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[v1,1/7] dt-bindings: i2c: qcom,i2c-geni: Document DT properties for QUP firmware loading

Message ID 20241204150326.1470749-2-quic_vdadhani@quicinc.com
State New
Headers show
Series [v1,1/7] dt-bindings: i2c: qcom,i2c-geni: Document DT properties for QUP firmware loading | expand

Commit Message

Viken Dadhaniya Dec. 4, 2024, 3:03 p.m. UTC 
Document the 'qcom,load-firmware' and 'qcom,xfer-mode' properties to
support SE(Serial Engine) firmware loading from the protocol driver and to
select the data transfer mode, either GPI DMA (Generic Packet Interface)
or non-GPI mode (PIO/CPU DMA).

I2C controller can operate in one of two modes based on the
'qcom,xfer-mode' property, and the firmware is loaded accordingly.

Co-developed-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
Signed-off-by: Viken Dadhaniya <quic_vdadhani@quicinc.com>
---
 .../devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml   | 11 +++++++++++
 1 file changed, 11 insertions(+)

Comments

Viken Dadhaniya Dec. 10, 2024, 4:43 a.m. UTC | #1 
Thanks Krzysztof for the review and helpful comments.

On 12/4/2024 8:36 PM, Krzysztof Kozlowski wrote:
> On 04/12/2024 16:03, Viken Dadhaniya wrote:
>> Document the 'qcom,load-firmware' and 'qcom,xfer-mode' properties to
>> support SE(Serial Engine) firmware loading from the protocol driver and to
>> select the data transfer mode, either GPI DMA (Generic Packet Interface)
>> or non-GPI mode (PIO/CPU DMA).
> 
> 
> You described the desired Linux feature or behavior, not the actual
> hardware. The bindings are about the latter, so instead you need to
> rephrase the property and its description to match actual hardware
> capabilities/features/configuration etc.
Sure, IIUC, i should explain the need of FW loading. Agree that binding 
is for the hardware. This feature needs to have some intelligence to 
know that Software driver needs to load Firmware or not ?

Let me add description about the actual hardware capabilities, its 
features. Hope this can be better from my side on V2.
> 
> I don't quite get why firmware-name is not suitable here, what is
> "protocol driver" in this context and how firmware is loaded from it?
> 
yes, as per Dmitry's comment, i should replace with 
/soc/sc7180/firmware.  This would be become "firmware-name" property 
instead of qcom,load-firmware.

>>
>> I2C controller can operate in one of two modes based on the
>> 'qcom,xfer-mode' property, and the firmware is loaded accordingly.
>>
>> Co-developed-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
>> Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
>> Signed-off-by: Viken Dadhaniya <quic_vdadhani@quicinc.com>
>> ---
>>   .../devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml   | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>> index 9f66a3bb1f80..a26f34fce1bb 100644
>> --- a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>> +++ b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>> @@ -66,6 +66,15 @@ properties:
>>     required-opps:
>>       maxItems: 1
>>   
>> +  qcom,load-firmware:
>> +    type: boolean
>> +    description: Optional property to load SE (serial engine) Firmware from protocol driver.
> 
> 
> Please wrap code according to coding style (checkpatch is not a coding
> style description, but only a tool).
Actually i have ran dt-schema for yaml validation. I couldn't get if you 
have any comment for description statement OR it's related to code ? 
Could you please be more descriptive so i can adopt the suggestions.
> 
> 
>> +
>> +  qcom,xfer-mode:
>> +    description: Value 1,2 and 3 represents FIFO, CPU DMA and GSI DMA mode respectively.
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    enum: [1, 2, 3]
> 
> 
> Use string but anyway this would need some changes and explanation why
> lack of DMA cannot be used to determine that. CPU DMA and GSI DMA also
> need some background.
Sure, i got it.
I need to add enum strings and shall provide explanation abut modes in use.
As per Doug's comment, we plan to keep GSI and non-GSI mode. It would be 
more clear in next patch.
> 
> 
> 
> Best regards,
> Krzysztof
Viken Dadhaniya Dec. 10, 2024, 4:44 a.m. UTC | #2 
On 12/4/2024 8:55 PM, neil.armstrong@linaro.org wrote:
> On 04/12/2024 16:03, Viken Dadhaniya wrote:
>> Document the 'qcom,load-firmware' and 'qcom,xfer-mode' properties to
>> support SE(Serial Engine) firmware loading from the protocol driver 
>> and to
>> select the data transfer mode, either GPI DMA (Generic Packet Interface)
>> or non-GPI mode (PIO/CPU DMA).
>>
>> I2C controller can operate in one of two modes based on the
>> 'qcom,xfer-mode' property, and the firmware is loaded accordingly.
>>
>> Co-developed-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
>> Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
>> Signed-off-by: Viken Dadhaniya <quic_vdadhani@quicinc.com>
>> ---
>>   .../devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml   | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git 
>> a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml 
>> b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>> index 9f66a3bb1f80..a26f34fce1bb 100644
>> --- a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>> +++ b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>> @@ -66,6 +66,15 @@ properties:
>>     required-opps:
>>       maxItems: 1
>> +  qcom,load-firmware:
>> +    type: boolean
>> +    description: Optional property to load SE (serial engine) 
>> Firmware from protocol driver.
>> +
>> +  qcom,xfer-mode:
>> +    description: Value 1,2 and 3 represents FIFO, CPU DMA and GSI DMA 
>> mode respectively.
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    enum: [1, 2, 3]
> 
> In the code, FIFO mode is default if not specified, please precise it in 
> the
> bindings aswell.
> 
> Thanks,
> Neil

