On Wed, 2019-01-30 at 09:49 -0600, Bjorn Helgaas wrote: > On Wed, Jan 02, 2019 at 02:03:53PM +0800, honghui.zhang@xxxxxxxxxxxx wrote: > > From: Honghui Zhang <honghui.zhang@xxxxxxxxxxxx> > > > > drivers/pci/pcie-mediatek.c:720:13-16: WARNING: Suspicious code. resource_size is maybe missing with mem > > > > Generated by: scripts/coccinelle/api/resource_size.cocci > > > > Signed-off-by: Honghui Zhang <honghui.zhang@xxxxxxxxxxxx> > > --- > > drivers/pci/controller/pcie-mediatek.c | 4 +--- > > 1 file changed, 1 insertion(+), 3 deletions(-) > > > > diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c > > index e307166..0168376 100644 > > --- a/drivers/pci/controller/pcie-mediatek.c > > +++ b/drivers/pci/controller/pcie-mediatek.c > > @@ -654,7 +654,6 @@ static int mtk_pcie_startup_port_v2(struct mtk_pcie_port *port) > > struct resource *mem = &pcie->mem; > > const struct mtk_pcie_soc *soc = port->pcie->soc; > > u32 val; > > - size_t size; > > int err; > > > > /* MT7622 platforms need to enable LTSSM and ASPM from PCIe subsys */ > > @@ -706,8 +705,7 @@ static int mtk_pcie_startup_port_v2(struct mtk_pcie_port *port) > > mtk_pcie_enable_msi(port); > > > > /* Set AHB to PCIe translation windows */ > > - size = mem->end - mem->start; > > - val = lower_32_bits(mem->start) | AHB2PCIE_SIZE(fls(size)); > > + val = lower_32_bits(mem->start) | AHB2PCIE_SIZE(fls(resource_size(mem))); > > This is actually a fairly interesting change because it effectively > changes this: > > fls(mem->end - mem->start) > > to this: > > fls(mem->end - mem->start + 1) > > And mem->end is the last valid address, so it changes something like > this: > > fls(0xffff) # == 15 > > to this: > > fls(0x10000) # == 16 > > So while this *looks* like a trivial warning fix, it likely fixes an > important bug, and it's worth pointing out what that bug is in the > changelog. > > > writel(val, port->base + PCIE_AHB_TRANS_BASE0_L); > > > > val = upper_32_bits(mem->start); This size will set the MMIO size, which means that the RC will translate the MMIO access from mem->start to mem->end. The real MMIO size is specified in devicetree, which is 0x1000_0000 for both mt2712 and mt7622. This change make the size from fls(0x1000_0000) to fls(0x1000_0001), not really change the values. I will update the commit message and add the information mentioned above. Thanks for your kindly review. > > -- > > 2.6.4 > >
