Re: [PATCH v2 1/2] PCI: mediatek: Use resource_size function on resource object
From: Bjorn Helgaas <helgaas@kernel.org>
Date: 2019-01-31 21:36:54
Also in:
linux-mediatek, linux-pci, lkml
On Thu, Jan 31, 2019 at 04:01:52PM +0800, honghui.zhang@mediatek.com wrote:
From: Honghui Zhang <redacted> scripts/coccinelle/api/resource_size.cocci complain about the following warning: pcie-mediatek.c:720:13-16: WARNING: Suspicious code. resource_size is maybe missing with mem Use resource_size(mem) instead of mem->end - mem->start to eliminate the complain. Since the MMIO window size for both MT2712 and MT7622 are all 0x1000_0000, this change also fix the AHB2PCIe window size smaller than HW MMIO window size issue by change the values of fls(size) from fls(0xfff_ffff) to fls(0x1000_0000).
Good, I'm glad this actually fixes a bug. The warning was actually useful! Since that's the case, the *bug* is the important thing (not the warning), and the subject line should be about the bug fix. The fact that it also happens to remove a warning is really just incidental. You say "the AHB2PCIe window size smaller than HW MMIO window size issue" as though it should be familiar to us. But it's not :) So the changelog needs to start by explaining what the AHB2PCIe window size issue is, mention what user-visible problem that causes, then explain how you're fixing it by using resource_size(). Then you can mention that this also incidentally removes a coccinelle warning. Bjorn
quoted hunk ↗ jump to hunk
Signed-off-by: Honghui Zhang <redacted> --- drivers/pci/controller/pcie-mediatek.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c index 55e471c..01126b8 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 +705,8 @@ 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)));
Nit: I think it's more typical to put the "|" on the first line.
writel(val, port->base + PCIE_AHB_TRANS_BASE0_L); val = upper_32_bits(mem->start); -- 2.6.4 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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