24.01.2019 21:29, navneet kumar пишет:
> On 1/17/19 7:25 AM, Dmitry Osipenko wrote:
>> 16.01.2019 23:50, Navneet Kumar пишет:
>>> Use PTB_ASID instead of SMMU_CONFIG to flush smmu.
>>> PTB_ASID can be accessed from non-secure mode, SMMU_CONFIG cannot be.
>>> Using SMMU_CONFIG could pose a problem when kernel doesn't have secure
>>> mode access enabled from boot.
>>>
>>> Signed-off-by: Navneet Kumar <navneetk@xxxxxxxxxx>
>>> ---
>>> drivers/iommu/tegra-smmu.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
>>> index ee4d8a8..fa175d9 100644
>>> --- a/drivers/iommu/tegra-smmu.c
>>> +++ b/drivers/iommu/tegra-smmu.c
>>> @@ -235,7 +235,7 @@ static inline void smmu_flush_tlb_group(struct tegra_smmu *smmu,
>>>
>>> static inline void smmu_flush(struct tegra_smmu *smmu)
>>> {
>>> - smmu_readl(smmu, SMMU_CONFIG);
>>> + smmu_readl(smmu, SMMU_PTB_ASID);
>>> }
>>>
>>> static int tegra_smmu_alloc_asid(struct tegra_smmu *smmu, unsigned int *idp)
>>>
>>
>> Driver writes to SMMU_CONFIG during of the probing. Looks like it's better to drop this patch for now and make it part of a complete solution that will add proper support for a stricter insecure-mode platforms.
>>
> Thanks for the comment Dmitry. On secure platforms, writing to SMMU_CONFIG will be a no-op and
> will pose no harm. Having this patch is important because it fixes the flushing behavior on
> such platforms, which is critical.
>
> I propose to keep this patch as is, however, i can add more explanation to the commit message,
> stating the case of probe and how it will not have any ill effects. Pls ACK/NACK, and i shall post
> a V2.
>
Nothing breaks with this change at least for T30. Please extend the commit message and add a clarifying comment to the code, thanks.
With the clarifying message being addressed:
Reviewed-by: Dmitry Osipenko <digetx@xxxxxxxxx>
Tested-by: Dmitry Osipenko <digetx@xxxxxxxxx>
