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Date: Mon, 1 Jul 2024 13:31:27 -0700
From: Rob Clark <robdclark@...il.com>
To: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
Cc: will@...nel.org, robin.murphy@....com, joro@...tes.org, jgg@...pe.ca,
jsnitsel@...hat.com, robh@...nel.org, krzysztof.kozlowski@...aro.org,
quic_c_gdjako@...cinc.com, dmitry.baryshkov@...aro.org,
konrad.dybcio@...aro.org, iommu@...ts.linux.dev,
linux-arm-msm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v13 6/6] iommu/arm-smmu: add support for PRR bit setup
On Mon, Jul 1, 2024 at 4:01 AM Bibek Kumar Patro
<quic_bibekkum@...cinc.com> wrote:
>
>
>
> On 6/28/2024 9:14 PM, Rob Clark wrote:
> > On Fri, Jun 28, 2024 at 8:10 AM Bibek Kumar Patro
> > <quic_bibekkum@...cinc.com> wrote:
> >>
> >>
> >>
> >> On 6/28/2024 7:47 PM, Rob Clark wrote:
> >>> On Fri, Jun 28, 2024 at 7:05 AM Bibek Kumar Patro
> >>> <quic_bibekkum@...cinc.com> wrote:
> >>>>
> >>>> Add an adreno-smmu-priv interface for drm/msm to call
> >>>> into arm-smmu-qcom and initiate the PRR bit setup or reset
> >>>> sequence as per request.
> >>>>
> >>>> This will be used by GPU to setup the PRR bit and related
> >>>> configuration registers through adreno-smmu private
> >>>> interface instead of directly poking the smmu hardware.
> >>>>
> >>>> Suggested-by: Rob Clark <robdclark@...il.com>
> >>>> Signed-off-by: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
> >>>> ---
> >>>> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 23 ++++++++++++++++++++++
> >>>> drivers/iommu/arm/arm-smmu/arm-smmu.h | 2 ++
> >>>> include/linux/adreno-smmu-priv.h | 6 +++++-
> >>>> 3 files changed, 30 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> >>>> index bd101a161d04..64571a1c47b8 100644
> >>>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> >>>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
> >>>> @@ -28,6 +28,7 @@
> >>>> #define PREFETCH_SHALLOW (1 << PREFETCH_SHIFT)
> >>>> #define PREFETCH_MODERATE (2 << PREFETCH_SHIFT)
> >>>> #define PREFETCH_DEEP (3 << PREFETCH_SHIFT)
> >>>> +#define GFX_ACTLR_PRR (1 << 5)
> >>>>
> >>>> static const struct actlr_config sc7280_apps_actlr_cfg[] = {
> >>>> { 0x0800, 0x04e0, PREFETCH_DEFAULT | CMTLB },
> >>>> @@ -235,6 +236,27 @@ static void qcom_adreno_smmu_resume_translation(const void *cookie, bool termina
> >>>> arm_smmu_cb_write(smmu, cfg->cbndx, ARM_SMMU_CB_RESUME, reg);
> >>>> }
> >>>>
> >>>> +static void qcom_adreno_smmu_set_prr(const void *cookie, phys_addr_t page_addr, bool set)
> >>>> +{
> >>>> + struct arm_smmu_domain *smmu_domain = (void *)cookie;
> >>>> + struct arm_smmu_cfg *cfg = &smmu_domain->cfg;
> >>>> + struct arm_smmu_device *smmu = smmu_domain->smmu;
> >>>> + u32 reg = 0;
> >>>> +
> >>>> + writel_relaxed(lower_32_bits(page_addr),
> >>>> + smmu->base + ARM_SMMU_GFX_PRR_CFG_LADDR);
> >>>> +
> >>>> + writel_relaxed(upper_32_bits(page_addr),
> >>>> + smmu->base + ARM_SMMU_GFX_PRR_CFG_UADDR);
> >>>> +
> >>>> + reg = arm_smmu_cb_read(smmu, cfg->cbndx, ARM_SMMU_CB_ACTLR);
> >>>> + reg &= ~GFX_ACTLR_PRR;
> >>>> + if (set)
> >>>> + reg |= FIELD_PREP(GFX_ACTLR_PRR, 1);
> >>>> + arm_smmu_cb_write(smmu, cfg->cbndx, ARM_SMMU_CB_ACTLR, reg);
> >>>> +
> >>>
> >>> nit, extra line
> >>>
> >>
> >> Ack, will remove this. Thanks for pointing out.
> >>
> >>> Also, if you passed a `struct page *` instead, then you could drop the
> >>> bool param, ie. passing NULL for the page would disable PRR. But I
> >>> can go either way if others have a strong preference for phys_addr_t.
> >>>
> >>
> >> Oh okay, this looks simple to reset the prr bit.
> >> But since this page is allocated and is used inside gfx driver
> >> before being utilized for prr bit operation, would it be safe for
> >> drm/gfx driver to keep a reference to this page in smmu driver?
> >>
> >> Since we only need the page address for configuring the
> >> CFG_UADDR/CFG_LADDR registers so passed the phys_addr_t.
> >
> > I don't think the smmu driver needs to keep a reference to the page..
> > we can just say it is the responsibility of the drm driver to call
> > set_prr(NULL) before freeing the page
> >
>
> That makes sense. If we go by this NULL page method to disable the PRR,
> we would have to set the address registers to reset value as well.
