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

From: Hauke Mehrtens <hauke@hauke-m.de>
To: Arnd Bergmann <arnd@arndb.de>, linux-arm-kernel@lists.infradead.org
Cc: Kevin Hilman <khilman@kernel.org>, Ray Jui <rjui@broadcom.com>,
	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] PCI: iproc: fix 32-bit build error
Date: Tue, 13 Oct 2015 22:06:48 +0200	[thread overview]
Message-ID: <561D6458.40504@hauke-m.de> (raw)
In-Reply-To: <11199595.GgDE2yo8AA@wuerfel>

On 10/13/2015 10:02 PM, 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>
> Fixes: 0ab99ca8eb6c ("PCI: iproc: Fix compile warnings")
> 
> diff --git a/drivers/pci/host/pcie-iproc.c b/drivers/pci/host/pcie-iproc.c
> index f3481ddff344..abcb4be2ee19 100644
> --- a/drivers/pci/host/pcie-iproc.c
> +++ b/drivers/pci/host/pcie-iproc.c
> @@ -235,12 +235,13 @@ static void iproc_pcie_enable(struct iproc_pcie *pcie)
>   *
>   * axi_addr -> iproc_pcie_address -> OARR -> OMAP -> pci_address
>   */
> -static int iproc_pcie_setup_ob(struct iproc_pcie *pcie, u64 axi_addr,
> +int iproc_pcie_setup_ob(struct iproc_pcie *pcie, u64 axi_addr,

Why are you removing the static here?

>  			       u64 pci_addr, resource_size_t size)
>  {
>  	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);
> 