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

[Robin Murphy]

On 2021-03-25 17:02, 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?

To do something broadly similar to identify HiSilicon's SMMU PMCG 
implementation, we use acpi_match_platform_list() - could we do the same 
for this?

Robin.

>> Lorenzo -- any idea what we should be doing here instead? Probably not
>> using ACPI?
>>
> 
> The 8cx (aka sc8180x) platform comes with Qualcomm's usual SMMU
> stream-mapping quirks and this is one of the patches needed to bring
> enough ACPI support to run the Debian installer that Shawn has been
> working on. After the installer we currently only boot this using DT -
> which already enables the quirk.
> 
> Regards,
> Bjorn
>