| Message ID | 1421240530-7971-3-git-send-email-ulf.hansson@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 15 January 2015 at 17:58, Mark Rutland <mark.rutland@arm.com> wrote: > Hi Ulf, > > On Wed, Jan 14, 2015 at 01:02:08PM +0000, Ulf Hansson wrote: >> The simple MMC power sequence provider, intends to supports a set of >> common properties between SOC designs. It thus enables us to re-use the >> same provider for several SOCs. >> >> In this initial step, let's add the top level description of the MMC >> power sequence and describe the compatible string for the simple MMC >> power sequence provider. >> >> Following patches will step by step add support for new properties to >> the simple MMC power sequence provider. >> >> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> >> --- >> >> Changes in v2: >> - None. >> >> --- >> .../devicetree/bindings/mmc/mmc,pwrseq-simple.txt | 18 ++++++++++++++++++ >> Documentation/devicetree/bindings/mmc/mmc.txt | 5 +++++ >> 2 files changed, 23 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt >> >> diff --git a/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt b/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt >> new file mode 100644 >> index 0000000..e1b7f9c >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt >> @@ -0,0 +1,18 @@ >> +* The simple MMC power sequence provider >> + >> +System on chip designs may specify a specific MMC power sequence. To >> +successfully detect an (e)MMC/SD/SDIO card, that power sequence must be >> +maintained while initializing the card. >> + >> +The simple MMC power sequence provider, intends to supports a set of common >> +properties between SOC designs. It thus enables us to re-use the same provider >> +for several SOC designs. >> + >> +Required properties: >> +- compatible : contains "mmc,pwrseq-simple". > > Nit: "mmc" is not a vendor prefix. > >> + >> +Example: >> + >> + sdhci0_pwrseq { >> + compatible = "mmc,pwrseq-simple"; >> + } > > I'm a little confused here. What specific sequence is described by this > node? We don't appear to have referred to any resources used as part of > that sequence, and the description above only mentions that there could > be a specific sequence, not what that sequence is. > > So I don't think this makes sense on its own, and should probably be > folded with patches adding the initial support for the resources used as > part of the sequence (e.g. the GPIOs added in a later patch). You are absolutely right. I fix it. Again, thanks for reviewing. Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 15 January 2015 at 19:53, NeilBrown <neilb@suse.de> wrote: > On Thu, 15 Jan 2015 16:58:26 +0000 Mark Rutland <mark.rutland@arm.com> wrote: > >> Hi Ulf, >> >> On Wed, Jan 14, 2015 at 01:02:08PM +0000, Ulf Hansson wrote: >> > The simple MMC power sequence provider, intends to supports a set of >> > common properties between SOC designs. It thus enables us to re-use the >> > same provider for several SOCs. >> > >> > In this initial step, let's add the top level description of the MMC >> > power sequence and describe the compatible string for the simple MMC >> > power sequence provider. >> > >> > Following patches will step by step add support for new properties to >> > the simple MMC power sequence provider. >> > >> > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> >> > --- >> > >> > Changes in v2: >> > - None. >> > >> > --- >> > .../devicetree/bindings/mmc/mmc,pwrseq-simple.txt | 18 ++++++++++++++++++ >> > Documentation/devicetree/bindings/mmc/mmc.txt | 5 +++++ >> > 2 files changed, 23 insertions(+) >> > create mode 100644 Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt >> > >> > diff --git a/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt b/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt >> > new file mode 100644 >> > index 0000000..e1b7f9c >> > --- /dev/null >> > +++ b/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt >> > @@ -0,0 +1,18 @@ >> > +* The simple MMC power sequence provider >> > + >> > +System on chip designs may specify a specific MMC power sequence. To >> > +successfully detect an (e)MMC/SD/SDIO card, that power sequence must be >> > +maintained while initializing the card. >> > + >> > +The simple MMC power sequence provider, intends to supports a set of common >> > +properties between SOC designs. It thus enables us to re-use the same provider >> > +for