Re: [PATCH v16 3/5] iommu/arm-smmu: add support for PRR bit setup

[Bibek Kumar Patro <quic_bibekkum@quicinc.com>]

On 10/29/2024 6:59 PM, Robin Murphy wrote:
> On 2024-10-08 1:54 pm, Bibek Kumar Patro 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@gmail.com>
>> Signed-off-by: Bibek Kumar Patro <quic_bibekkum@quicinc.com>
>> ---
>>   drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 37 ++++++++++++++++++++++
>>   drivers/iommu/arm/arm-smmu/arm-smmu.h      |  2 ++
>>   include/linux/adreno-smmu-priv.h           | 10 +++++-
>>   3 files changed, 48 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 6e0a2a43e45a..38ac9cab763b 100644
>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>> @@ -25,6 +25,7 @@
>>
>>   #define CPRE            (1 << 1)
>>   #define CMTLB            (1 << 0)
>> +#define GFX_ACTLR_PRR        (1 << 5)
>>
>>   static struct qcom_smmu *to_qcom_smmu(struct arm_smmu_device *smmu)
>>   {
>> @@ -109,6 +110,40 @@ 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_bit(const void *cookie, bool set)
>> +{
>> +    struct arm_smmu_domain *smmu_domain = (void *)cookie;
>> +    struct arm_smmu_device *smmu = smmu_domain->smmu;
>> +    const struct device_node *np = smmu->dev->of_node;
>> +    struct arm_smmu_cfg *cfg = &smmu_domain->cfg;
>> +    u32 reg = 0;
>> +
>> +    if (of_device_is_compatible(np, "qcom,smmu-500") &&
>> +            of_device_is_compatible(np, "qcom,adreno-smmu")) {
> 
> These conditions aren't going to change between calls - wouldn't it make 
> more sense to conditionally assign the callbacks in the first place? Not 
> the biggest deal if this is a one-off context-setup type thing, just 
> that it looks a little funky.
> 

Let me know if you want to pursue this still.
 From the current PRR implementation in the graphics
vendor layer, this seems to be just setup kind-of thing.
Also if we keep this conditional check before assigning callbacks,
and vendor layer caller won't be having any such check,
wouldn't it be an issue in unsupported platforms (!qcom,smmu-500 or 
!qcom,adreno-smmu)
as the callbacks won't be assigned?
So as per my understanding I think it would be safe to keep the 
condition check here?

Thanks & regards,
Bibek


> Thanks,
> Robin.
> 
>> +        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);
>> +    }
>> +}
>> +
>> +static void qcom_adreno_smmu_set_prr_addr(const void *cookie, 
>> phys_addr_t page_addr)
>> +{
>> +    struct arm_smmu_domain *smmu_domain = (void *)cookie;
>> +    struct arm_smmu_device *smmu = smmu_domain->smmu;
>> +    const struct device_node *np = smmu->dev->of_node;
>> +
>> +    if (of_device_is_compatible(np, "qcom,smmu-500") &&
>> +            of_device_is_compatible(np, "qcom,adreno-smmu")) {
>> +        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);
>> +    }
>> +}
>> +
>>   #define QCOM_ADRENO_SMMU_GPU_SID 0
>>
>>   static bool qcom_adreno_smmu_is_gpu_device(struct device *dev)
>> @@ -249,6 +284,8 @@ 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_bit = qcom_adreno_smmu_set_prr_bit;
>> +    priv->set_prr_addr = qcom_adreno_smmu_set_prr_addr;
>>
>>       return 0;
>>   }
>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/ 
>> arm/arm-smmu/arm-smmu.h
>> index e2aeb511ae90..2dbf3243b5ad 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..03466eb16933 100644
>> --- a/include/linux/adreno-smmu-priv.h
>> +++ b/include/linux/adreno-smmu-priv.h
>> @@ -49,7 +49,13 @@ 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_bit:   Extendible interface to be used by GPU to modify the
>> + *           ACTLR register bits, currently used to configure
>> + *           Partially-Resident-Region (PRR) bit for feature's
>> + *           setup and reset sequence as requested.
>> + * @set_prr_addr:  Configure the PRR_CFG_*ADDR register with the
>> + *           physical address of PRR page passed from
>> + *           GPU driver.
>>    *
>>    * 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 +73,8 @@ 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_bit)(const void *cookie, bool set);
>> +    void (*set_prr_addr)(const void *cookie, phys_addr_t page_addr);
>>   };
>>
>>   #endif /* __ADRENO_SMMU_PRIV_H */
>> -- 
>> 2.34.1
>>