On Wed, 2024-03-27 at 12:55 +0100, Alexandre Mergnat wrote: > > External email : Please do not click links or open attachments until > you have verified the sender or the content. > Hello Yu-chang Lee, > > SMI LARB must have a power domain, according to "mediatek,smi- > larb.yaml" > Now you try to create a link from power domain to larb. > > Here is my understanding: when you enable/disable power domain, the > larb linked to this power domain may have an issue. Then you want to > retrieve de LARB linked to the power domain though the dts to manage > the LARB. Yes, this is what I am trying to do. > IMHO, using the dts to have this information into the power > driver isn't necessary and may introduce some bugs if the LARB node > and power node in the DTS aren't aligned. > > It seems not implemented today but during the LARB probe, it should > "subscribe" to the linked power domain. Then, when the power domain > status is changing, it is able to "notify" (callback) the LARB, then > implement the good stuff to handle this power domain status change > into LARB driver. > The problem with this method and why "smi clamp" is in power domain driver is that our HW designer gave us a programming guide strictly states the sequence of what we need to do to power on/off power domain. Using callback, this sequence is no longer guaranteed and the side effect is unknown... So I would like to stick with adding larbs just like smi into power domain node. > Regards, > Alexandre Best Regards, Yu-chang > > On Wed, Mar 27, 2024 at 12:04 PM Krzysztof Kozlowski > <krzysztof.kozlowski@xxxxxxxxxx> wrote: > > > > On 27/03/2024 11:56, Yu-chang Lee (李禹璋) wrote: > > > On Wed, 2024-03-27 at 11:43 +0100, Krzysztof Kozlowski wrote: > > >> > > >> External email : Please do not click links or open attachments > until > > >> you have verified the sender or the content. > > >> On 27/03/2024 11:39, Yu-chang Lee (李禹璋) wrote: > > >>>>>> > > >>>>> Hi, > > >>>>> > > >>>>> I will double check the format of yaml for the next version, > > >> sorry > > >>>> for > > >>>>> inconvenience. But I did test it on mt8188 chromebook, the > reason > > >>>> why > > >>>> > > >>>> How do you test a binding on chromebook? > > >>>> > > >>>>> power domain need larb node is that when mtcmos power on, > signal > > >>>> glitch > > >>>>> may produce. Power domain driver must reset larb when this > happen > > >>>> to > > >>>>> prevent dummy transaction on bus. That why I need larb node > in > > >> dts. > > >>>> > > >>>> No one talks here about larb node... > > >>> > > >>> Sorry, May you elaborate on what information I need to provide > to > > >> you > > >>> or it is just a syntax problem I need to fix? > > >> > > >> Please explain the purpose of this property (how is it going to > be > > >> used by drivers)and what does it represent. > > >> > > > > > > It represent SMI LARB(Local ARBitration). In power domain driver > when > > > power on power domain, It need to reset LARB to prevent potential > power > > > glitch which may cause dummy transaction on bus. Without taking > care of > > > this issue it often leads to camera hang in stress test. > > > > That sounds rather like missing resets... or something else > connecting > > these devices. Maybe the explanation is just imprecise... > > > > Best regards, > > Krzysztof > > > >