Sure will update in next patch.

> 
>> +
>>   required:
>>     - compatible
>>     - interrupts
>> @@ -142,5 +151,7 @@ examples:
>>           interconnect-names = "qup-core", "qup-config", "qup-memory";
>>           power-domains = <&rpmhpd SC7180_CX>;
>>           required-opps = <&rpmhpd_opp_low_svs>;
>> +        qcom,load-firmware;
>> +        qcom,xfer-mode = <1>;
>>       };
>>   ...
>
Viken Dadhaniya Dec. 10, 2024, 4:48 a.m. UTC | #3 
On 12/5/2024 4:06 AM, Dmitry Baryshkov wrote:
> On Wed, Dec 04, 2024 at 08:33:20PM +0530, Viken Dadhaniya wrote:
>> Document the 'qcom,load-firmware' and 'qcom,xfer-mode' properties to
>> support SE(Serial Engine) firmware loading from the protocol driver and to
>> select the data transfer mode, either GPI DMA (Generic Packet Interface)
>> or non-GPI mode (PIO/CPU DMA).
>>
>> I2C controller can operate in one of two modes based on the
>> 'qcom,xfer-mode' property, and the firmware is loaded accordingly.
>>
>> Co-developed-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
>> Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
>> Signed-off-by: Viken Dadhaniya <quic_vdadhani@quicinc.com>
>> ---
>>   .../devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml   | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>> index 9f66a3bb1f80..a26f34fce1bb 100644
>> --- a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>> +++ b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>> @@ -66,6 +66,15 @@ properties:
>>     required-opps:
>>       maxItems: 1
>>   
>> +  qcom,load-firmware:
>> +    type: boolean
>> +    description: Optional property to load SE (serial engine) Firmware from protocol driver.
>> +
>> +  qcom,xfer-mode:
>> +    description: Value 1,2 and 3 represents FIFO, CPU DMA and GSI DMA mode respectively.
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    enum: [1, 2, 3]
>> +
>>   required:
>>     - compatible
>>     - interrupts
>> @@ -142,5 +151,7 @@ examples:
>>           interconnect-names = "qup-core", "qup-config", "qup-memory";
>>           power-domains = <&rpmhpd SC7180_CX>;
>>           required-opps = <&rpmhpd_opp_low_svs>;
>> +        qcom,load-firmware;
> 
> please use instead:
> firmware-name = "qcom/sc7180/qupv3.elf"

Agreed, will be adopted in next patch.

