Re: [PATCH 1/2] PCI: iproc: fix 32-bit build

From: Ray Jui
Date: Tue Nov 22 2016 - 12:42:53 EST




On 11/22/2016 6:17 AM, Arnd Bergmann wrote:
> The newly added code to setup the inbound ranges causes a link error
> on 32-bit machines from a 32-bit division:
>
> drivers/pci/host/pcie-iproc.o: In function `iproc_pcie_setup_ib':
> pcie-iproc.c:(.text.iproc_pcie_setup_ib+0x14c): undefined reference to `__aeabi_uldivmod'
>
> As both sides of the division are always power-of-two numbers and
> we already rely on that, we can use a shift instead.
>
> Fixes: 87c240b19bba ("PCI: iproc: Add inbound DMA mapping support")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> drivers/pci/host/pcie-iproc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/host/pcie-iproc.c b/drivers/pci/host/pcie-iproc.c
> index d10e6aa32e0d..857ff5198317 100644
> --- a/drivers/pci/host/pcie-iproc.c
> +++ b/drivers/pci/host/pcie-iproc.c
> @@ -865,7 +865,7 @@ static int iproc_pcie_ib_write(struct iproc_pcie *pcie, int region_idx,
> * Now program the IMAP registers. Each IARR region may have one or
> * more IMAP windows.
> */
> - size /= nr_windows;
> + size >>= ilog2(nr_windows);
> for (window_idx = 0; window_idx < nr_windows; window_idx++) {
> val = readl(pcie->base + imap_offset);
> val |= lower_32_bits(axi_addr) | IMAP_VALID;
>

Hmmm, somehow we've never seen this link error for the ARM32 based
platforms that we build for. Does it behave differently between
different versions of compilers?

Nevertheless, this is a good change to take, thanks!

Acked-by: Ray Jui <ray.jui@xxxxxxxxxxxx>