On 5 June 2015 at 10:49, Lu Y.B. <[email protected]> wrote: >> On 5 June 2015 at 10:10, Lu Y.B. <[email protected]> wrote: >> >> >> On 2 June 2015 at 09:09, Yangbo Lu <[email protected]> wrote: >> >> >> > This quirk is used for controllers that can only support 1.8V >> >> >> > voltage but the peripheral hardware circuit has capability to >> >> >> > support 3.3V voltage. >> >> >> >> >> >> Which voltage are you referring to? The I/O voltage or the power >> >> >> to the card? VCC or VCCQ? >> >> >> >> >> >> Kind regards >> >> >> Uffe >> >> > >> >> > The voltage here means I/O voltage. >> >> > Although the controller only supports 1.8v, the hardware circuit >> >> > has a >> >> level translator for supporting 3.3v. >> >> >> >> Thanks for clarifying. >> > >> > Sorry, it should be power voltage... >> > This quirk is used to set capability register "Voltage Support 3.3V" >> bit since the controller self doesn’t support but circuit supports. >> > >> >> Okay. >> >> So then please tell me, exactly, how is the power being controlled when >> using this "hardware circuit"? >> >> This patchset only tries to change the content of the ocr_mask, but there >> is no logic added to support changing voltage levels by using the >> "external circuit". At least to my understanding. >> > > As I said, the controller only support 1.8v but we could use adapter card or > add level translator on board directly to make sd *only* work on 3.3v power > and 3.3v IO voltage. > Thanks.
How does this level translator work? Doesn't it need to be controlled somehow? Do you have a datasheet you can share for it? Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