> 
>> +        qcom,xfer-mode = <1>;
>>       };
>>   ...
>> -- 
>> 2.34.1
>>
>
Viken Dadhaniya Dec. 10, 2024, 5:28 a.m. UTC | #4 
On 12/4/2024 10:55 PM, Doug Anderson wrote:
> Hi,
> 
> On Wed, Dec 4, 2024 at 7:03 AM Viken Dadhaniya
> <quic_vdadhani@quicinc.com> wrote:
>>
>> Document the 'qcom,load-firmware' and 'qcom,xfer-mode' properties to
>> support SE(Serial Engine) firmware loading from the protocol driver and to
>> select the data transfer mode, either GPI DMA (Generic Packet Interface)
>> or non-GPI mode (PIO/CPU DMA).
>>
>> I2C controller can operate in one of two modes based on the
>> 'qcom,xfer-mode' property, and the firmware is loaded accordingly.
>>
>> Co-developed-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
>> Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
>> Signed-off-by: Viken Dadhaniya <quic_vdadhani@quicinc.com>
>> ---
>>   .../devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml   | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>> index 9f66a3bb1f80..a26f34fce1bb 100644
>> --- a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>> +++ b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>> @@ -66,6 +66,15 @@ properties:
>>     required-opps:
>>       maxItems: 1
>>
>> +  qcom,load-firmware:
>> +    type: boolean
>> +    description: Optional property to load SE (serial engine) Firmware from protocol driver.
>> +
>> +  qcom,xfer-mode:
>> +    description: Value 1,2 and 3 represents FIFO, CPU DMA and GSI DMA mode respectively.
>> +    $ref: /schemas/types.yaml#/definitions/uint32
>> +    enum: [1, 2, 3]
> 
> I'm a little confused about this. I'll admit I haven't fully analyzed
> your patch with actual code in it, but in the past "CPU DMA" mode and
> "FIFO" mode were compatible with each other and then it was up to the
> driver to decide which of the two modes made sense in any given
> situation. For instance, last I looked at the i2c driver it tried to
> use DMA for large transfers and FIFO for small transfers. The SPI
> driver also has some cases where it will use DMA mode and then
> fallback to FIFO mode.
> 
> ...so what exactly is the point of differentiating between "FIFO" and
> "CPU DMA" mode here?

Yes, correct, Will update in V2.
I plan to add 2 modes, GSI and non-GSI(PIO or DMA based on length).

> 
> Then when it comes to "GSI DMA" mode, my understanding is that the
> firmware for "GSI DMA" mode is always loaded by Trustzone because the
> whole point is that the GSI mode arbitrates between multiple clients.
> Presumably if the firmware already loaded the GSI firmware then the
> code would just detect that case. ...so there shouldn't need to be any
> reason to specify GSI mode here either, right?
> 
> -Doug

GSI firmware is loaded from TZ per QUP, but to use GSI mode,
we need to configure the SE to use GSI mode by writing into SE register 
QUPV3_SE_GENI_DMA_MODE_EN and SE_GSI_EVENT_EN. This register is
used to configure data transfer mode for Serial Engine.
Krzysztof Kozlowski Dec. 10, 2024, 7:23 a.m. UTC | #5 
On 10/12/2024 05:43, Viken Dadhaniya wrote:
>>>       maxItems: 1
>>>   
>>> +  qcom,load-firmware:
>>> +    type: boolean
>>> +    description: Optional property to load SE (serial engine) Firmware from protocol driver.
>>
>>
>> Please wrap code according to coding style (checkpatch is not a coding
>> style description, but only a tool).
> Actually i have ran dt-schema for yaml validation. I couldn't get if you 
> have any comment for description statement OR it's related to code ? 
> Could you please be more descriptive so i can adopt the suggestions.

This code is not conforming to coding style in terms of wrapping, what
dtschema has to do with it? Please read coding style.



