[PATCH] iommu/arm-smmu-qcom: create qcom_smmu_impl for ACPI boot

[Shawn Guo]

On Thu, Mar 25, 2021 at 12:02:56PM -0500, Bjorn Andersson wrote:
> On Thu 25 Mar 09:59 CDT 2021, Will Deacon wrote:
> 
> > [+ Lorenzo]
> > 
> > On Mon, Mar 01, 2021 at 03:40:21PM +0800, Shawn Guo wrote:
> > > Though qcom_adreno_smmu_impl is not used by ACPI boot right now,
> > > qcom_smmu_impl is already required at least to boot up Lenovo Flex 5G
> > > laptop.  Let's check asl_compiler_id in IORT header to ensure we are
> > > running a QCOM SMMU and create qcom_smmu_impl for it.
> > > 
> > > !np is used to check ACPI boot, because fwnode of SMMU device is
> > > a static allocation and thus has_acpi_companion() doesn't work here.
> > > 
> > > Signed-off-by: Shawn Guo <shawn.guo at linaro.org>
> > > ---
> > >  drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 33 ++++++++++++++++++++++
> > >  1 file changed, 33 insertions(+)
> > 
> > I don't know what a "asl_compiler_id" is, but it doesn't sound like it
> > has an awful lot to do with the SMMU.
> > 
> 
> I would prefer that we somehow relate this to the particular board,
> rather than all Qualcomm-related ACPI tables. E.g. by relying on the
> SMMU devices having a _HID of QCOM0409.
> 
> Shawn, any reason for this wouldn't be possible?

The arm-smmu driver is probing a device created from IORT table rather
DSDT, and there is no info like HID that can be found around the device.

Shawn