linux-kernel - Re: linux-next: build failure after merge of the char-misc tree

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Date:   Tue, 21 Mar 2017 11:18:02 +1100
From:   Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:     Arnd Bergmann <arnd@...db.de>,
        Stephen Rothwell <sfr@...b.auug.org.au>
Cc:     Greg KH <greg@...ah.com>, linux-next@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Cyril Bur <cyrilbur@...il.com>, Joel Stanley <joel@....id.au>
Subject: Re: linux-next: build failure after merge of the char-misc tree

On Mon, 2017-03-20 at 13:23 +0100, Arnd Bergmann wrote:
> On Mon, Mar 20, 2017 at 3:44 AM, Stephen Rothwell <sfr@...b.auug.org.au> wrote:
> > Hi all,
> > 
> > After merging the char-misc tree, today's linux-next build (x86_64
> > allmodconfig) failed like this:
> > 
> > drivers/misc/aspeed-lpc-ctrl.c: In function 'aspeed_lpc_ctrl_mmap':
> > drivers/misc/aspeed-lpc-ctrl.c:51:9: error: implicit declaration of function 'pgprot_dmacoherent' [-Werror=implicit-function-declaration]
> >   prot = pgprot_dmacoherent(prot);
> 
> A lot of other drivers (including /dev/mem) just use pgprot_noncached() or
> pgprot_writecombine(), which would make the code portable and might be
> what you want here as well.
> 
> pgprot_dmacoherent() is meant specifically for mapping RAM that is used
> for DMA buffers that come from dma_alloc_coherent(), which doesn't seem
> to be the case here.
> 
> What kind of address range is this really?

It's a piece of RAM that we reserve via a reserved region, which will
be accessed by HW (sort-of-DMA, ie, the "host" system will access that
using FW cycles on the LPC bus which we map to that reserved region of
memory).

Joel, Cyril, can you send a 1-liner patch to change that to
pgprot_noncached() ?

Cheers,
Ben.

> > drivers/misc/aspeed-lpc-ctrl.c:51:7: error: incompatible types when assigning to type 'pgprot_t {aka struct pgprot}' from type 'int'
> >   prot = pgprot_dmacoherent(prot);
> >        ^
> > In file included from include/linux/miscdevice.h:6:0,
> >                  from drivers/misc/aspeed-lpc-ctrl.c:11:
> > drivers/misc/aspeed-lpc-ctrl.c: In function 'aspeed_lpc_ctrl_probe':
> > drivers/misc/aspeed-lpc-ctrl.c:232:17: warning: format '%x' expects argument of type 'unsigned int', but argument 3 has type 'phys_addr_t {aka long long unsigned int}' [-Wformat=]
> >    dev_info(dev, "Loaded at 0x%08x (0x%08x)\n",
> 
> This should just use the "%pap" for printing a phys_addr_t, otherwise we
> get the same warning on ARM in some configurations.
> 
>       Arnd