Re: [PATCH v2] PCI: iproc: fix 32-bit build error

From: Bjorn Helgaas <helgaas@kernel.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Ray Jui <rjui@broadcom.com>, Hauke Mehrtens <hauke@hauke-m.de>,
	linux-arm-kernel@lists.infradead.org,
	Kevin Hilman <khilman@kernel.org>,
	Tyler Baker <tyler.baker@linaro.org>,
	lkml <linux-kernel@vger.kernel.org>,
	Olof Johansson <olof@lixom.net>, Mark Brown <broonie@kernel.org>,
	bcm-kernel-feedback-list@broadcom.com,
	Linux PCI <linux-pci@vger.kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: [PATCH v2] PCI: iproc: fix 32-bit build error
Date: Thu, 15 Oct 2015 16:01:13 -0500	[thread overview]
Message-ID: <20151015210113.GA13636@localhost> (raw)
In-Reply-To: <5754881.OPA6La0Zg0@wuerfel>

On Thu, Oct 15, 2015 at 09:40:45PM +0200, Arnd Bergmann wrote:
> The iproc PCI driver tries to figure out whether the MMIO window has
> a valid size, but does this using a 64-bit modulo operation, which
> is not allowed on 32-bit kernels and leads to a link error:
> 
> drivers/built-in.o: In function `iproc_pcie_setup':
> :(.text+0x4b798): undefined reference to `__aeabi_uldivmod'
> 
> This works around that error by using the div64_u64() function
> provided by the kernel. While this is an expensive operation,
> it is harmless because we only call it during the probing
> of the driver.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Acked-by: Ray Jui <rjui@broadcom.com>
> Fixes: 0ab99ca8eb6c ("PCI: iproc: Fix compile warnings")

This *looks* like it should be fixing 90e4032eeaf2 ("PCI: iproc: Add
outbound mapping support"), not 0ab99ca8eb6c.

90e4032eeaf2 added the "if (size % ob->window_size)".

Is this more subtle than that?

> ---
> On Thursday 15 October 2015 09:19:27 Ray Jui wrote:
> > On 10/15/2015 9:00 AM, Bjorn Helgaas wrote:
> > > 
> > > Ping; I can easily fix up the static, but it'd be nice to have real acks
> > > from Ray and Hauke.
> 
> 
> Argh, I knew there was one patch from my build fixes that I needed to
> redo, I just couldn't find it again. Thanks for the reminder.
> 
> 
> diff --git a/drivers/pci/host/pcie-iproc.c b/drivers/pci/host/pcie-iproc.c
> index f3481ddff344..9193951ae861 100644
> --- a/drivers/pci/host/pcie-iproc.c
> +++ b/drivers/pci/host/pcie-iproc.c
> @@ -241,6 +241,7 @@ static int iproc_pcie_setup_ob(struct iproc_pcie *pcie, u64 axi_addr,
>  	struct iproc_pcie_ob *ob = &pcie->ob;
>  	unsigned i;
>  	u64 max_size = (u64)ob->window_size * MAX_NUM_OB_WINDOWS;
> +	u64 remainder;
>  
>  	if (size > max_size) {
>  		dev_err(pcie->dev,
> @@ -249,7 +250,8 @@ static int iproc_pcie_setup_ob(struct iproc_pcie *pcie, u64 axi_addr,
>  		return -EINVAL;
>  	}
>  
> -	if (size % ob->window_size) {
> +	div64_u64_rem(size, ob->window_size, &remainder);
> +	if (remainder) {
>  		dev_err(pcie->dev,
>  			"res size %pap needs to be multiple of window size %pap\n",
>  			&size, &ob->window_size);
> 
> --
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