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

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Date:   Thu, 31 Jan 2019 09:21:38 +0800
From:   Honghui Zhang <honghui.zhang@...iatek.com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>
CC:     Bjorn Helgaas <helgaas@...nel.org>, <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, 2019-01-30 at 16:31 +0000, Lorenzo Pieralisi wrote:
> 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.
> 

Thanks for your comments, I will send a v2 and fix all the issue you
pointed out.

> Lorenzo