On 16/08/2023 10:51, Naresh Solanki wrote: > Hi Krzysztof, > > On Tue, 15 Aug 2023 at 01:02, Krzysztof Kozlowski > <krzysztof.kozlowski@xxxxxxxxxx> wrote: >> >> On 11/08/2023 18:00, Naresh Solanki wrote: >>> Hi, >>> >>> On Tue, 8 Aug 2023 at 19:58, Conor Dooley <conor@xxxxxxxxxx> wrote: >>>> >>>> On Tue, Aug 08, 2023 at 07:10:08AM -0700, Guenter Roeck wrote: >>>>> On 8/8/23 04:46, Conor Dooley wrote: >>>>>> On Wed, Aug 02, 2023 at 09:31:51PM +0200, Naresh Solanki wrote: >>>>>>> From: Patrick Rudolph <patrick.rudolph@xxxxxxxxxxxxx> >>>>>>> >>>>>>> The TDA38640 chip has different output control mechanisms depending on >>>>>>> its mode of operation. When the chip is in SVID mode, only >>>>>>> hardware-based output control is supported via ENABLE pin. However, when >>>>>>> it operates in PMBus mode, software control works perfectly. >>>>>>> >>>>>>> To enable software control as a workaround in SVID mode, add the DT >>>>>>> property 'infineon,en-svid-control'. This property will enable the >>>>>>> workaround, which utilizes ENABLE pin polarity flipping for output when >>>>>>> the chip is in SVID mode. >>>>>> >>>>>> Why do you need a custom property for this? How come it is not possible >>>>>> to determine what bus you are on? >>>>>> >>>>> >>>>> That is not the point. Yes, it can be detected if the control method is >>>>> PMBus or SVID. However, in SVID mode, SVID is supposed to control the >>>>> output, not PMBUs. This is bypassed by controlling the polarity of the >>>>> (physical) output enable signal. We do _not_ want this enabled automatically >>>>> in SVID mode. Its side effects on random boards using this chip are unknown. >>>>> Thus, this needs a property which specifically enables this functionality >>>>> for users who _really_ need to use it and (hopefully) know what they are >>>>> doing. >>>> >>>> Hmm, reading this it makes a lot more sense why this is a property - I >>>> guess I just struggled to understand the commit message here, >>>> particularly what the benefit of using the workaround is. I'm still >>>> having difficulty parsing the commit & property text though - its >>>> unclear to me when you would need to use it - so I will stay out >>>> of the way & let Rob or Krzysztof handle things. >>> >>> To provide context, my system employs a unique power sequence >>> strategy utilizing a BMC (Baseboard Management Controller), >>> rendering the reliance on the ENABLE pin unnecessary. >>> In this configuration, the ENABLE pin is grounded in the hardware. >>> While most regulators facilitate PMBus Operation for output control, >>> the TDA38640 chip, when in SVID mode, is constrained by the >>> ENABLE pin to align with Intel specifications. >>> My communication with Infineon confirmed that the recommended >>> approach is to invert the Enable Pin for my use case. >>> >>> Since this is not typically the use case for most setup & hence DT property >>> is must for enabling the special case. >>> >>> For further insight into my setup's power sequence strategy, you can >>> refer to the following link: https://github.com/9elements/pwrseqd >>> >> >> This justifies to me the property, but still you described desired >> driver behavior, not the hardware characteristic. Don't describe what >> you want to control, but describe the entire system. > I guess by entire system you mean how the regulators(including > TDA38640) connected & operated in our setup ? I mean, property name and description should say what is the characteristic of the hardware/firmware/entire system. Best regards, Krzysztof