several SOC designs. >> > + >> > +Required properties: >> > +- compatible : contains "mmc,pwrseq-simple". >> >> Nit: "mmc" is not a vendor prefix. >> >> > + >> > +Example: >> > + >> > + sdhci0_pwrseq { >> > + compatible = "mmc,pwrseq-simple"; >> > + } >> >> I'm a little confused here. What specific sequence is described by this >> node? We don't appear to have referred to any resources used as part of >> that sequence, and the description above only mentions that there could >> be a specific sequence, not what that sequence is. >> >> So I don't think this makes sense on its own, and should probably be >> folded with patches adding the initial support for the resources used as >> part of the sequence (e.g. the GPIOs added in a later patch). >> > > I guess I assumed that this "simple" referred to the current behaviour, which > includes some of vmmc-supply, vqmmc-supply, vmmc_aux-supply and pbias-supply > being switched at "appropriate" times. > > Would it make sense to bring all of these explicitly under the "pwrseq" > umbrella, leaving the current behaviour only when no pwrseq node is provided? In principle there is nothing that prevents us from following your suggestion. But why should we? Moreover, I don't think it's required at this point, let's first get the basic mmc-pwrseq support in place. Then we can evolve it. :-) > > Also, it isn't clear to me whether the need for power/reset is a function of > the mmc-host, or a function of the device attached to the host. I suspect > some are needed by one, some by the other. Any by both? To me the the power is coupled with the host and thus controlled by the mmc layer. But I guess we can discuss this in a forever long loop. :-) They may be other resources which is coupled with an SDIO function / eMMC,SDIO card, such as irqs. Those shall be described in the child node of the host. I have queued the below patchset from Hans, which I believe should address this: https://www.mail-archive.com/linux-mmc@vger.kernel.org/msg27241.html > > Should the two needs be kept separate? Yes, I think so. Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt b/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt new file mode 100644 index 0000000..e1b7f9c --- /dev/null +++ b/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt @@ -0,0 +1,18 @@ +* The simple MMC power sequence provider + +System on chip designs may specify a specific MMC power sequence. To +successfully detect an (e)MMC/SD/SDIO card, that power sequence must be +maintained while initializing the card. + +The simple MMC power sequence provider, intends to supports a set of common +properties between SOC designs. It thus enables us to re-use the same provider +for several SOC designs. + +Required properties: +- compatible : contains "mmc,pwrseq-simple". + +Example: + + sdhci0_pwrseq { + compatible = "mmc,pwrseq-simple"; + } diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt index bac1311..b12de1e 100644 --- a/Documentation/devicetree/bindings/mmc/mmc.txt +++ b/Documentation/devicetree/bindings/mmc/mmc.txt @@ -64,6 +64,10 @@ Optional SDIO properties: - keep-power-in-suspend: Preserves card power during a suspend/resume cycle - enable-sdio-wakeup: Enables wake up of host system on SDIO IRQ assertion +Optional MMC power sequence: +- mmc-pwrseq: phandle to the MMC power sequence node. See "mmc,pwrseq-*" + for documentation of MMC power sequence bindings. + Use of Function subnodes ------------------------ @@ -101,6 +105,7 @@ sdhci@ab000000 { max-frequency = <50000000>; keep-power-in-suspend; enable-sdio-wakeup; + mmc-pwrseq = <&sdhci0_pwrseq> } Example with sdio function subnode:
The simple MMC power sequence provider, intends to supports a set of common properties between SOC designs. It thus enables us to re-use the same provider for several SOCs. In this initial step, let's add the top level description of the MMC power sequence and describe the compatible string for the simple MMC power sequence provider. Following patches will step by step add support for new properties to the simple MMC power sequence provider. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> --- Changes in v2: - None. --- .../devicetree/bindings/mmc/mmc,pwrseq-simple.txt | 18 ++++++++++++++++++ Documentation/devicetree/bindings/mmc/mmc.txt | 5 +++++ 2 files changed, 23 insertions(+) create mode 100644 Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt