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Message-ID: <1615da33-a7c3-4519-b7ce-51893600034e@quicinc.com>
Date: Wed, 29 Nov 2023 14:14:32 +0530
From: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
To: Bjorn Andersson <andersson@...nel.org>
CC: <will@...nel.org>, <robin.murphy@....com>, <joro@...tes.org>,
<dmitry.baryshkov@...aro.org>, <a39.skl@...il.com>,
<konrad.dybcio@...aro.org>, <quic_bjorande@...cinc.com>,
<mani@...nel.org>, <quic_eberman@...cinc.com>,
<robdclark@...omium.org>, <u.kleine-koenig@...gutronix.de>,
<robh@...nel.org>, <vladimir.oltean@....com>,
<quic_pkondeti@...cinc.com>, <quic_molvera@...cinc.com>,
<linux-arm-msm@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>, <iommu@...ts.linux.dev>,
<linux-kernel@...r.kernel.org>, <qipl.kernel.upstream@...cinc.com>
Subject: Re: [PATCH v3 1/4] iommu/arm-smmu: introduction of ACTLR for custom
prefetcher settings
On 11/28/2023 8:31 AM, Bjorn Andersson wrote:
> On Mon, Nov 27, 2023 at 08:24:09PM +0530, Bibek Kumar Patro wrote:
>> Currently in Qualcomm SoCs the default prefetch is set to 1 which allows
>> the TLB to fetch just the next page table. MMU-500 features ACTLR
>> register which is implementation defined and is used for Qualcomm SoCs
>> to have a prefetch setting of 1/3/7/15 enabling TLB to prefetch
>
> In the previous discussion with Dmitry you stated that the "prefetch
> setting" doesn't directly map to any known values. This commit message
> give a clear indication about the meaning of these values.
>
> So, please fix the commit message to properly document the value space -
> to avoid confusion when people are searching for the meaning of the
> defines...
>
Noted, agree on the same. Thanks for pointing this out.
Will fix the description accordingly, avoid mentioning
meaning of these values.
>
> Please also clarify why there are 4 possible values here, 4 possible
> values of the 2 prefetch settings bits in the register, but only 3
> defines in the actual patch.
>
One of the values haven't been yet used in the targets whose list are
posted in this series, hence corresponding define is not mentioned in
the actual patch yet.
Thanks & Regards,
Bibek
> Regards,
> Bjorn
>
>> the next set of page tables accordingly allowing for faster translations.
>>
>> ACTLR value is unique for each SMR (Stream matching register) and stored
>> in a pre-populated table. This value is set to the register during
>> context bank initialisation.
>>
>> Signed-off-by: Bibek Kumar Patro <quic_bibekkum@...cinc.com>
>>
>> ---
>> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 56 +++++++++++++++++++++-
>> drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h | 6 ++-
>> drivers/iommu/arm/arm-smmu/arm-smmu.c | 5 +-
>> drivers/iommu/arm/arm-smmu/arm-smmu.h | 5 ++
>> 4 files changed, 68 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>> index 7f52ac67495f..4a38cae29be2 100644
>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
>> @@ -14,6 +14,12 @@
>>
>> #define QCOM_DUMMY_VAL -1
>>
>> +struct actlr_config {
>> + u16 sid;
>> + u16 mask;
>> + u32 actlr;
>> +};
>> +
>> static struct qcom_smmu *to_qcom_smmu(struct arm_smmu_device *smmu)
>> {
>> return container_of(smmu, struct qcom_smmu, smmu);
>> @@ -205,10 +211,40 @@ static bool qcom_adreno_can_do_ttbr1(struct arm_smmu_device *smmu)
>> return true;
>> }
>>
>> +static void arm_smmu_set_actlr(struct device *dev, struct arm_smmu_device *smmu, int cbndx,
>> + const struct actlr_config *actlrcfg, size_t actlrcfg_size)
>> +{
>> + struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
>> + struct arm_smmu_master_cfg *cfg = dev_iommu_priv_get(dev);
>> + struct arm_smmu_smr *smr;
>> + int i;
>> + int j;
>> + u16 id;
>> + u16 mask;
>> + int idx;
>> +
>> + for (i = 0; i < actlrcfg_size; ++i) {
>> + id = (actlrcfg + i)->sid;
>> + mask = (actlrcfg + i)->mask;
>> +
>> + for_each_cfg_sme(cfg, fwspec, j, idx) {
>> + smr = &smmu->smrs[idx];
>> + if (smr_is_subset(*smr, id, mask))
>> + arm_smmu_cb_write(smmu, cbndx, ARM_SMMU_CB_ACTLR,