>
> The sequence would be like the following as per my understaning:
> - Check if it's NULL page
> - Set the PRR_CFG_UADDR/PRR_CFG_LADDR to reset values i.e - 0x0 for
> these registers
> - Reset the PRR bit in actlr register
>
> Similar to this snippet:
>
> #PRR_RESET_ADDR 0x0
>
> --------------
> reg = arm_smmu_cb_read(smmu, cfg->cbndx, ARM_SMMU_CB_ACTLR);
> reg &= ~GFX_ACTLR_PRR;
> arm_smmu_cb_write(smmu, cfg->cbndx, ARM_SMMU_CB_ACTLR, reg);
>
> if (!prr_page) {
> writel_relaxed(PRR_RESET_ADDR,
> smmu->base + ARM_SMMU_GFX_PRR_CFG_LADDR);
> writel_relaxed(PRR_RESET_ADDR),
> smmu->base + ARM_SMMU_GFX_PRR_CFG_UADDR);
> return;
> }
>
>
> writel_relaxed(lower_32_bits(page_to_phys(prr_page)),
> smmu->base + ARM_SMMU_GFX_PRR_CFG_LADDR);
>
> writel_relaxed(upper_32_bits(page_to_phys(prr_page)),
> smmu->base + ARM_SMMU_GFX_PRR_CFG_UADDR);
>
> reg |= FIELD_PREP(GFX_ACTLR_PRR, 1);
> arm_smmu_cb_write(smmu, cfg->cbndx, ARM_SMMU_CB_ACTLR, reg);
> -----------------
>
> If looks good, will implement the same in next version.
yeah, that looks like it could work..
you probably don't need to zero out the PRR_CFG_*ADDR when disabling,
and probably could avoid double writing ACTLR, but that is getting
into bikeshedding
BR,
-R
>
> Thanks & regards,
> Bibek
>
> > BR,
> > -R
> >
> >>> Otherwise, lgtm
> >>>
> >>> BR,
> >>> -R
> >>>
> >>
> >> Thanks & regards,
> >> Bibek
> >>
> >>>> +}
> >>>> +
> >>>> #define QCOM_ADRENO_SMMU_GPU_SID 0
> >>>>
> >>>> static bool qcom_adreno_smmu_is_gpu_device(struct device *dev)
> >>>> @@ -407,6 +429,7 @@ static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
> >>>> priv->get_fault_info = qcom_adreno_smmu_get_fault_info;
> >>>> priv->set_stall = qcom_adreno_smmu_set_stall;
> >>>> priv->resume_translation = qcom_adreno_smmu_resume_translation;
> >>>> + priv->set_prr = qcom_adreno_smmu_set_prr;
> >>>>
> >>>> actlrvar = qsmmu->data->actlrvar;
> >>>> if (!actlrvar)
> >>>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> >>>> index d9c2ef8c1653..3076bef49e20 100644
> >>>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
> >>>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> >>>> @@ -154,6 +154,8 @@ enum arm_smmu_cbar_type {
> >>>> #define ARM_SMMU_SCTLR_M BIT(0)
> >>>>
> >>>> #define ARM_SMMU_CB_ACTLR 0x4
> >>>> +#define ARM_SMMU_GFX_PRR_CFG_LADDR 0x6008
> >>>> +#define ARM_SMMU_GFX_PRR_CFG_UADDR 0x600C
> >>>>
> >>>> #define ARM_SMMU_CB_RESUME 0x8
> >>>> #define ARM_SMMU_RESUME_TERMINATE BIT(0)
> >>>> diff --git a/include/linux/adreno-smmu-priv.h b/include/linux/adreno-smmu-priv.h
> >>>> index c637e0997f6d..d6e2ca9f8d8c 100644
> >>>> --- a/include/linux/adreno-smmu-priv.h
> >>>> +++ b/include/linux/adreno-smmu-priv.h
> >>>> @@ -49,7 +49,10 @@ struct adreno_smmu_fault_info {
> >>>> * before set_ttbr0_cfg(). If stalling on fault is enabled,
> >>>> * the GPU driver must call resume_translation()
> >>>> * @resume_translation: Resume translation after a fault
> >>>> - *
> >>>> + * @set_prr: Extendible interface to be used by GPU to modify the
> >>>> + * ACTLR register bits, currently used to configure
> >>>> + * Partially-Resident-Region (PRR) feature's
> >>>> + * setup and reset sequence as requested.
> >>>> *
> >>>> * The GPU driver (drm/msm) and adreno-smmu work together for controlling
> >>>> * the GPU's SMMU instance. This is by necessity, as the GPU is directly
> >>>> @@ -67,6 +70,7 @@ struct adreno_smmu_priv {
> >>>> void (*get_fault_info)(const void *cookie, struct adreno_smmu_fault_info *info);
> >>>> void (*set_stall)(const void *cookie, bool enabled);
> >>>> void (*resume_translation)(const void *cookie, bool terminate);
> >>>> + void (*set_prr)(const void *cookie, phys_addr_t page_addr, bool set);
> >>>> };
> >>>>
> >>>> #endif /* __ADRENO_SMMU_PRIV_H */
> >>>> --
> >>>> 2.34.1
> >>>>
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