Re: [PATCH v4 1/2] perf/smmuv3: Don't reserve the PMCG register spaces

["Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>]

On 2021/2/1 20:54, Will Deacon wrote:
> On Sat, Jan 30, 2021 at 03:14:13PM +0800, Zhen Lei wrote:
>> According to the SMMUv3 specification:
>> Each PMCG counter group is represented by one 4KB page (Page 0) with one
>> optional additional 4KB page (Page 1), both of which are at IMPLEMENTATION
>> DEFINED base addresses.
>>
>> This means that the PMCG register spaces may be within the 64KB pages of
>> the SMMUv3 register space. When both the SMMU and PMCG drivers reserve
>> their own resources, a resource conflict occurs.
>>
>> To avoid this conflict, don't reserve the PMCG regions.
>>
>> Suggested-by: Robin Murphy <robin.murphy@arm.com>
>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
>> ---
>>  drivers/perf/arm_smmuv3_pmu.c | 25 +++++++++++++++++++------
>>  1 file changed, 19 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
>> index 74474bb322c3f26..5e894f957c7b935 100644
>> --- a/drivers/perf/arm_smmuv3_pmu.c
>> +++ b/drivers/perf/arm_smmuv3_pmu.c
>> @@ -793,17 +793,30 @@ static int smmu_pmu_probe(struct platform_device *pdev)
>>  		.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
>>  	};
>>  
>> -	smmu_pmu->reg_base = devm_platform_get_and_ioremap_resource(pdev, 0, &res_0);
>> -	if (IS_ERR(smmu_pmu->reg_base))
>> -		return PTR_ERR(smmu_pmu->reg_base);
>> +	/*
>> +	 * The register spaces of the PMCG may be in the register space of
>> +	 * other devices. For example, SMMU. Therefore, the PMCG resources are
>> +	 * not reserved to avoid resource conflicts with other drivers.
>> +	 */
>> +	res_0 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	if (!res_0)
>> +		return ERR_PTR(-EINVAL);
> 
> I tried to apply this, but you've got your return type in a muddle:

I'm dizzy. I don't know how this bug patch came out. I just pinched my leg, like I'm still in the real world.

The "ERR_PTR()" of the four ERR_PTR(xxx) should be removed. Can you help me? Or I send a new one.

> 
> @@ @@
> +drivers/perf/arm_smmuv3_pmu.c: In function ‘smmu_pmu_probe’:
> +drivers/perf/arm_smmuv3_pmu.c:803:10: warning: returning ‘void *’ from a function with return type ‘int’ makes integer from pointer without a cast [-Wint-conversion]
> +  803 |   return ERR_PTR(-EINVAL);
> +      |          ^~~~~~~~~~~~~~~~
> +drivers/perf/arm_smmuv3_pmu.c:803:31: warning: incorrect type in return expression (different base types) [sparse]
> +drivers/perf/arm_smmuv3_pmu.c:803:31:    expected int [sparse]
> +drivers/perf/arm_smmuv3_pmu.c:803:31:    got void * [sparse]
> +drivers/perf/arm_smmuv3_pmu.c:806:10: warning: returning ‘void *’ from a function with return type ‘int’ makes integer from pointer without a cast [-Wint-conversion]
> +  806 |   return ERR_PTR(-ENOMEM);
> +      |          ^~~~~~~~~~~~~~~~
> +drivers/perf/arm_smmuv3_pmu.c:806:31: warning: incorrect type in return expression (different base types) [sparse]
> +drivers/perf/arm_smmuv3_pmu.c:806:31:    expected int [sparse]
> +drivers/perf/arm_smmuv3_pmu.c:806:31:    got void * [sparse]
> +drivers/perf/arm_smmuv3_pmu.c:816:11: warning: returning ‘void *’ from a function with return type ‘int’ makes integer from pointer without a cast [-Wint-conversion]
> +  816 |    return ERR_PTR(-EINVAL);
> +      |           ^~~~~~~~~~~~~~~~
> +drivers/perf/arm_smmuv3_pmu.c:816:39: warning: incorrect type in return expression (different base types) [sparse]
> +drivers/perf/arm_smmuv3_pmu.c:816:39:    expected int [sparse]
> +drivers/perf/arm_smmuv3_pmu.c:816:39:    got void * [sparse]
> +drivers/perf/arm_smmuv3_pmu.c:819:11: warning: returning ‘void *’ from a function with return type ‘int’ makes integer from pointer without a cast [-Wint-conversion]
> +  819 |    return ERR_PTR(-ENOMEM);
> +      |           ^~~~~~~~~~~~~~~~
> +drivers/perf/arm_smmuv3_pmu.c:819:39: warning: incorrect type in return expression (different base types) [sparse]
> +drivers/perf/arm_smmuv3_pmu.c:819:39:    expected int [sparse]
> +drivers/perf/arm_smmuv3_pmu.c:819:39:    got void * [sparse]
> 
> Will
> 
> .
> 

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