| Message ID | 20210326231303.3071950-1-eric@anholt.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] iommu/arm-smmu-qcom: Skip the TTBR1 quirk for db820c. | expand |
On Fri, Mar 26, 2021 at 04:13:02PM -0700, Eric Anholt wrote: > db820c wants to use the qcom smmu path to get HUPCF set (which keeps > the GPU from wedging and then sometimes wedging the kernel after a > page fault), but it doesn't have separate pagetables support yet in > drm/msm so we can't go all the way to the TTBR1 path. What do you mean by "doesn't have separate pagetables support yet"? The compatible string doesn't feel like the right way to determine this. Will
On Mon, Mar 29, 2021 at 7:47 AM Will Deacon <will@kernel.org> wrote: > > On Fri, Mar 26, 2021 at 04:13:02PM -0700, Eric Anholt wrote: > > db820c wants to use the qcom smmu path to get HUPCF set (which keeps > > the GPU from wedging and then sometimes wedging the kernel after a > > page fault), but it doesn't have separate pagetables support yet in > > drm/msm so we can't go all the way to the TTBR1 path. > > What do you mean by "doesn't have separate pagetables support yet"? The > compatible string doesn't feel like the right way to determine this. In my past experience with DT, software looking at the (existing) board-specific compatibles has been a typical mechanism used to resolve something like this "ok, but you need to actually get down to what board is involved here to figure out how to play along with the rest of Linux that later attaches to other DT nodes". Do you have a preferred mechanism here?
On Fri 26 Mar 18:13 CDT 2021, Eric Anholt wrote: > db820c wants to use the qcom smmu path to get HUPCF set (which keeps > the GPU from wedging and then sometimes wedging the kernel after a > page fault), but it doesn't have separate pagetables support yet in > drm/msm so we can't go all the way to the TTBR1 path. > > Signed-off-by: Eric Anholt <eric@anholt.net> Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Regards, Bjorn > --- > > We've been seeing a flaky test per day or so in Mesa CI where the > kernel gets wedged after an iommu fault turns into CP errors. With > this patch, the CI isn't throwing the string of CP errors on the > faults in any of the ~10 jobs I've run so far. > > drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 13 ++++++++++++- > 1 file changed, 12 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 bcda17012aee..51f22193e456 100644 > --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c > @@ -130,6 +130,16 @@ static int qcom_adreno_smmu_alloc_context_bank(struct arm_smmu_domain *smmu_doma > return __arm_smmu_alloc_bitmap(smmu->context_map, start, count); > } > > +static bool qcom_adreno_can_do_ttbr1(struct arm_smmu_device *smmu) > +{ > + const struct device_node *np = smmu->dev->of_node; > + > + if (of_device_is_compatible(np, "qcom,msm8996-smmu-v2")) > + return false; > + > + return true; > +} > + > static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain, > struct io_pgtable_cfg *pgtbl_cfg, struct device *dev) > { > @@ -144,7 +154,8 @@ static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain, > * be AARCH64 stage 1 but double check because the arm-smmu code assumes > * that is the case when the TTBR1 quirk is enabled > */ > - if ((smmu_domain->stage == ARM_SMMU_DOMAIN_S1) && > + if (qcom_adreno_can_do_ttbr1(smmu_domain->smmu) && > + (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) && > (smmu_domain->cfg.fmt == ARM_SMMU_CTX_FMT_AARCH64)) > pgtbl_cfg->quirks |= IO_PGTABLE_QUIRK_ARM_TTBR1; > > -- > 2.31.0 >
On Mon, Mar 29, 2021 at 7:47 AM Will Deacon <will@kernel.org> wrote: > > On Fri, Mar 26, 2021 at 04:13:02PM -0700, Eric Anholt wrote: > > db820c wants to use the qcom smmu path to get HUPCF set (which keeps > > the GPU from wedging and then sometimes wedging the kernel after a > > page fault), but it doesn't have separate pagetables support yet in > > drm/msm so we can't go all the way to the TTBR1 path. > > What do you mean by "doesn't have separate pagetables support yet"? The > compatible string doesn't feel like the right way to determine this. the compatible string identifies what it is, not what the sw limitations are, so in that regard it seems right to me.. BR, -R
