linux-kernel - Re: [PATCH] PCI: Mediatek: Use resource

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Message-ID: <20190130163155.GA5847@e107981-ln.cambridge.arm.com>
Date:   Wed, 30 Jan 2019 16:31:55 +0000
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     honghui.zhang@...iatek.com, youlin.pei@...iatek.com,
        ryder.lee@...iatek.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, jianjun.wang@...iatek.com,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] PCI: Mediatek: Use resource_size function on resource
 object

On Wed, Jan 30, 2019 at 09:58:53AM -0600, Bjorn Helgaas wrote:
> On Wed, Jan 30, 2019 at 12:33:47PM +0000, Lorenzo Pieralisi wrote:
> > On Wed, Jan 02, 2019 at 02:03:53PM +0800, honghui.zhang@...iatek.com wrote:
> > > From: Honghui Zhang <honghui.zhang@...iatek.com>
> > > 
> > > 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@...iatek.com>
> > > ---
> > >  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)));
> > 
> > checkpatch warns on this line, please make sure patches pass it before
> > posting them.
> 
> I didn't actually run checkpatch myself, so I don't know why it
> complained.

WARNING: line over 80 characters
#35: FILE: drivers/pci/controller/pcie-mediatek.c:708:
+	val = lower_32_bits(mem->start) | AHB2PCIE_SIZE(fls(resource_size(mem)));

I do run it as a sanity check.

> The patch you merged moves "mem_size = resource_size(mem)" higher up,
> away from the previous location and its use, which makes it a little
> harder to read.

That's because it was how the original code (which as you pointed out
is likely buggy) was written.

Anyway patch dropped waiting for a v2 consistent with your review -
apologies for missing some key review points.

Lorenzo