Hi Claudiu, > -----Original Message----- > From: claudiu beznea <claudiu.beznea@xxxxxxxxx> > Sent: Tuesday, September 3, 2024 11:25 AM > Subject: Re: [PATCH 00/16] Add initial USB support for the Renesas RZ/G3S SoC > > > > 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. I agree, there can be n number of solution for a problem. Since you modelled system state signal (USB PWRRDY) as reset control signal, it is reset/DT maintainer's decision to say the final word whether this signal fits in reset system framework or not? Cheers, biju
