On 03.09.2024 10:18, Biju Das wrote: > Hi Claudiu, > >> -----Original Message----- >> From: Biju Das >> Sent: Monday, September 2, 2024 11:48 AM >> Subject: RE: [PATCH 00/16] Add initial USB support for the Renesas RZ/G3S SoC >> >> Hi Claudiu, >> >>> -----Original Message----- >>> From: claudiu beznea <claudiu.beznea@xxxxxxxxx> >>> Sent: Monday, September 2, 2024 11:41 AM >>> Subject: Re: [PATCH 00/16] Add initial USB support for the Renesas >>> RZ/G3S SoC >>> >>> >>> >>> On 02.09.2024 12:18, Biju Das wrote: >>>>>>>> Do you have any plan to control this power transitions(ALL_ON to AWO and vice versa) in linux? >>>>>>> As you know, the RZ/G3S USB PM code is already prepared. This is >>>>>>> also configuring these signals when going to suspend/exiting from resume. >>>>>>> W/o configuring properly these signals the USB is not working after a suspend/resume cycle. >>>>>> One option is to handle SYSC USB PWRRDY signal in TF-A, if you >>>>>> plan to handle system transitions >>>>> there?? >>>>> >>>>> As I mentioned, the settings in these registers may be changed by >>>>> intermediary booting >>> applications. >>>>> Depending on that, Linux need to control it also on probe for USB >>>>> to work (it should be the same with PCIe, these signals seems similar from HW manual >> description). >>>> You mean system transition settings will be override by U-boot, so Linux needs to restore it >> back?? >>> >>> It was talking about booting... >> >> I am also referring to boot. Boot starts with TF-A and it has a system state. >> >>> >>> You proposed to handle SYSC signals from TF-A in a discussion about system power transitions: >>> >>> "One option is to handle SYSC USB PWRRDY signal in TF-A, if you plan to handle system transitions" >>> >>> (I was guessing the "system transition" statement there refers to >>> power states transitions, ALL_ON <-> >>> AWO/VBAT) >> >> That is correct. >> >>> >>> and I gave the booting process as a counter example: if we handle it >>> in TF-A it may not be enough as these signals might be changed by intermediary booting applications >> (e.g., U-Boot). >> >> Why should U-boot override, system state signals such as USB PWRREADY? Can you please give an example. >> >>> >>> To conclude, there are 3 scenarios I see where these signals need to >>> be >>> handled: >>> 1/ booting >>> 2/ suspend to RAM >>> 3/ driver unbind/bind >> >> --> It should be OK as linux is not handling USB PWRREADY signal. >> >>> >>> In case of booting: if we have TF-A to set signals there might be >>> intermediary booting applications (e.g. U-Boot) that set these signals >>> also. If it leaves it in improper state and Linux wants to use USB then the USB will not work (if >> Linux doesn't handle it). >> >> That is the problem of U-boot. U-boot should not override system state signals such as USB PWRREADY. >> >>> >>> In case of suspend to RAM: as TF-A is the only application in the >>> suspend to RAM chain, it should work handling it in TF-A. >> >> That is correct, TF-A should handle based on system state. >> >>> >>> In case of unbind/bind: currently we don't know if these signals >>> introduces any kind of power saving so asserting/de-asserting them in Linux may be useful from this >> perspective, if any. >> >> These are system signals, according to me should not be used in unbind/bind. >> >> I may be wrong. > > Just to add the below are the 4 system states (power mode) for this LSI. > > If I understand correctly, we need to configure USB PWRRDY signal > only when there is a transition from ALL_ON to AWO mode and vice versa. > as you see on AWO mode only CM-33 is active. > > • ALL_OFF mode: All CPUs and peripheral modules can not be worked. > • ALL_ON mode: All CPUs and peripheral modules can be worked. > • AWO mode: Cortex-M33 and peripheral modules in PD_VCC and PD_VBATT domain can be worked. > • VBATT mode: Only RTC, tamper detection and backup registers can be worked. > > System manager which is controlling both CA-55 and CM-33, will set USB PWRRDY signal > based on system state. > > Since we don't have system manager for controlling both CA-55 and CM-33 > Probably from CA-55 perspective, TF-A should be sufficient. > > During boot clr USB PWR READY signal in TF-A. > STR case, suspend set USB PWR READY signal in TF-A. > STR case, resume clr USB PWR READY signal in TF-A. As I said previously, it can be done in different ways. My point was to let Linux set what it needs for all it's devices to work. I think the way to go forward is a maintainer decision. Thank you, Claudiu Beznea > > I am not expert in this area. I may be wrong. > > Maybe we need to get an opinion from Power experts in Linux. > > Cheers, > Biju
