linux-kernel - Re: [PATCH 14/23] memory: ti-emif-pm: Fix cast to iomem pointer

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Date:   Thu, 23 Jul 2020 11:02:30 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Olof Johansson <olof@...om.net>, arm-soc <arm@...nel.org>,
        SoC Team <soc@...nel.org>, Markus Mayer <mmayer@...adcom.com>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Roger Quadros <rogerq@...com>,
        Tony Lindgren <tony@...mide.com>,
        Vladimir Zapolskiy <vz@...ia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC..." 
        <linux-mediatek@...ts.infradead.org>,
        linux-omap <linux-omap@...r.kernel.org>,
        "open list:TEGRA ARCHITECTURE SUPPORT" <linux-tegra@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH 14/23] memory: ti-emif-pm: Fix cast to iomem pointer

On Thu, Jul 23, 2020 at 10:48:19AM +0200, Arnd Bergmann wrote:
> On Thu, Jul 23, 2020 at 9:39 AM Krzysztof Kozlowski <krzk@...nel.org> wrote:
> >
> > Cast pointer to iomem memory properly to fix sparse warning:
> >
> >     drivers/memory/ti-emif-pm.c:251:38: warning: incorrect type in argument 1 (different address spaces)
> >     drivers/memory/ti-emif-pm.c:251:38:    expected void const volatile [noderef] __iomem *addr
> >     drivers/memory/ti-emif-pm.c:251:38:    got void *
> >
> > Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
> > ---
> >  drivers/memory/ti-emif-pm.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/memory/ti-emif-pm.c b/drivers/memory/ti-emif-pm.c
> > index 9c90f815ad3a..6c747c1e98cb 100644
> > --- a/drivers/memory/ti-emif-pm.c
> > +++ b/drivers/memory/ti-emif-pm.c
> > @@ -248,7 +248,7 @@ MODULE_DEVICE_TABLE(of, ti_emif_of_match);
> >  static int ti_emif_resume(struct device *dev)
> >  {
> >         unsigned long tmp =
> > -                       __raw_readl((void *)emif_instance->ti_emif_sram_virt);
> > +                       __raw_readl((void __iomem *)emif_instance->ti_emif_sram_virt);
> >
> 
> Maybe this shouldn't even be __raw_readl(), but instead READ_ONCE()?

Won't readl() be enough? Indeed it looks problematic.

> 
> The other accesses in this file don't use MMIO wrappers either but just treat
> it as a pointer. The effect would be the same though.

I think all the reads and writes are with readl() and writel().

Best regards,
Krzysztof