linux-kernel - RE: [PATCH v8 08/12] iommu/exynos: remove prefetch buffer setting when enabling System MMU

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Message-id: <003d01ce8c2d$c5c349d0$5149dd70$@samsung.com>
Date:	Mon, 29 Jul 2013 16:32:25 +0900
From:	Cho KyongHo <pullip.cho@...sung.com>
To:	'Grant Grundler' <grundler@...omium.org>
Cc:	'Linux ARM Kernel' <linux-arm-kernel@...ts.infradead.org>,
	'Linux IOMMU' <iommu@...ts.linux-foundation.org>,
	'Linux Kernel' <linux-kernel@...r.kernel.org>,
	'Linux Samsung SOC' <linux-samsung-soc@...r.kernel.org>,
	'Hyunwoong Kim' <khw0178.kim@...sung.com>,
	'Joerg Roedel' <joro@...tes.org>,
	'Kukjin Kim' <kgene.kim@...sung.com>,
	'Prathyush' <prathyush.k@...sung.com>,
	'Rahul Sharma' <rahul.sharma@...sung.com>,
	'Subash Patel' <supash.ramaswamy@...aro.org>,
	'Keyyoung Park' <keyyoung.park@...sung.com>,
	'Antonios Motakis' <a.motakis@...tualopensystems.com>,
	kvmarm@...ts.cs.columbia.edu,
	'Sachin Kamat' <sachin.kamat@...aro.org>
Subject: RE: [PATCH v8 08/12] iommu/exynos: remove prefetch buffer setting when
 enabling System MMU

> -----Original Message-----
> From: grundler@...gle.com [mailto:grundler@...gle.com] On Behalf Of Grant Grundler
> Sent: Saturday, July 27, 2013 2:36 AM
> 
> On Fri, Jul 26, 2013 at 4:28 AM, Cho KyongHo <pullip.cho@...sung.com> wrote:
> > Prefetch buffer must be handled accurately, exact range of a buffer,
> > frame by frame manually. Otherwise, it may causes page fault or
> > deadlock in System MMU.
> > Thus this patch removes prefetch buffer setting when System MMU is
> > initialized(enabled).
> >
> > Signed-off-by: Cho KyongHo <pullip.cho@...sung.com>
> 
> Reviewed-by: Grant Grundler <grundler@...omium.org>
> 
> BTW, cscope doesn't find any callers of exynos_sysmmu_enable().
> Want to submit another patch to remove it?
> 
> (Note I'm talking about exynos_sysmmu_enable() without "__" prefix).

Oh, I missed removing that function.

Thank you.

> 
> cheers,
> grant
> 
> > ---
> >  drivers/iommu/exynos-iommu.c |   32 +++++++++++++++++++++++++++-----
> >  1 files changed, 27 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> > index cfc02ed..87f6bb7 100644
> > --- a/drivers/iommu/exynos-iommu.c
> > +++ b/drivers/iommu/exynos-iommu.c
> > @@ -80,6 +80,8 @@
> >  #define CTRL_BLOCK     0x7
> >  #define CTRL_DISABLE   0x0
> >
> > +#define CFG_FLPDCACHE  (1 << 20) /* System MMU 3.2+ only */
> > +
> >  #define REG_MMU_CTRL           0x000
> >  #define REG_MMU_CFG            0x004
> >  #define REG_MMU_STATUS         0x008
> > @@ -96,6 +98,9 @@
> >
> >  #define REG_MMU_VERSION                0x034
> >
> > +#define MMU_MAJ_VER(reg)       (reg >> 28)
> > +#define MMU_MIN_VER(reg)       ((reg >> 21) & 0x7F)
> > +
> >  #define REG_PB0_SADDR          0x04C
> >  #define REG_PB0_EADDR          0x050
> >  #define REG_PB1_SADDR          0x054
> > @@ -200,6 +205,22 @@ static bool is_sysmmu_active(struct sysmmu_drvdata *data)
> >         return data->activations > 0;
> >  }
> >
> > +static unsigned int __sysmmu_version(struct sysmmu_drvdata *data,
> > +                                    int idx, unsigned int *minor)
> > +{
> > +       unsigned long major;
> > +
> > +       major = readl(data->sfrbases[idx] + REG_MMU_VERSION);
> > +
> > +       if (minor)
> > +               *minor = MMU_MIN_VER(major);
> > +
> > +       if (MMU_MAJ_VER(major) > 3)
> > +               return 1;
> > +
> > +       return MMU_MAJ_VER(major);
> > +}
> > +
> >  static void sysmmu_unblock(void __iomem *sfrbase)
> >  {
> >         __raw_writel(CTRL_ENABLE, sfrbase + REG_MMU_CTRL);
> > @@ -460,14 +481,15 @@ static int __exynos_sysmmu_enable(struct sysmmu_drvdata *data,
> >         data->pgtable = pgtable;
> >
> >         for (i = 0; i < data->nsfrs; i++) {
> > +               unsigned int min;
> > +
> >                 __sysmmu_set_ptbase(data->sfrbases[i], pgtable);
> >
> > -               if ((readl(data->sfrbases[i] + REG_MMU_VERSION) >> 28) == 3) {
> > -                       /* System MMU version is 3.x */
> > -                       __raw_writel((1 << 12) | (2 << 28),
> > +               if ((__sysmmu_version(data, i, &min) == 3) && (min > 1)) {
> > +                       unsigned long cfg;
> > +                       cfg = __raw_readl(data->sfrbases[i] + REG_MMU_CFG);
> > +                       __raw_writel(cfg | CFG_FLPDCACHE,
> >                                         data->sfrbases[i] + REG_MMU_CFG);
> > -                       __sysmmu_set_prefbuf(data->sfrbases[i], 0, -1, 0);
> > -                       __sysmmu_set_prefbuf(data->sfrbases[i], 0, -1, 1);
> >                 }
> >
> >                 __raw_writel(CTRL_ENABLE, data->sfrbases[i] + REG_MMU_CTRL);
> > --
> > 1.7.2.5
> >
> >

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