Best regards,
Krzysztof
Doug Anderson Dec. 10, 2024, 5:42 p.m. UTC | #6 
Hi,

On Mon, Dec 9, 2024 at 9:28 PM Viken Dadhaniya
<quic_vdadhani@quicinc.com> wrote:
>
> On 12/4/2024 10:55 PM, Doug Anderson wrote:
> > Hi,
> >
> > On Wed, Dec 4, 2024 at 7:03 AM Viken Dadhaniya
> > <quic_vdadhani@quicinc.com> wrote:
> >>
> >> Document the 'qcom,load-firmware' and 'qcom,xfer-mode' properties to
> >> support SE(Serial Engine) firmware loading from the protocol driver and to
> >> select the data transfer mode, either GPI DMA (Generic Packet Interface)
> >> or non-GPI mode (PIO/CPU DMA).
> >>
> >> I2C controller can operate in one of two modes based on the
> >> 'qcom,xfer-mode' property, and the firmware is loaded accordingly.
> >>
> >> Co-developed-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
> >> Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
> >> Signed-off-by: Viken Dadhaniya <quic_vdadhani@quicinc.com>
> >> ---
> >>   .../devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml   | 11 +++++++++++
> >>   1 file changed, 11 insertions(+)
> >>
> >> diff --git a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
> >> index 9f66a3bb1f80..a26f34fce1bb 100644
> >> --- a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
> >> +++ b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
> >> @@ -66,6 +66,15 @@ properties:
> >>     required-opps:
> >>       maxItems: 1
> >>
> >> +  qcom,load-firmware:
> >> +    type: boolean
> >> +    description: Optional property to load SE (serial engine) Firmware from protocol driver.
> >> +
> >> +  qcom,xfer-mode:
> >> +    description: Value 1,2 and 3 represents FIFO, CPU DMA and GSI DMA mode respectively.
> >> +    $ref: /schemas/types.yaml#/definitions/uint32
> >> +    enum: [1, 2, 3]
> >
> > I'm a little confused about this. I'll admit I haven't fully analyzed
> > your patch with actual code in it, but in the past "CPU DMA" mode and
> > "FIFO" mode were compatible with each other and then it was up to the
> > driver to decide which of the two modes made sense in any given
> > situation. For instance, last I looked at the i2c driver it tried to
> > use DMA for large transfers and FIFO for small transfers. The SPI
> > driver also has some cases where it will use DMA mode and then
> > fallback to FIFO mode.
> >
> > ...so what exactly is the point of differentiating between "FIFO" and
> > "CPU DMA" mode here?
>
> Yes, correct, Will update in V2.
> I plan to add 2 modes, GSI and non-GSI(PIO or DMA based on length).
>
> >
> > Then when it comes to "GSI DMA" mode, my understanding is that the
> > firmware for "GSI DMA" mode is always loaded by Trustzone because the
> > whole point is that the GSI mode arbitrates between multiple clients.
> > Presumably if the firmware already loaded the GSI firmware then the
> > code would just detect that case. ...so there shouldn't need to be any
> > reason to specify GSI mode here either, right?
> >
> > -Doug
>
> GSI firmware is loaded from TZ per QUP, but to use GSI mode,
> we need to configure the SE to use GSI mode by writing into SE register
> QUPV3_SE_GENI_DMA_MODE_EN and SE_GSI_EVENT_EN. This register is
> used to configure data transfer mode for Serial Engine.

Can't you detect it's in GSI mode without any device tree property
like the code does today?

