Hi, On Tue, Apr 26, 2022 at 2:16 AM Srinivasarao Pathipati <quic_spathi@xxxxxxxxxxx> wrote: > > From: Sayali Lokhande <sayalil@xxxxxxxxxxxxxx> > > While switching from hs400 to hs200 mode, high speed mode > timing should be selected in the device before changing the > clock frequency in the host. But current implementation, > (mmc_hs400_to_hs200) first updates the frequency in the host > and then updates mode in the device. This is a spec violation. > Hence update the sequence to comply with the spec. I'm a bit new to interpreting eMMC specs, but are you sure this is a violation? In JESD84-B51, I see: "The bus frequency can be changed at any time (under the restrictions of maximum data transfer frequency, defined by the Device, and the identification frequency defined by the standard document)." I think that suggests we can lower the host clock first, and then lower the device timing. And (according to my limited knowledge) that makes sense too: the device timing is a "maximum" (to some extent) and we're free to run the host bus somewhat slower. And on the flip side: it sounds like you may be _introducing_ a spec violation (that we'll be running the host faster than the device timing, briefly)? Apologies if I'm off base. But you did CC me ;) Regards, Brian
