On Fri, Jul 16, 2021 at 3:52 PM Steven Price wrote:
>
> On 16/07/2021 09:34, Shameer Kolothum wrote:
> > From: Jon Nettleton
> >
> > Check if there is any RMR info associated with the devices behind
> > the SMMU and if any, install bypass SMRs for them. This is to
> > keep any ongoing traffic associated with these devices alive
> > when we enable/reset SMMU during probe().
> >
> > Signed-off-by: Jon Nettleton
> > Signed-off-by: Steven Price
> > Signed-off-by: Shameer Kolothum
> > ---
> > drivers/iommu/arm/arm-smmu/arm-smmu.c | 48 +++
> > 1 file changed, 48 insertions(+)
> >
> > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > index f22dbeb1e510..e9fb3d962a86 100644
> > --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > @@ -2063,6 +2063,50 @@ err_reset_platform_ops: __maybe_unused;
> > return err;
> > }
> >
> > +static void arm_smmu_rmr_install_bypass_smr(struct arm_smmu_device *smmu)
> > +{
> > + struct list_head rmr_list;
> > + struct iommu_resv_region *e;
> > + int i, cnt = 0;
> > + u32 reg;
> > +
> > + INIT_LIST_HEAD(_list);
> > + if (iommu_dma_get_rmrs(dev_fwnode(smmu->dev), _list))
> > + return;
> > +
> > + /*
> > + * Rather than trying to look at existing mappings that
> > + * are setup by the firmware and then invalidate the ones
> > + * that do no have matching RMR entries, just disable the
> > + * SMMU until it gets enabled again in the reset routine.
> > + */
> > + reg = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_sCR0);
> > + reg &= ~ARM_SMMU_sCR0_CLIENTPD;
>
> This looks backwards, the spec states:
>
> Client Port Disable. The possible values of this bit are:
> 0 - Each SMMU client access is subject to SMMU translation, access
> control, and attribute generation.
> 1 - Each SMMU client access bypasses SMMU translation, access control,
> and attribute generation.
> This bit resets to 1.
>
> And indeed with the current code if sCR0_USFCFG was set when
> sCR0_CLIENTPD is cleared then I get a blank screen until the smmu is reset.
>
> So I believe this should be ORing in the value, i.e.
>
> reg |= ARM_SMMU_sCR0_CLIENTPD;
>
> And in my testing that works fine even if sCR0_USFCFG is set.
Sorry that is my bad. It was a hurried and sloppy copy paste on my part.
Thanks for catching it
-Jon
>
> Steve
>
> > + arm_smmu_gr0_write(smmu, ARM_SMMU_GR0_sCR0, reg);
> > +
> > + list_for_each_entry(e, _list, list) {
> > + u32 sid = e->fw_data.rmr.sid;
> > +
> > + i = arm_smmu_find_sme(smmu, sid, ~0);
> > + if (i < 0)
> > + continue;
> > + if (smmu->s2crs[i].count == 0) {
> > + smmu->smrs[i].id = sid;
> > + smmu->smrs[i].mask = 0;
> > + smmu->smrs[i].valid = true;
> > + }
> > + smmu->s2crs[i].count++;
> > + smmu->s2crs[i].type = S2CR_TYPE_BYPASS;
> > + smmu->s2crs[i].privcfg = S2CR_PRIVCFG_DEFAULT;
> > +
> > + cnt++;
> > + }
> > +
> > + dev_notice(smmu->dev, "\tpreserved %d boot mapping%s\n", cnt,
> > +cnt == 1 ? "" : "s");
> > + iommu_dma_put_rmrs(dev_fwnode(smmu->dev), _list);
> > +}
> > +
> > static int arm_smmu_device_probe(struct platform_device *pdev)
> > {
> > struct resource *res;
> > @@ -2189,6 +2233,10 @@ static int arm_smmu_device_probe(struct
> > platform_device *pdev)
> > }
> >
> > platform_set_drvdata(pdev, smmu);
> > +
> > + /* Check for RMRs and install bypass SMRs if any */
> > + arm_smmu_rmr_install_bypass_smr(smmu);
> > +
> > arm_smmu_device_reset(smmu);
> > arm_smmu_test_smr_masks(smmu);
> >
> >
>
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