Adrian,
On Wed, Sep 16, 2020 at 09:42:28AM +0300, Adrian Hunter wrote:
> On 15/09/20 9:24 am, AKASHI Takahiro wrote:
> > Adrain,
> >
> > On Mon, Sep 14, 2020 at 09:36:02AM +0300, Adrian Hunter wrote:
> >> On 14/09/20 8:45 am, AKASHI Takahiro wrote:
> >>> Adrian,
> >>>
> >>> On Fri, Aug 21, 2020 at 05:11:18PM +0300, Adrian Hunter wrote:
> >>>> On 10/07/20 2:11 pm, Ben Chuang wrote:
> >>>>> From: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
> >>>>>
> >>>>> VDD2 is used for powering UHS-II interface.
> >>>>> Modify sdhci_set_power_and_bus_voltage(), sdhci_set_power_noreg()
> >>>>> and sdhci_set_power_noreg() to handle VDD2.
> >>>>
> >>>> vdd2 is always 1.8 V and I suspect there may never be support for anything
> >>>> else, so we should start with 1.8 V only.
> >>>
> >>> What do you mean here?
> >>> You don't want to add an extra argument, vdd2, to sdhci_set_power().
> >>> Correct?
> >>
> >> Yes
> >>
> >>>
> >>>> Also can we create uhs2_set_power_reg() and uhs2_set_power_noreg() and use
> >>>> the existing ->set_power() callback
> >>>
> >>> Again what do you expect here?
> >>>
> >>> Do you want to see any platform-specific mmc driver who supports UHS-II
> >>> to implement its own call back like:
> >>
> >> Not exactly. I expect there to be a common implementation in sdhci-uhs2.c
> >> called sdhci_uhs2_set_power() for example, that drivers can use by setting
> >> their .set_power = sdhci_uhs2_set_power. If they need platform-specific
> >> code as well then their platform-specific code can call
> >> sdhci_uhs2_set_power() if desired.
> >>
> >>>
> >>> void sdhci_foo_set_power(struct sdhci_host *host, unsigned char mode,
> >>> unsigned short vdd)
> >>> {
> >>> sdhci_set_power(host, mode,vdd);
> >>>
> >>> /* in case that sdhci_uhs2 module is not inserted */
> >>> if (!(mmc->caps & MMC_CAP_UHS2))
> >>> return;
> >>>
> >>> /* vdd2 specific operation */
> >>> if (IS_ERR_OR_NULL(host->mmc->supply.vmmc2))
> >>> sdhci_uhs2_set_power_noreg(host, mode);
> >>> else
> >>> sdhci_uhs2_set_power_reg(host, mode);
> >>>
> >>> /* maybe more platform-specific initialization */
> >>> }
> >>>
> >>> struct sdhci_ops sdhci_foo_ops = {
> >>> .set_power = sdhci_foo_set_power,
> >>> ...
> >>> }
> >
> > What do you think about this logic in general?
> > (If necessary, read it replacing "foo" to "uhs2".)
> >
> > What I'm concerned about is SDHCI_POWER_CONTROL register.
> > Vdd and vdd2 are controlled with corresponding bits in this register.
> > It seems to be "natural" to me that vdd and vdd2 are enabled
> > in a single function rather than putting them in separate ones.
> >
> > In particular, in the case of sdhci_set_power_noreg(), there exist a couple
> > of "quirks" around writing the bits to SDHCI_POWER_CONTROL register.
>
> We can treat UHS-II support as being for new hardware and therefore
> we don't necessarily need to support old quirks. Just make sure if
> a quirk is not being supported, to add a comment to that effect.
>
> > I don't know how we should handle them if we have a separate function,
> > say, sdhci_uhs2_set_power_noreg().
> > Do you want to see a copy of the same logic in sdhci_uhs2_set_power_noreg()?
>
> I would probably consider making another function that non-UHS-II
> drivers do not need to care about e.g. existing drivers can keep using
> sdhci_set_power_noreg() and sdhci_uhs2 can call __sdhci_set_power_noreg()
Well, but
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 592a55a34b58..ffe54f06fe38 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2013,8 +2013,8 @@ static void sdhci_set_power_reg(struct sdhci_host *host, unsigned char mode,
> sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
> }
>
> -void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
> - unsigned short vdd)
> +void __sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
> + unsigned short vdd, u8 vdd2)
> {
> u8 pwr = 0;
>
> @@ -2048,7 +2048,7 @@ void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
> if (host->pwr == pwr)
> return;
>
> - host->pwr = pwr;
> + host->pwr = pwr | vdd2;
(the line above is wrong, but anyway)
we must also set
if (vdd2)
pwr |= SDHCI_VDD2_POWER_ON;
As a result, this new function is the almost exact same as the corresponding one
in our v3 patch, except its name.
Now do you allow such a small piece of UHS-II specific code to be
placed in sdhci.c?
-Takahiro Akashi
> if (pwr == 0) {
> sdhci_writeb(host, 0, SDHCI_POWER_CONTROL);
> @@ -2085,6 +2085,13 @@ void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
> mdelay(10);
> }
> }
> +EXPORT_SYMBOL_GPL(__sdhci_set_power_noreg);
> +
> +void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
> + unsigned short vdd)
> +{
> + __sdhci_set_power_noreg(host, mode, vdd, 0);
> +}
> EXPORT_SYMBOL_GPL(sdhci_set_power_noreg);
>
> void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
>
> >
> > -Takahiro Akashi
> >
> >
> >>>
> >>> Is this what you mean?
> >>> (I'm not quite sure yet that sdhci_ush2_set_power_noreg() can be split off
> >>> from sdhci_set_power_noreg().)
> >>>
> >>> -Takahiro Akashi
>
