On Tue, 28 May 2024 at 19:08, Rob Clark <robdclark@xxxxxxxxx> wrote: > > On Tue, May 28, 2024 at 6:06 AM Dmitry Baryshkov > <dmitry.baryshkov@xxxxxxxxxx> wrote: > > > > On Tue, May 28, 2024 at 02:59:51PM +0200, Konrad Dybcio wrote: > > > > > > > > > On 5/15/24 15:59, Bibek Kumar Patro wrote: > > > > > > > > > > > > On 5/10/2024 6:32 PM, Konrad Dybcio wrote: > > > > > On 10.05.2024 2:52 PM, Bibek Kumar Patro wrote: > > > > > > > > > > > > > > > > > > On 5/1/2024 12:30 AM, Rob Clark wrote: > > > > > > > On Tue, Jan 23, 2024 at 7:00 AM Bibek Kumar Patro > > > > > > > <quic_bibekkum@xxxxxxxxxxx> 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 custom prefetch setting enabling TLB to prefetch 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@xxxxxxxxxxx> > > > > > > > > --- > > > > > > > > > > [...] > > > > > > > > > > > > > + > > > > > > > > + 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); > > > > > > > > > > > > > > So, this makes ACTLR look like kind of a FIFO. But I'm looking at > > > > > > > downstream kgsl's PRR thing (which we'll need to implement vulkan > > > > > > > sparse residency), and it appears to be wanting to set BIT(5) in ACTLR > > > > > > > to enable PRR. > > > > > > > > > > > > > > val = KGSL_IOMMU_GET_CTX_REG(ctx, KGSL_IOMMU_CTX_ACTLR); > > > > > > > val |= FIELD_PREP(KGSL_IOMMU_ACTLR_PRR_ENABLE, 1); > > > > > > > KGSL_IOMMU_SET_CTX_REG(ctx, KGSL_IOMMU_CTX_ACTLR, val); > > > > > > > > > > > > > > Any idea how this works? And does it need to be done before or after > > > > > > > the ACTLR programming done in this patch? > > > > > > > > > > > > > > BR, > > > > > > > -R > > > > > > > > > > > > > > > > > > > Hi Rob, > > > > > > > > > > > > Can you please help provide some more clarification on the FIFO part? By FIFO are you referring to the storing of ACTLR data in the table? > > > > > > > > > > > > Thanks for pointing to the downstream implementation of kgsl driver for > > > > > > the PRR bit. Since kgsl driver is already handling this PRR bit's > > > > > > setting, this makes setting the PRR BIT(5) by SMMU driver redundant. > > > > > > > > > > The kgsl driver is not present upstream. > > > > > > > > > > > > > Right kgsl is not present upstream, it would be better to avoid configuring the PRR bit and can be handled by kgsl directly in downstream. > > > > > > No! Upstream is not a dumping ground to reduce your technical debt. > > > > > > There is no kgsl driver upstream, so this ought to be handled here, in > > > the iommu driver (as poking at hardware A from driver B is usually not good > > > practice). > > > > I'd second the request here. If another driver has to control the > > behaviour of another driver, please add corresponding API for that. > > We have adreno_smmu_priv for this purpose ;-) Exactly > > BR, > -R > > > > > > > > > > > > > > Thanks for bringing up this point. > > > > > > I will send v10 patch series removing this BIT(5) setting from the ACTLR > > > > > > table. > > > > > > > > > > I think it's generally saner to configure the SMMU from the SMMU driver.. > > > > > > > > Yes, agree on this. But since PRR bit is not directly related to SMMU > > > > configuration so I think it would be better to remove this PRR bit > > > > setting from SMMU driver based on my understanding. > > > > > > Why is it not related? We still don't know what it does. > > > > > > Konrad > > > > -- > > With best wishes > > Dmitry -- With best wishes Dmitry