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Date: Fri, 28 Jun 2024 19:41:26 +0530
From: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
To: Rob Clark <robdclark@...il.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 v11 6/6] iommu/arm-smmu: add support for PRR bit setup
On 6/27/2024 12:16 AM, Rob Clark wrote:
> On Thu, Jun 13, 2024 at 1:11 AM Bibek Kumar Patro
> <quic_bibekkum@...cinc.com> wrote:
>>
>>
>>
>> On 6/12/2024 12:32 AM, Rob Clark wrote:
>>> On Wed, Jun 5, 2024 at 5:18 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 side to setup the PRR bit and
>>>> related configuration registers through adreno-smmu private
>>>> interface instead of directly poking the smmu hardware.
>>>>
>>>> Signed-off-by: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
>>>> ---
>>>> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 21 +++++++++++++++++++++
>>>> drivers/iommu/arm/arm-smmu/arm-smmu.h | 2 ++
>>>> include/linux/adreno-smmu-priv.h | 5 ++++-
>>>> 3 files changed, 27 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 8dabc26fa10e..2f4ee22f740a 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, 0x24e1, PREFETCH_DEFAULT | CMTLB },
>>>> @@ -212,6 +213,25 @@ 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_actlr_bit(const void *cookie, phys_addr_t page_addr, bool set)
>>>> +{
>>>
>>> _set_actlr_bit() is a bit more of an implementation detail. Maybe
>>> _set_prr() would be a better name?
>>>
>>
>> Yes set_prr sounds more explanatory. Infact Initially planned to name it
>> as set_actlr_prr() but later changed it to set_actlr_bit() so to keep
>> this interface extendible.
>> Incase if gfx driver in future wants to control some other ACTLR bit as
>> well along with PRR bit, then we can extend this same interface to
>> handle other bits.
>> So any additional adreno-smmu-priv interface would note be needed, and
>> set_actlr_bit can itself be used for gfx handling of all required ACTLR
>> bits.
>> I think we can name it set_actlr_prr() for now, and later can change the
>> name incase we extend it. What's your thought on this?
>
> I think set_prr() or set_acltr_prr() is fine.. we can worry about
> making it more generic if and when there are other ACLTR bits the gpu
> wants to control
>
Ack, sounds good to me as well. I've used set_prr() for now.
>>> Also, the version of this patch that I typed up (but haven't sent to
>>> list yet) took a `struct page *` instead of a phys_addr_t.. passing
>>> NULL would disable PRR, so I didn't need the third arg
>>>
>>>> + 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),
>>>> + (void *)smmu->ioaddr + ARM_SMMU_GFX_PRR_CFG_LADDR);
>>>> +
>>>> + writel_relaxed(upper_32_bits(page_addr),
>>>> + (void *)smmu->ioaddr + ARM_SMMU_GFX_PRR_CFG_UADDR);
>>>
>>> I know downstream writes it as upper+lower, but I'd guess we could
>>> just writeq, couldn't we?
>>>
>>
>> Actually ARM_SMMU_GFX_PRR_CFG_LADDR, ARM_SMMU_GFX_PRR_CFG_UADDR both are
>> separate 32 bit registers. So I think writeq for 64bit write might not
>> work, as these are not 64 bit registers nor these two are separated by
>> 64 aligned address.
>
> ahh, ok
>
>>>> +
>>>> + reg = arm_smmu_cb_read(smmu, cfg->cbndx, ARM_SMMU_CB_ACTLR);
>>>> + reg |= FIELD_PREP(GFX_ACTLR_PRR, set ? 1 : 0);
>>>
>>> this won't clear the ENABLE_PRR bit if we try to disable it after
>>> enabling (unless this bit is read-as-zero
>>>
>>
>> Ah okay right, got it. Thanks for pointing this out.
>> Will take care of this in next version.
>> will use set/reset in side if() instead with different
>> bitwise ops for set and reset.
>>
>>
>>> Also, can we give a name to PRR? I'm guessing it is something like
>>> physical-range-remap?
>>
>> Yes sure. I checked on this, PRR here actually stands for
>> partially-resident-region.
>
> ahh, ok, that makes sense
>
>> So would be better If we add expansion for PRR in a comment ?
>> Because if we expand PRR in variables/defines then wouldn't
>> the names become too long?
>
> Yeah, I was just thinking to mention it in the comment for set_prr()
>
Yes, that seemed to be an appropriate place to add the expansion.
Mentioned it in the comment for now.
Thanks & regards,
Bibek
> BR,
> -R
>
>>
>> Thanks & regards,
>> Bibek
>>
>>>
>>> BR,
>>> -R
>>>
>>>> + arm_smmu_cb_write(smmu, cfg->cbndx, ARM_SMMU_CB_ACTLR, reg);
>>>> +
>>>> +}
>>>> +
>>>> #define QCOM_ADRENO_SMMU_GPU_SID 0
>>>>
>>>> static bool qcom_adreno_smmu_is_gpu_device(struct device *dev)
>>>> @@ -384,6 +404,7 @@ 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_actlr_bit = qcom_adreno_smmu_set_actlr_bit;
>>>>
>>>> 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..448e191eeb52 100644
>>>> --- a/include/linux/adreno-smmu-priv.h
>>>> +++ b/include/linux/adreno-smmu-priv.h
>>>> @@ -49,7 +49,9 @@ 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_actlr_bits: Extendible interface to be used by GPU to modify the
>>>> + * ACTLR bits, currently used to intitate PRR bit setup or
>>>> + * reset sequence for ACTLR registers 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 +69,7 @@ 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_actlr_bit)(const void *cookie, phys_addr_t page_addr, bool set);
>>>> };
>>>>
>>>> #endif /* __ADRENO_SMMU_PRIV_H */
>>>> --
>>>> 2.34.1
>>>>
>
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