-Doug
Viken Dadhaniya Dec. 11, 2024, 5:27 a.m. UTC | #7 
On 12/10/2024 11:12 PM, Doug Anderson wrote:
> Hi,
> 
> On Mon, Dec 9, 2024 at 9:28 PM Viken Dadhaniya
> <quic_vdadhani@quicinc.com> wrote:
>>
>> On 12/4/2024 10:55 PM, Doug Anderson wrote:
>>> Hi,
>>>
>>> On Wed, Dec 4, 2024 at 7:03 AM Viken Dadhaniya
>>> <quic_vdadhani@quicinc.com> wrote:
>>>>
>>>> Document the 'qcom,load-firmware' and 'qcom,xfer-mode' properties to
>>>> support SE(Serial Engine) firmware loading from the protocol driver and to
>>>> select the data transfer mode, either GPI DMA (Generic Packet Interface)
>>>> or non-GPI mode (PIO/CPU DMA).
>>>>
>>>> I2C controller can operate in one of two modes based on the
>>>> 'qcom,xfer-mode' property, and the firmware is loaded accordingly.
>>>>
>>>> Co-developed-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
>>>> Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
>>>> Signed-off-by: Viken Dadhaniya <quic_vdadhani@quicinc.com>
>>>> ---
>>>>    .../devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml   | 11 +++++++++++
>>>>    1 file changed, 11 insertions(+)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>>>> index 9f66a3bb1f80..a26f34fce1bb 100644
>>>> --- a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>>>> +++ b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
>>>> @@ -66,6 +66,15 @@ properties:
>>>>      required-opps:
>>>>        maxItems: 1
>>>>
>>>> +  qcom,load-firmware:
>>>> +    type: boolean
>>>> +    description: Optional property to load SE (serial engine) Firmware from protocol driver.
>>>> +
>>>> +  qcom,xfer-mode:
>>>> +    description: Value 1,2 and 3 represents FIFO, CPU DMA and GSI DMA mode respectively.
>>>> +    $ref: /schemas/types.yaml#/definitions/uint32
>>>> +    enum: [1, 2, 3]
>>>
>>> I'm a little confused about this. I'll admit I haven't fully analyzed
>>> your patch with actual code in it, but in the past "CPU DMA" mode and
>>> "FIFO" mode were compatible with each other and then it was up to the
>>> driver to decide which of the two modes made sense in any given
>>> situation. For instance, last I looked at the i2c driver it tried to
>>> use DMA for large transfers and FIFO for small transfers. The SPI
>>> driver also has some cases where it will use DMA mode and then
>>> fallback to FIFO mode.
>>>
>>> ...so what exactly is the point of differentiating between "FIFO" and
>>> "CPU DMA" mode here?
>>
>> Yes, correct, Will update in V2.
>> I plan to add 2 modes, GSI and non-GSI(PIO or DMA based on length).
>>
>>>
>>> Then when it comes to "GSI DMA" mode, my understanding is that the
>>> firmware for "GSI DMA" mode is always loaded by Trustzone because the
>>> whole point is that the GSI mode arbitrates between multiple clients.
>>> Presumably if the firmware already loaded the GSI firmware then the
>>> code would just detect that case. ...so there shouldn't need to be any
>>> reason to specify GSI mode here either, right?
>>>
>>> -Doug
>>
>> GSI firmware is loaded from TZ per QUP, but to use GSI mode,
>> we need to configure the SE to use GSI mode by writing into SE register
>> QUPV3_SE_GENI_DMA_MODE_EN and SE_GSI_EVENT_EN. This register is
>> used to configure data transfer mode for Serial Engine.
> 
> Can't you detect it's in GSI mode without any device tree property
> like the code does today?
> 
> -Doug

No, we can't detect GSI mode in the current design. The GSI firmware is 
loaded from the TZ side, while mode selection occurs on the APPS side 
based on the Device Tree property.
Doug Anderson Dec. 11, 2024, 10:27 p.m. UTC | #8 
Hi,

