linux-kernel - Re: [PATCH v1] PCI: brcmstb: variable is missing proper initialization

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Date:   Wed, 4 Nov 2020 09:48:06 -0500
From:   Jim Quinlan <james.quinlan@...adcom.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     "open list:PCI NATIVE HOST BRIDGE AND ENDPOINT DRIVERS" 
        <linux-pci@...r.kernel.org>,
        "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <bcm-kernel-feedback-list@...adcom.com>,
        Rafał Miłecki <zajec5@...il.com>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Murray <amurray@...goodpenguin.co.uk>,
        Jeremy Linton <jeremy.linton@....com>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@...ts.infradead.org>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] PCI: brcmstb: variable is missing proper initialization

On Tue, Nov 3, 2020 at 2:38 PM Bjorn Helgaas <helgaas@...nel.org> wrote:
>
> On Mon, Nov 02, 2020 at 03:57:12PM -0500, Jim Quinlan wrote:
> > The variable 'tmp' is used multiple times in the brcm_pcie_setup()
> > function.  One such usage did not initialize 'tmp' to the current value of
> > the target register.  By luck the mistake does not currently affect
> > behavior;  regardless 'tmp' is now initialized properly.
>
> This is so trivial that there's probably no reason to post this again,
> but if you post a v2 for some reason, please update the subject to
> match the convention ("PCI: brcmstb: Verb ..."), e.g.,
>
>   PCI: brcmstb: Initialize "tmp" before use
>
> The commit log does not say what the patch does, leaving it to the
> reader to infer it.

Got it.
Thanks,
Jim Quinlan
Broadcom STB
>
>
>
>
> Lorenzo will likely fix this up when he applies it.
>
> Incidental curiosity: where should I look to see what
> u32p_replace_bits() does?  "git grep u32p_replace_bits" shows several
> calls, but no definitions.
>
> > Fixes: c0452137034b ("PCI: brcmstb: Add Broadcom STB PCIe host controller driver")
> > Suggested-by: Rafał Miłecki <zajec5@...il.com>
> > Signed-off-by: Jim Quinlan <james.quinlan@...adcom.com>
> > ---
> >  drivers/pci/controller/pcie-brcmstb.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> > index bea86899bd5d..9c3d2982248d 100644
> > --- a/drivers/pci/controller/pcie-brcmstb.c
> > +++ b/drivers/pci/controller/pcie-brcmstb.c
> > @@ -893,6 +893,7 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
> >               burst = 0x2; /* 512 bytes */
> >
> >       /* Set SCB_MAX_BURST_SIZE, CFG_READ_UR_MODE, SCB_ACCESS_EN */
> > +     tmp = readl(base + PCIE_MISC_MISC_CTRL);
> >       u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_SCB_ACCESS_EN_MASK);
> >       u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_CFG_READ_UR_MODE_MASK);
> >       u32p_replace_bits(&tmp, burst, PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_MASK);
> > --
> > 2.17.1
> >
>
>

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