linux-kernel - Re: [PATCH] pci: brcmstb: Fix build on 32bit ARM platforms with older compilers

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Date:   Thu, 27 Feb 2020 08:09:48 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Florian Fainelli <f.fainelli@...il.com>,
        bcm-kernel-feedback-list@...adcom.com,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Andrew Murray <amurray@...goodpenguin.co.uk>
Subject: Re: [PATCH] pci: brcmstb: Fix build on 32bit ARM platforms with
 older compilers

On Thu, Feb 27, 2020 at 12:51:46PM +0100, Marek Szyprowski wrote:
> Some older compilers have no implementation for the helper for 64-bit
> unsigned division/modulo, so linking pcie-brcmstb driver causes the
> "undefined reference to `__aeabi_uldivmod'" error.
> 
> *rc_bar2_size is always a power of two, because it is calculated as:
> "1ULL << fls64(entry->res->end - entry->res->start)", so the modulo
> operation in the subsequent check can be replaced by a simple logical
> AND with a proper mask.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>

Applied to for-linus for v5.6, thanks!  I added acks from Nicolas and
Lorenzo and also the Fixes: tag from Lorenzo.

> ---
>  drivers/pci/controller/pcie-brcmstb.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> index d20aabc26273..3a10e678c7f4 100644
> --- a/drivers/pci/controller/pcie-brcmstb.c
> +++ b/drivers/pci/controller/pcie-brcmstb.c
> @@ -670,7 +670,7 @@ static inline int brcm_pcie_get_rc_bar2_size_and_offset(struct brcm_pcie *pcie,
>  	 *   outbound memory @ 3GB). So instead it will  start at the 1x
>  	 *   multiple of its size
>  	 */
> -	if (!*rc_bar2_size || *rc_bar2_offset % *rc_bar2_size ||
> +	if (!*rc_bar2_size || (*rc_bar2_offset & (*rc_bar2_size - 1)) ||
>  	    (*rc_bar2_offset < SZ_4G && *rc_bar2_offset > SZ_2G)) {
>  		dev_err(dev, "Invalid rc_bar2_offset/size: size 0x%llx, off 0x%llx\n",
>  			*rc_bar2_size, *rc_bar2_offset);
> -- 
> 2.17.1
>