 at 6:25 PM John Garry <john.garry@...wei.com> wrote:
> On 02/10/2019 16:43, Arnd Bergmann wrote:
> > On Tue, Oct 1, 2019 at 6:07 PM John Garry <john.garry@...wei.com> wrote:
> >>
> >> Currently the driver will only ever be built for ARM64 because it selects
> >> CONFIG_INDIRECT_PIO, which itself depends on ARM64.
> >>
> >> Expand build test coverage for the driver to other architectures by only
> >> selecting CONFIG_INDIRECT_PIO for ARM64, when we really want it.
> >>
> >> Signed-off-by: John Garry <john.garry@...wei.com>
> >
>
> Hi Arnd,
>
> > Good idea, but doesn't this cause a link failure against
> > logic_pio_register_range() when INDIRECT_PIO is disabled?
>
> No, it shouldn't do. Function
> lib/logic_pio.c::logic_pio_register_range() is built always, outside any
> INDIRECT_PIO checking.

Ok, I see.

> A some stage, for completeness we should probably change
> logic_pio_register_range() and friends to be under PCI_IOBASE. But then
> we would need stubs for !PCI_IOBASE, due to this above change and also
> references from the device tree code. I'd have to consider this a bit
> more. Let me know what you think.

It's probably not to do this with the usual 'static inline' stubs in the
header files. There is no rush here, but it would be nice to not build
this code when it is not needed.

I wonder if this one-line change would take care of the !CONFIG_OF
case already (it probably doesn't):

--- a/lib/Makefile
+++ b/lib/Makefile
@@ -107,7 +107,7 @@ obj-$(CONFIG_HAS_IOMEM) += iomap_copy.o devres.o
 obj-$(CONFIG_CHECK_SIGNATURE) += check_signature.o
 obj-$(CONFIG_DEBUG_LOCKING_API_SELFTESTS) += locking-selftest.o

-obj-y += logic_pio.o
+lib-y += logic_pio.o

 obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o

On a related note: At some point we may want to add an indirect
method for readl()/writel(), to deal with some of the weirder 32-bit
ARM platforms. We'll have to see how well this can fit into the
infrastructure we already have for indirect PIO.

     Arnd