On Thu, Oct 10, 2024 at 7:22 PM Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > > [...] > > > > > + > > > > + /* > > > > + * NOTE: > > > > + * Should we read Externsion Register to check power notification feature here? > > > > + */ > > > > > > Yes, this is needed too. > > > > > > > Hi, Ulf > > > > We have the call sd_can_poweroff_notify() in the _mmc_sd_suspend() and > > _sd_uhs2_suspend. > > If we need to check the power notification feature here, > > do you have any suggestions for the type of power notification that > > needs to be confirmed? > > Right, I see what you mean! It's been a while since I read these parts > of the SD spec, apologize for my ignorance. > > In UHS-II mode, the power-off-notification is *not* supported. This > means that we should not use it from _sd_uhs2_suspend(). > > In UHS-II mode we should instead use the so-called "hibernate" mode > (hbr bit in the GO_DORMANT command), which allows us to turn off > clocks and VDD1 (corresponds to the vmmc regulator). Note that the > support for hibernate mode is optional for an UHS-II SD card. Thus, > the support must be checked via the corresponding field in the PHY > capabilities, before we try to use it. > > That said, to not make it more complicated for you to get the basic > UHS-II support landed upstream, I am fine if you decide to defer the > support for hibernate mode to later. Instead, it seems like we should > just do a regular power-off in _sd_uhs2_suspend(). In other words, > just call sd_uhs2_power_off() from there. > > Moreover, reading the SD Extension Registers would still be valuable > during the UHS-II card initialization (even if hibernate isn't > supported), as it allows us to support the "cache maintenance" > feature, for example. However, the support for these features are > optional too for SD cards, so I am fine if you decide to defer this to > a later improvement too. > > Does this make sense to you? > > [...] > > Kind regards > Uffe Hi, Ulf I hope that this feature can be implemented later. Thanks, Victor Shih
