lkml.org 
[lkml]   [2021]   [Feb]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v4 1/2] perf/smmuv3: Don't reserve the PMCG register spaces
From
Date
On 2021-01-30 07:14, 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.

I said my review on v3 stood either way, but for the avoidance of doubt,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

I hadn't considered that a comment is a very good idea, in case the
cleanup-script crew find this in future and try to "simplify" it :)

Thanks,
Robin.

> 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);
> + smmu_pmu->reg_base = devm_ioremap(dev, res_0->start, resource_size(res_0));
> + if (!smmu_pmu->reg_base)
> + return ERR_PTR(-ENOMEM);
>
> cfgr = readl_relaxed(smmu_pmu->reg_base + SMMU_PMCG_CFGR);
>
> /* Determine if page 1 is present */
> if (cfgr & SMMU_PMCG_CFGR_RELOC_CTRS) {
> - smmu_pmu->reloc_base = devm_platform_ioremap_resource(pdev, 1);
> - if (IS_ERR(smmu_pmu->reloc_base))
> - return PTR_ERR(smmu_pmu->reloc_base);
> + struct resource *res_1;
> +
> + res_1 = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> + if (!res_1)
> + return ERR_PTR(-EINVAL);
> + smmu_pmu->reloc_base = devm_ioremap(dev, res_1->start, resource_size(res_1));
> + if (!smmu_pmu->reloc_base)
> + return ERR_PTR(-ENOMEM);
> } else {
> smmu_pmu->reloc_base = smmu_pmu->reg_base;
> }
>

\
 
 \ /
  Last update: 2021-02-01 13:10    [W:0.089 / U:0.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site