Re: FW: [PATCH v2] mmc: sdhci: apply voltage range check only for non-fixed regulators

[Marek Szyprowski <m.szyprowski@samsung.com>]

Hello,

On 11/14/2012 8:11 AM, Kevin Liu wrote:
> > From: linux-mmc-owner@vger.kernel.org [mailto:linux-mmc-owner@vger.kernel.org] On Behalf Of Chris Ball
> > Sent: Tuesday, November 13, 2012 10:14 PM
> > To: Marek Szyprowski
> > Cc: linux-kernel@vger.kernel.org; linux-mmc@vger.kernel.org; Kyungmin Park; Mark Brown; Liam Girdwood; Philip Rakity
> > Subject: Re: [PATCH v2] mmc: sdhci: apply voltage range check only for non-fixed regulators
> >
> > Hi,
> >
> > On Tue, Nov 13 2012, Marek Szyprowski wrote:
> >>> On Tue, Nov 13 2012, Marek Szyprowski wrote:
> >>> > Fixed regulators cannot change their voltage, so disable all voltage
> >>> > range checking for them, otherwise the driver fails to operate with
> >>> > fixed regulators. Up to now it worked only by luck, because
> >>> > regulator_is_supported_voltage() function returned incorrect values.
> >>> > Commit "regulator: fix voltage check in regulator_is_supported_voltage()"
> >>> > fixed that function and now additional check is needed for fixed
> >>> > regulators.
> >>> >
> >>> > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> >>> > ---
> >>> >  drivers/mmc/host/sdhci.c |    2 +-
> >>> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >>> >
> >>> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> >>> > index c7851c0..6f6534e 100644
> >>> > --- a/drivers/mmc/host/sdhci.c
> >>> > +++ b/drivers/mmc/host/sdhci.c
> >>> > @@ -2923,7 +2923,7 @@ int sdhci_add_host(struct sdhci_host *host)
> >>> >            regulator_enable(host->vmmc);
> >>> >
> >>> >  #ifdef CONFIG_REGULATOR
> >>> > -  if (host->vmmc) {
> >>> > +  if (host->vmmc && regulator_count_voltages(host->vmmc) > 1) {
> >>> >            ret = regulator_is_supported_voltage(host->vmmc, 3300000,
> >>> >                    3300000);
> >>> >            if ((ret <= 0) || (!(caps[0] & SDHCI_CAN_VDD_330)))
> >>>
> >>> Thanks for the longer explanation.  I'm still missing something, though;
> >>> what's wrong with running the check as it was with the new regulator code?
> >>> (I haven't tried it yet.)
> >>>
> >>> #ifdef CONFIG_REGULATOR
> >>>          if (host->vmmc) {
> >>>                  ret = regulator_is_supported_voltage(host->vmmc, 3300000,
> >>>                          3300000);
> >>>                  if ((ret <= 0) || (!(caps[0] & SDHCI_CAN_VDD_330)))
> >>>                          caps[0] &= ~SDHCI_CAN_VDD_330;
> >>>                  ret = regulator_is_supported_voltage(host->vmmc, 3000000,
> >>>                          3000000);
> >>>                  if ((ret <= 0) || (!(caps[0] & SDHCI_CAN_VDD_300)))
> >>>                          caps[0] &= ~SDHCI_CAN_VDD_300;
> >>>                  ret = regulator_is_supported_voltage(host->vmmc, 1800000,
> >>>                          1800000);
> >>>                  if ((ret <= 0) || (!(caps[0] & SDHCI_CAN_VDD_180)))
> >>>                          caps[0] &= ~SDHCI_CAN_VDD_180;
> >>>          }
> >>> #endif /* CONFIG_REGULATOR */
> >>>
> >>> The point is to remove unsupported voltages, so if someone sets up a
> >>> fixed regulator at 3300000, all of the other caps are disabled.  Why
> >>> wouldn't that work without this change, and how are we supposed to
> >>> remove those caps on a fixed regulator after your patchset?
> >>>
> >>> Thanks, sorry if I'm missing something obvious,
> >>
> >> On our boards eMMC is connected to fixed 2.8V regulator, what results in
> >> clearing all available voltages and fail. The same situation is when one
> >> enable dummy regulator and try to use sdhci with it. My patch fixes this
> >> and restores sdhci to working state as it was before (before fixing
> >> regulator regulator_is_supported_voltage() function and earlier when
> >> MMC_BROKEN_VOLATGE capability was used).
> >
> > I see.  Sounds like a separate bug -- Philip (or anyone else), any
> > idea how we should be treating eMMCs with a fixed voltage here?
> >
>
> I think we should check the voltage range rather than the voltage
> point accoring to the spec.
> Otherwise some valid voltage like 2.8v will be discarded by mistake.
> My below old patch aim to fix this issue.
> How do you think?
>
> -----Original Message-----
> From: Kevin Liu [mailto:keyuan.liu@gmail.com]
> Sent: Friday, September 28, 2012 3:56 PM
> To: linux-mmc@vger.kernel.org; cjb@laptop.org; pierre@ossman.eu;
> ulf.hansson@linaro.org; Zhangfei Gao
> Cc: Haojian Zhuang; Chao Xie; Philip Rakity; Kevin Liu; Jialing Fu
> Subject: [PATCH v5 03/13] mmc: sdhci: use regulator min/max voltage
> range according to spec
>
> From: Kevin Liu <kliu5@marvell.com>
>
> For regulator vmmc/vmmcq, use voltage range as below
> 3.3v/3.0v: (2.7v, 3.6v)
> 1.8v: (1.7v, 1.95v)
> Original code use the specific value which may fail in regulator
> driver if it does NOT support the specific voltage.
>
> Signed-off-by: Jialing Fu <jlfu@marvell.com>
> Signed-off-by: Kevin Liu <kliu5@marvell.com>

