On 12 January 2017 at 05:43, Matt Ranostay <matt@ranostay.consulting> wrote: > On Wed, Jan 11, 2017 at 2:55 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: >> On 9 January 2017 at 05:53, Matt Ranostay <matt@ranostay.consulting> wrote: >>> On Fri, Dec 30, 2016 at 12:05 AM, Linus Walleij >>> <linus.walleij@xxxxxxxxxx> wrote: >>>> On Mon, Dec 19, 2016 at 1:01 AM, Matt Ranostay <matt@ranostay.consulting> wrote: >>>> >>>>> * SD8787 has a "powerdown" line, and CW1200 has a "powerup" line.. I >>>>> know this is a simple logic inversion. >>>> >>>> If this is a GPIO line, the GPIO subsystem can flag a line for >>>> inverted logic. GPIO_ACTIVE_LOW from device tree for example. >>> >>> Slight ping on Ulf on this thread :). >> >> Thanks, sorry for the delay! >> >>> >>> I do understand the inverted logic flag but that doesn't help if there >>> are different logic states between various chipsets. >> >> For cw1200 (I looked at code from an old ST-Ericsson vendor tree), the >> sequence is as follows: >> >> 1) Enable clock/power to the card/chip. >> 2) Assert GPIO pin. I assume this also can be done before the >> clock/power is enabled. >> 3) Wait some time (~50ms). >> 4) De-assert GPIO pin. >> 5) Wait some time (~20ms) >> 6) Assert GPIO pin. >> 7) Wait some time (~32ms). >> >> At power off, the GPIO pin is de-asserted and of course also the >> clock/power is disabled. Just to make sure we have all the relevant >> logic. >> >> Looking at mmc pwrseq simple, perhaps we can extend this to deal with >> GPIOs that needs to be *toggled*, as this is not just reset GPIOs. >> Then we also need to deal with the delays in-between the toggling. > > Wouldn't we need to have a per chip function for each device > supported? As well document gpios? I suspect we'd need an array of I was hoping to avoid this, but the more I look at it, it seems inevitable. > gpios defined in device tree since different devices will likely have > various numbers of pins to toggle Maybe we can think of a clever way to combine cw1200 with your case? Perhaps a "mmc pwrseq toggle". :-) If not, please go ahead an repost a device specific mmc pwrseq for your case. I realize this would be a good opportunity for me to work on enabling support for cw1200 on ux500, but as the implementation of the clock/power control also needs to be up-streamed, I am quite far from being done. Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