>> + (actlrcfg + i)->actlr);
>> + }
>> + }
>> +}
>> +
>> static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
>> struct io_pgtable_cfg *pgtbl_cfg, struct device *dev)
>> {
>> struct adreno_smmu_priv *priv;
>> + struct arm_smmu_device *smmu = smmu_domain->smmu;
>> + struct qcom_smmu *qsmmu = to_qcom_smmu(smmu);
>> + const struct actlr_config *actlrcfg;
>> + size_t actlrcfg_size;
>> + int cbndx = smmu_domain->cfg.cbndx;
>>
>> smmu_domain->cfg.flush_walk_prefer_tlbiasid = true;
>>
>> @@ -238,6 +274,12 @@ static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain,
>> priv->set_stall = qcom_adreno_smmu_set_stall;
>> priv->resume_translation = qcom_adreno_smmu_resume_translation;
>>
>> + if (qsmmu->data->actlrcfg_gfx) {
>> + actlrcfg = qsmmu->data->actlrcfg_gfx;
>> + actlrcfg_size = qsmmu->data->actlrcfg_gfx_size;
>> + arm_smmu_set_actlr(dev, smmu, cbndx, actlrcfg, actlrcfg_size);
>> + }
>> +
>> return 0;
>> }
>>
>> @@ -263,6 +305,18 @@ static const struct of_device_id qcom_smmu_client_of_match[] __maybe_unused = {
>> static int qcom_smmu_init_context(struct arm_smmu_domain *smmu_domain,
>> struct io_pgtable_cfg *pgtbl_cfg, struct device *dev)
>> {
>> + struct arm_smmu_device *smmu = smmu_domain->smmu;
>> + struct qcom_smmu *qsmmu = to_qcom_smmu(smmu);
>> + const struct actlr_config *actlrcfg;
>> + size_t actlrcfg_size;
>> + int cbndx = smmu_domain->cfg.cbndx;
>> +
>> + if (qsmmu->data->actlrcfg) {
>> + actlrcfg = qsmmu->data->actlrcfg;
>> + actlrcfg_size = qsmmu->data->actlrcfg_size;
>> + arm_smmu_set_actlr(dev, smmu, cbndx, actlrcfg, actlrcfg_size);
>> + }
>> +
>> smmu_domain->cfg.flush_walk_prefer_tlbiasid = true;
>>
>> return 0;
>> @@ -464,7 +518,7 @@ static struct arm_smmu_device *qcom_smmu_create(struct arm_smmu_device *smmu,
>> return ERR_PTR(-ENOMEM);
>>
>> qsmmu->smmu.impl = impl;
>> - qsmmu->cfg = data->cfg;
>> + qsmmu->data = data;
>>
>> return &qsmmu->smmu;
>> }
>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
>> index 593910567b88..138fc57f7b0d 100644
>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
>> @@ -8,7 +8,7 @@
>>
>> struct qcom_smmu {
>> struct arm_smmu_device smmu;
>> - const struct qcom_smmu_config *cfg;
>> + const struct qcom_smmu_match_data *data;
>> bool bypass_quirk;
>> u8 bypass_cbndx;
>> u32 stall_enabled;
>> @@ -25,6 +25,10 @@ struct qcom_smmu_config {
>> };
>>
>> struct qcom_smmu_match_data {
>> + const struct actlr_config *actlrcfg;
>> + size_t actlrcfg_size;
>> + const struct actlr_config *actlrcfg_gfx;
>> + size_t actlrcfg_gfx_size;
>> const struct qcom_smmu_config *cfg;
>> const struct arm_smmu_impl *impl;
>> const struct arm_smmu_impl *adreno_impl;
>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> index d6d1a2a55cc0..8e4faf015286 100644
>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
>> @@ -990,9 +990,10 @@ static int arm_smmu_find_sme(struct arm_smmu_device *smmu, u16 id, u16 mask)
>> * expect simply identical entries for this case, but there's
>> * no harm in accommodating the generalisation.
>> */
>> - if ((mask & smrs[i].mask) == mask &&
>> - !((id ^ smrs[i].id) & ~smrs[i].mask))
>> +
>> + if (smr_is_subset(smrs[i], id, mask))
>> return i;
>> +
>> /*
>> * If the new entry has any other overlap with an existing one,
>> * though, then there always exists at least one stream ID
>> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
>> index 703fd5817ec1..b1638bbc41d4 100644
>> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
>> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
>> @@ -501,6 +501,11 @@ static inline void arm_smmu_writeq(struct arm_smmu_device *smmu, int page,
>> writeq_relaxed(val, arm_smmu_page(smmu, page) + offset);
>> }
>>
>> +static inline bool smr_is_subset(struct arm_smmu_smr smrs, u16 id, u16 mask)
>> +{
>> + return (mask & smrs.mask) == mask && !((id ^ smrs.id) & ~smrs.mask);
>> +}
>> +
>> #define ARM_SMMU_GR0 0
>> #define ARM_SMMU_GR1 1
>> #define ARM_SMMU_CB(s, n) ((s)->numpage + (n))
>> --
>> 2.17.1
>>
>>
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