On Mon, Mar 29, 2021 at 09:02:50PM -0700, Rob Clark wrote: > On Mon, Mar 29, 2021 at 7:47 AM Will Deacon <will@kernel.org> wrote: > > > > On Fri, Mar 26, 2021 at 04:13:02PM -0700, Eric Anholt wrote: > > > db820c wants to use the qcom smmu path to get HUPCF set (which keeps > > > the GPU from wedging and then sometimes wedging the kernel after a > > > page fault), but it doesn't have separate pagetables support yet in > > > drm/msm so we can't go all the way to the TTBR1 path. > > > > What do you mean by "doesn't have separate pagetables support yet"? The > > compatible string doesn't feel like the right way to determine this. > > the compatible string identifies what it is, not what the sw > limitations are, so in that regard it seems right to me.. Well it depends on what "doesn't have separate pagetables support yet" means. I can't tell if it's a hardware issue, a firmware issue or a driver issue. Will
On Tue, Mar 30, 2021 at 2:34 AM Will Deacon <will@kernel.org> wrote: > > On Mon, Mar 29, 2021 at 09:02:50PM -0700, Rob Clark wrote: > > On Mon, Mar 29, 2021 at 7:47 AM Will Deacon <will@kernel.org> wrote: > > > > > > On Fri, Mar 26, 2021 at 04:13:02PM -0700, Eric Anholt wrote: > > > > db820c wants to use the qcom smmu path to get HUPCF set (which keeps > > > > the GPU from wedging and then sometimes wedging the kernel after a > > > > page fault), but it doesn't have separate pagetables support yet in > > > > drm/msm so we can't go all the way to the TTBR1 path. > > > > > > What do you mean by "doesn't have separate pagetables support yet"? The > > > compatible string doesn't feel like the right way to determine this. > > > > the compatible string identifies what it is, not what the sw > > limitations are, so in that regard it seems right to me.. > > Well it depends on what "doesn't have separate pagetables support yet" > means. I can't tell if it's a hardware issue, a firmware issue or a driver > issue. Just a driver issue (and the fact that currently we don't have physical access to a device... debugging a5xx per-process-pgtables by pushing untested things to the CI farm is kind of a difficult way to work) BR, -R
On Tue, Mar 30, 2021 at 08:03:36AM -0700, Rob Clark wrote: > On Tue, Mar 30, 2021 at 2:34 AM Will Deacon <will@kernel.org> wrote: > > > > On Mon, Mar 29, 2021 at 09:02:50PM -0700, Rob Clark wrote: > > > On Mon, Mar 29, 2021 at 7:47 AM Will Deacon <will@kernel.org> wrote: > > > > > > > > On Fri, Mar 26, 2021 at 04:13:02PM -0700, Eric Anholt wrote: > > > > > db820c wants to use the qcom smmu path to get HUPCF set (which keeps > > > > > the GPU from wedging and then sometimes wedging the kernel after a > > > > > page fault), but it doesn't have separate pagetables support yet in > > > > > drm/msm so we can't go all the way to the TTBR1 path. > > > > > > > > What do you mean by "doesn't have separate pagetables support yet"? The > > > > compatible string doesn't feel like the right way to determine this. > > > > > > the compatible string identifies what it is, not what the sw > > > limitations are, so in that regard it seems right to me.. > > > > Well it depends on what "doesn't have separate pagetables support yet" > > means. I can't tell if it's a hardware issue, a firmware issue or a driver > > issue. > > Just a driver issue (and the fact that currently we don't have > physical access to a device... debugging a5xx per-process-pgtables by > pushing untested things to the CI farm is kind of a difficult way to > work) But then in that case, this is using the compatible string to identify a driver issue, no? Will
On Tue, Mar 30, 2021 at 8:31 AM Will Deacon <will@kernel.org> wrote: > > On Tue, Mar 30, 2021 at 08:03:36AM -0700, Rob Clark wrote: > > On Tue, Mar 30, 2021 at 2:34 AM Will Deacon <will@kernel.org> wrote: > > > > > > On Mon, Mar 29, 2021 at 09:02:50PM -0700, Rob Clark wrote: > > > > On Mon, Mar 29, 2021 at 7:47 AM Will Deacon <will@kernel.org> wrote: > > > > > > > > > > On Fri, Mar 26, 2021 at 04:13:02PM -0700, Eric Anholt wrote: > > > > > > db820c wants to use the qcom smmu path to get HUPCF set (which keeps > > > > > > the GPU from wedging and then sometimes wedging the kernel after a > > > > > > page fault), but it doesn't have separate pagetables support yet in > > > > > > drm/msm so we can't go all the way to the TTBR1 path. > > > > > > > > > > What do you mean by "doesn't have separate pagetables support yet"? The > > > > > compatible string doesn't feel like the right way to determine this. > > > > > > > > the compatible string identifies what it is, not what the sw > > > > limitations are, so in that regard it seems right to me.. > > > > > > Well it depends on what "doesn't have separate pagetables support yet" > > > means. I can't tell if it's a hardware issue, a firmware issue or a driver > > > issue. > > > > Just a driver issue (and the fact that currently we don't have > > physical access to a device... debugging a5xx per-process-pgtables by > > pushing untested things to the CI farm is kind of a difficult way to > > work) > > But then in that case, this is using the compatible string to identify a > driver issue, no? > Well, I suppose yes.. but OTOH it is keeping the problem out of the dtb. Once per-process pgtables works for a5xx, there would be no dtb change, just a change to the quirk behavior in arm-smmu-qcom. BR, -R
