On 2 January 2015 at 17:14, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote: > This is yet another try to solve the issues of dealing with power sequences for > the MMC subsystem. The latest attempt, see link below, took a generic approach > by adding a new top level driver layer. That's was rejected by several reasons. > http://lwn.net/Articles/602855/ > > This time the approach is focused to fix the issues for MMC only. > > To give a short background, SOCs may specify a specific MMC power sequence. To > successfully detect an (e)MMC/SD/SDIO card, that power sequence must be followed > while initializing the card. Hi Ulf, have used this to successfully init a mwifiex_sdio card but had to also add a delay while the reset line is asserted. May make sense to add a property to the pwrseq node to specify the minimum amount of time that the reset GPIO needs to be asserted? Tested-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx> Thanks, Tomeu > To be able to handle these SOC specific power sequences, we add a MMC power > sequence interface, which helps the mmc core to deal with such. > > A MMC power sequence provider then implements a set of callbacks from the above > mentioned interface. The provider has a corresponding DT compatibility string > and relies on CONFIG_OF to be set to find it's various resourses, like for > example a GPIO reset. > > The mmc core will from mmc_of_parse() try find a "mmc-pwrseq" DT node and then > call the corresponding MMC power sequence provider's initialization function. > > > Ulf Hansson (4): > mmc: core: Initial support for MMC power sequences > mmc: pwrseq: Document DT bindings for the simple MMC power sequence > mmc: pwrseq: Initial support for the simple MMC power sequence > provider > mmc: pwrseq_simple: Add support for a reset GPIO pin > > .../devicetree/bindings/mmc/mmc,pwrseq-simple.txt | 23 +++++ > Documentation/devicetree/bindings/mmc/mmc.txt | 5 + > drivers/mmc/core/Makefile | 2 +- > drivers/mmc/core/core.c | 7 ++ > drivers/mmc/core/host.c | 4 +- > drivers/mmc/core/pwrseq.c | 109 +++++++++++++++++++++ > drivers/mmc/core/pwrseq.h | 42 ++++++++ > drivers/mmc/core/pwrseq_simple.c | 86 ++++++++++++++++ > include/linux/mmc/host.h | 2 + > 9 files changed, 278 insertions(+), 2 deletions(-) > create mode 100644 Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt > create mode 100644 drivers/mmc/core/pwrseq.c > create mode 100644 drivers/mmc/core/pwrseq.h > create mode 100644 drivers/mmc/core/pwrseq_simple.c > > -- > 1.9.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- 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