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>

This patch restores sdhci devices to working state on Samsung boards
(tested on GONI and UniversalC210) after merging "regulator: fix voltage
check in regulator_is_supported_voltage()" patch to v3.7-rc6 (commit
f0f98b19e23d4426ca185e3d4ca80e6aff5ef51b). Would be great to have it
merged before the final v3.7 is out.

> ---
>   drivers/mmc/host/sdhci.c |   16 +++++++---------
>   1 files changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 3aef580..36afd47 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1628,7 +1628,7 @@ static int
> sdhci_do_3_3v_signal_voltage_switch(struct sdhci_host *host,
>   	sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
>
>   	if (host->vqmmc) {
> -		ret = regulator_set_voltage(host->vqmmc, 3300000, 3300000);
> +		ret = regulator_set_voltage(host->vqmmc, 2700000, 3600000);
>   		if (ret) {
>   			pr_warning("%s: Switching to 3.3V signalling voltage "
>   				   " failed\n", mmc_hostname(host->mmc));
> @@ -1672,7 +1672,7 @@ static int
> sdhci_do_1_8v_signal_voltage_switch(struct sdhci_host *host,
>   		 */
>   		if (host->vqmmc)
>   			ret = regulator_set_voltage(host->vqmmc,
> -				1800000, 1800000);
> +				1700000, 1950000);
>   		else
>   			ret = 0;
>
> @@ -2856,7 +2856,7 @@ int sdhci_add_host(struct sdhci_host *host)
>   		pr_info("%s: no vqmmc regulator found\n", mmc_hostname(mmc));
>   		host->vqmmc = NULL;
>   	}
> -	else if (regulator_is_supported_voltage(host->vqmmc, 1800000, 1800000))
> +	else if (regulator_is_supported_voltage(host->vqmmc, 1700000, 1950000))
>   		regulator_enable(host->vqmmc);
>   	else
>   		caps[1] &= ~(SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 |
> @@ -2927,16 +2927,14 @@ int sdhci_add_host(struct sdhci_host *host)
>
>   #ifdef CONFIG_REGULATOR
>   	if (host->vmmc) {
> -		ret = regulator_is_supported_voltage(host->vmmc, 3300000,
> -			3300000);
> +		ret = regulator_is_supported_voltage(host->vmmc, 2700000,
> +			3600000);
>   		if ((ret <= 0) && (caps[0] & SDHCI_CAN_VDD_330))
>   			caps[0] &= ~SDHCI_CAN_VDD_330;
> -		ret = regulator_is_supported_voltage(host->vmmc, 3000000,
> -			3000000);
>   		if ((ret <= 0) && (caps[0] & SDHCI_CAN_VDD_300))
>   			caps[0] &= ~SDHCI_CAN_VDD_300;
> -		ret = regulator_is_supported_voltage(host->vmmc, 1800000,
> -			1800000);
> +		ret = regulator_is_supported_voltage(host->vmmc, 1700000,
> +			1950000);
>   		if ((ret <= 0) && (caps[0] & SDHCI_CAN_VDD_180))
>   			caps[0] &= ~SDHCI_CAN_VDD_180;
>   	}

Best regards
-- 
Marek Szyprowski
Samsung Poland R&D Center