On Tue 30 Mar 10:31 CDT 2021, Will Deacon wrote: > On Tue, Mar 30, 2021 at 08:03:36AM -0700, Rob Clark wrote: > > On Tue, Mar 30, 2021 at 2:34 AM Will Deacon <will@kernel.org> wrote: > > > > > > On Mon, Mar 29, 2021 at 09:02:50PM -0700, Rob Clark wrote: > > > > On Mon, Mar 29, 2021 at 7:47 AM Will Deacon <will@kernel.org> wrote: > > > > > > > > > > On Fri, Mar 26, 2021 at 04:13:02PM -0700, Eric Anholt wrote: > > > > > > db820c wants to use the qcom smmu path to get HUPCF set (which keeps > > > > > > the GPU from wedging and then sometimes wedging the kernel after a > > > > > > page fault), but it doesn't have separate pagetables support yet in > > > > > > drm/msm so we can't go all the way to the TTBR1 path. > > > > > > > > > > What do you mean by "doesn't have separate pagetables support yet"? The > > > > > compatible string doesn't feel like the right way to determine this. > > > > > > > > the compatible string identifies what it is, not what the sw > > > > limitations are, so in that regard it seems right to me.. > > > > > > Well it depends on what "doesn't have separate pagetables support yet" > > > means. I can't tell if it's a hardware issue, a firmware issue or a driver > > > issue. > > > > Just a driver issue (and the fact that currently we don't have > > physical access to a device... debugging a5xx per-process-pgtables by > > pushing untested things to the CI farm is kind of a difficult way to > > work) > > But then in that case, this is using the compatible string to identify a > driver issue, no? > No the compatible addition identifies the hardware, the implementation then uses this information to know that it needs to behave "differently" on this platform. When/if someone decides to add the necessary support in the driver they can remove the driver quirk, but it doesn't invalidate the specific compatible. Regards, Bjorn
On Fri, 26 Mar 2021 16:13:02 -0700, Eric Anholt wrote: > db820c wants to use the qcom smmu path to get HUPCF set (which keeps > the GPU from wedging and then sometimes wedging the kernel after a > page fault), but it doesn't have separate pagetables support yet in > drm/msm so we can't go all the way to the TTBR1 path. Applied to will (for-joerg/arm-smmu/updates), thanks! [1/2] iommu/arm-smmu-qcom: Skip the TTBR1 quirk for db820c. https://git.kernel.org/will/c/a242f4297cfe [2/2] arm64: dts: msm8996: Mark the GPU's SMMU as an adreno one. https://git.kernel.org/will/c/19c07b91f85d Cheers,
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c index bcda17012aee..51f22193e456 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c @@ -130,6 +130,16 @@ static int qcom_adreno_smmu_alloc_context_bank(struct arm_smmu_domain *smmu_doma return __arm_smmu_alloc_bitmap(smmu->context_map, start, count); } +static bool qcom_adreno_can_do_ttbr1(struct arm_smmu_device *smmu) +{ + const struct device_node *np = smmu->dev->of_node; + + if (of_device_is_compatible(np, "qcom,msm8996-smmu-v2")) + return false; + + return true; +} + static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain, struct io_pgtable_cfg *pgtbl_cfg, struct device *dev) { @@ -144,7 +154,8 @@ static int qcom_adreno_smmu_init_context(struct arm_smmu_domain *smmu_domain, * be AARCH64 stage 1 but double check because the arm-smmu code assumes * that is the case when the TTBR1 quirk is enabled */ - if ((smmu_domain->stage == ARM_SMMU_DOMAIN_S1) && + if (qcom_adreno_can_do_ttbr1(smmu_domain->smmu) && + (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) && (smmu_domain->cfg.fmt == ARM_SMMU_CTX_FMT_AARCH64)) pgtbl_cfg->quirks |= IO_PGTABLE_QUIRK_ARM_TTBR1;
db820c wants to use the qcom smmu path to get HUPCF set (which keeps the GPU from wedging and then sometimes wedging the kernel after a page fault), but it doesn't have separate pagetables support yet in drm/msm so we can't go all the way to the TTBR1 path. Signed-off-by: Eric Anholt <eric@anholt.net> --- We've been seeing a flaky test per day or so in Mesa CI where the kernel gets wedged after an iommu fault turns into CP errors. With this patch, the CI isn't throwing the string of CP errors on the faults in any of the ~10 jobs I've run so far. drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)