On Wed, 2015-05-06 at 10:44 +0200, Ulf Hansson wrote: > On 6 May 2015 at 03:38, Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx> wrote: > > On Tue, 2015-05-05 at 10:47 +0200, Ulf Hansson wrote: > >> On 5 May 2015 at 10:35, Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx> wrote: > >> > On 05/05/15 10:56, Ulf Hansson wrote: > >> >> On 30 April 2015 at 14:32, Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx> wrote: > >> >>> Implement voltage switch, supporting modes up to SDR-50. > >> >>> > >> >>> Based on work by Shinobu Uehara, Rob Taylor, William Towle and Ian Molton. > >> >>> > >> >>> This uses two voltage regulators, one external and one on the pfc. > >> >> > >> >> Why two? If there is a parent child relation ship, that should be > >> >> handled through the regulator tree, right!? Please elaborate. > >> > > >> > The card main power is separate from the IO line voltages. > >> > > >> > To get to the high-speed, card power is left at 3.3V and the IO > >> > voltage is changed to 1.8V. > >> > > >> > In the systems we have the power gate is separate from the controls > >> > for the IO but not integrated into the MMC controller itself. > > > > In this case, there are *three* regulators: > > > > 1. External regulator for card power (VDD pin): "vmmc" > > 2. External regulator for pull-up voltage for the data pins: "vqmmc" > > Is this really a regulator and not just about changing a pinctrl setting? Looking at the Lager board, the pull-up voltage appears to be controlled by the external PMIC (DA9063), which is signalled using GPIOs (I don't know why, when it's also connected to I2C). > The reason why I wonder, is because there are several other mmc host > driver's the use a specific pinctrl state for this. > > > 3. Internal regulator for input(?) level on the data pins: > > "vqmmc_ref" (I'm open to suggestions of a better name) This one is implemented in the pinctrl (pfc) block. [...] > >> 3) The voltage levels changes for vmmc shall be handled via the > >> ->set_ios() callback. > > > > We don't support UHS-II so we never change the voltage of this > > regulator. > > That's not related to UHS-II. Voltage level negotiation for vmmc is > done even for legacy mode cards. I'm looking at "SD Specifications, Part 1, Physical Layer Simplified Specifications, Version 4.10" and it seems clear from that, that only UHS-II cards have a variable supply voltage. Maybe that changed in a later version? Anyway, I don't have any board that can change the supply voltage. Ben. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
