Re: [PATCH v10 15/15] arm64: dts: qcom: sa8775p: add a dedicated memory carveout for TZ

[Konrad Dybcio]

On 29.05.2024 4:39 PM, Bartosz Golaszewski wrote:
> On Wed, May 29, 2024 at 4:26 PM Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> wrote:
>>
>> On 27.05.2024 2:55 PM, Bartosz Golaszewski wrote:
>>> From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
>>>
>>> Add a 20MB reserved memory region for use by SCM calls.
>>>
>>> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
>>> ---
>>>  arch/arm64/boot/dts/qcom/sa8775p.dtsi | 7 +++++++
>>>  1 file changed, 7 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/qcom/sa8775p.dtsi b/arch/arm64/boot/dts/qcom/sa8775p.dtsi
>>> index 31de73594839..c183527452d7 100644
>>> --- a/arch/arm64/boot/dts/qcom/sa8775p.dtsi
>>> +++ b/arch/arm64/boot/dts/qcom/sa8775p.dtsi
>>> @@ -208,6 +208,7 @@ core3 {
>>>       firmware {
>>>               scm {
>>>                       compatible = "qcom,scm-sa8775p", "qcom,scm";
>>> +                     memory-region = <&tz_ffi_mem>;
>>>               };
>>>       };
>>>
>>> @@ -418,6 +419,12 @@ cdt_data_backup_mem: cdt-data-backup@91ba0000 {
>>>                       no-map;
>>>               };
>>>
>>> +             tz_ffi_mem: tz-ffi@91c00000 {
>>> +                     compatible = "shared-dma-pool";
>>> +                     reg = <0x0 0x91c00000 0x0 0x1400000>;
>>
>> How does that size relate to
>>
>> +       pool_config.max_size = SZ_256K;
>>
>> in patch 3?
>>
>> Konrad
> 
> Short answer: it doesn't.
> 
> Slightly less short answer: this is the limit of *this* specific TZMem
> pool which in turn gets its memory from the shared DMA pool. We can
> have multiple TZMem pools and they all share this DMA pool.

OK makes sense, thanks

Konrad