On Tue, Dec 10, 2024 at 9:27 PM Viken Dadhaniya
<quic_vdadhani@quicinc.com> wrote:
>
> On 12/10/2024 11:12 PM, Doug Anderson wrote:
> > Hi,
> >
> > On Mon, Dec 9, 2024 at 9:28 PM Viken Dadhaniya
> > <quic_vdadhani@quicinc.com> wrote:
> >>
> >> On 12/4/2024 10:55 PM, Doug Anderson wrote:
> >>> Hi,
> >>>
> >>> On Wed, Dec 4, 2024 at 7:03 AM Viken Dadhaniya
> >>> <quic_vdadhani@quicinc.com> wrote:
> >>>>
> >>>> Document the 'qcom,load-firmware' and 'qcom,xfer-mode' properties to
> >>>> support SE(Serial Engine) firmware loading from the protocol driver and to
> >>>> select the data transfer mode, either GPI DMA (Generic Packet Interface)
> >>>> or non-GPI mode (PIO/CPU DMA).
> >>>>
> >>>> I2C controller can operate in one of two modes based on the
> >>>> 'qcom,xfer-mode' property, and the firmware is loaded accordingly.
> >>>>
> >>>> Co-developed-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
> >>>> Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
> >>>> Signed-off-by: Viken Dadhaniya <quic_vdadhani@quicinc.com>
> >>>> ---
> >>>>    .../devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml   | 11 +++++++++++
> >>>>    1 file changed, 11 insertions(+)
> >>>>
> >>>> diff --git a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
> >>>> index 9f66a3bb1f80..a26f34fce1bb 100644
> >>>> --- a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
> >>>> +++ b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
> >>>> @@ -66,6 +66,15 @@ properties:
> >>>>      required-opps:
> >>>>        maxItems: 1
> >>>>
> >>>> +  qcom,load-firmware:
> >>>> +    type: boolean
> >>>> +    description: Optional property to load SE (serial engine) Firmware from protocol driver.
> >>>> +
> >>>> +  qcom,xfer-mode:
> >>>> +    description: Value 1,2 and 3 represents FIFO, CPU DMA and GSI DMA mode respectively.
> >>>> +    $ref: /schemas/types.yaml#/definitions/uint32
> >>>> +    enum: [1, 2, 3]
> >>>
> >>> I'm a little confused about this. I'll admit I haven't fully analyzed
> >>> your patch with actual code in it, but in the past "CPU DMA" mode and
> >>> "FIFO" mode were compatible with each other and then it was up to the
> >>> driver to decide which of the two modes made sense in any given
> >>> situation. For instance, last I looked at the i2c driver it tried to
> >>> use DMA for large transfers and FIFO for small transfers. The SPI
> >>> driver also has some cases where it will use DMA mode and then
> >>> fallback to FIFO mode.
> >>>
> >>> ...so what exactly is the point of differentiating between "FIFO" and
> >>> "CPU DMA" mode here?
> >>
> >> Yes, correct, Will update in V2.
> >> I plan to add 2 modes, GSI and non-GSI(PIO or DMA based on length).
> >>
> >>>
> >>> Then when it comes to "GSI DMA" mode, my understanding is that the
> >>> firmware for "GSI DMA" mode is always loaded by Trustzone because the
> >>> whole point is that the GSI mode arbitrates between multiple clients.
> >>> Presumably if the firmware already loaded the GSI firmware then the
> >>> code would just detect that case. ...so there shouldn't need to be any
> >>> reason to specify GSI mode here either, right?
> >>>
> >>> -Doug
> >>
> >> GSI firmware is loaded from TZ per QUP, but to use GSI mode,
> >> we need to configure the SE to use GSI mode by writing into SE register
> >> QUPV3_SE_GENI_DMA_MODE_EN and SE_GSI_EVENT_EN. This register is
> >> used to configure data transfer mode for Serial Engine.
> >
> > Can't you detect it's in GSI mode without any device tree property
> > like the code does today?
> >
> > -Doug
>
> No, we can't detect GSI mode in the current design. The GSI firmware is
> loaded from the TZ side, while mode selection occurs on the APPS side
> based on the Device Tree property.

Presumably you can check to see if the geni firmware has already been
loaded before the kernel started, right? In the case that it's already
loaded, can't you fall back to the way that existing code detects GSI
mode? From reading `drivers/spi/spi-geni-qcom.c` I see that if the
FIFO is disabled then it assumes we must be in GSI mode...
Specifically, it checks:

readl(se->base + GENI_IF_DISABLE_RO) & FIFO_IF_DISABLE;

The i2c code today (`drivers/i2c/busses/i2c-qcom-geni.c`) does the same.

So, essentially:

* If geni firmware has already been loaded, then check
FIFO_IF_DISABLE. If the FIFO is disabled it's GSI. If not then both
"CPU DMA" and "FIFO" are allowed.

* If geni firmware hasn't already been loaded then it's impossible to
be in GSI mode since GSI only makes sense if the geni firmware was
loaded before the kernel started. Thus we're in "CPU DMA" / "FIFO"
mode.

In both cases you don't need an attribute telling you whether to use
GSI mode or not, right?

-Doug
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
index 9f66a3bb1f80..a26f34fce1bb 100644
--- a/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
+++ b/Documentation/devicetree/bindings/i2c/qcom,i2c-geni-qcom.yaml
@@ -66,6 +66,15 @@  properties:
   required-opps:
     maxItems: 1
 
+  qcom,load-firmware:
+    type: boolean
+    description: Optional property to load SE (serial engine) Firmware from protocol driver.
+
+  qcom,xfer-mode:
+    description: Value 1,2 and 3 represents FIFO, CPU DMA and GSI DMA mode respectively.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [1, 2, 3]
+
 required:
   - compatible
   - interrupts
@@ -142,5 +151,7 @@  examples:
         interconnect-names = "qup-core", "qup-config", "qup-memory";
         power-domains = <&rpmhpd SC7180_CX>;
         required-opps = <&rpmhpd_opp_low_svs>;
+        qcom,load-firmware;
+        qcom,xfer-mode = <1>;
     };
 ...