Messages in this thread | | | Subject | Re: [PATCH V2 1/2] mmc: sdhci-msm: Add support to store supported vdd-io voltages | From | Jeremy McNicoll <> | Date | Thu, 22 Mar 2018 01:04:07 -0700 |
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On 2018-03-19 5:32 AM, Vijay Viswanath wrote: > > > On 3/7/2018 9:42 PM, Doug Anderson wrote: >> Hi, >> >> On Tue, Mar 6, 2018 at 11:13 PM, Vijay Viswanath >> <vviswana@codeaurora.org> wrote: >>> Hi Dough, Jeremy, >>> >>> >>> On 3/3/2018 4:38 AM, Jeremy McNicoll wrote: >>>> >>>> On 2018-03-02 10:23 AM, Doug Anderson wrote: >>>>> >>>>> Hi, >>>>> >>>>> On Sun, Feb 11, 2018 at 10:01 PM, Vijay Viswanath >>>>> <vviswana@codeaurora.org> wrote: >>>>>> >>>>>> During probe check whether the vdd-io regulator of sdhc platform >>>>>> device >>>>>> can support 1.8V and 3V and store this information as a capability of >>>>>> platform device. >>>>>> >>>>>> Signed-off-by: Vijay Viswanath <vviswana@codeaurora.org> >>>>>> --- >>>>>> drivers/mmc/host/sdhci-msm.c | 38 >>>>>> ++++++++++++++++++++++++++++++++++++++ >>>>>> 1 file changed, 38 insertions(+) >>>>>> >>>>>> diff --git a/drivers/mmc/host/sdhci-msm.c >>>>>> b/drivers/mmc/host/sdhci-msm.c >>>>>> index c283291..5c23e92 100644 >>>>>> --- a/drivers/mmc/host/sdhci-msm.c >>>>>> +++ b/drivers/mmc/host/sdhci-msm.c >>>>>> @@ -23,6 +23,7 @@ >>>>>> #include <linux/iopoll.h> >>>>>> >>>>>> #include "sdhci-pltfm.h" >>>>>> +#include <linux/regulator/consumer.h> >>>>> >>>>> >>>>> This is a strange sort order for this include file. Why is it after >>>>> the local include? >>>>> >>>>> >>>>>> #define CORE_MCI_VERSION 0x50 >>>>>> #define CORE_VERSION_MAJOR_SHIFT 28 >>>>>> @@ -81,6 +82,9 @@ >>>>>> #define CORE_HC_SELECT_IN_HS400 (6 << 19) >>>>>> #define CORE_HC_SELECT_IN_MASK (7 << 19) >>>>>> >>>>>> +#define CORE_3_0V_SUPPORT (1 << 25) >>>>>> +#define CORE_1_8V_SUPPORT (1 << 26) >>>>>> + >>>>> >>>>> >>>>> Is there something magical about 25 and 26? This is a new caps field, >>>>> so I'd have expected 0 and 1. >>>>> >>>>> >>> >>> Yes, these bits are the same corresponding to the capabilities in the >>> Capabilities Register (offset 0x40). The bit positions become >>> important when >>> capabilities register doesn't show support to some voltages, but we can >>> support those voltages. At that time, we will have to fake >>> capabilities. The >>> changes for those are currently not yet pushed up. >>> >>> >>>>>> #define CORE_CSR_CDC_CTLR_CFG0 0x130 >>>>>> #define CORE_SW_TRIG_FULL_CALIB BIT(16) >>>>>> #define CORE_HW_AUTOCAL_ENA BIT(17) >>>>>> @@ -148,6 +152,7 @@ struct sdhci_msm_host { >>>>>> u32 curr_io_level; >>>>>> wait_queue_head_t pwr_irq_wait; >>>>>> bool pwr_irq_flag; >>>>>> + u32 caps_0; >>>>>> }; >>>>>> >>>>>> static unsigned int msm_get_clock_rate_for_bus_mode(struct >>>>>> sdhci_host >>>>>> *host, >>>>>> @@ -1313,6 +1318,35 @@ static void sdhci_msm_writeb(struct sdhci_host >>>>>> *host, u8 val, int reg) >>>>>> sdhci_msm_check_power_status(host, req_type); >>>>>> } >>>>>> >>>>>> +static int sdhci_msm_set_regulator_caps(struct sdhci_msm_host >>>>>> *msm_host) >>>>>> +{ >>>>>> + struct mmc_host *mmc = msm_host->mmc; >>>>>> + struct regulator *supply = mmc->supply.vqmmc; >>>>>> + int i, count; >>>>>> + u32 caps = 0, vdd_uV; >>>>>> + >>>>>> + if (!IS_ERR(mmc->supply.vqmmc)) { >>>>>> + count = regulator_count_voltages(supply); >>>>>> + if (count < 0) >>>>>> + return count; >>>>>> + for (i = 0; i < count; i++) { >>>>>> + vdd_uV = regulator_list_voltage(supply, i); >>>>>> + if (vdd_uV <= 0) >>>>>> + continue; >>>>>> + if (vdd_uV > 2700000) >>>>>> + caps |= CORE_3_0V_SUPPORT; >>>>>> + if (vdd_uV < 1950000) >>>>>> + caps |= CORE_1_8V_SUPPORT; >>>>>> + } >>>>> >>>>> >>>>> Shouldn't you be using regulator_is_supported_voltage() rather than >>>>> open coding? Also: I've never personally worked on a device where it >>>>> was used, but there is definitely a concept floating about of a >>>>> voltage level of 1.2V. Maybe should copy the ranges from >>>>> mmc_regulator_set_vqmmc()? >>>>> >>>>> >>> >>> regulator_is_supported_voltage() checks for a range and it also uses >>> regulator_list_voltage() internally. regulator_list_voltage() is also an >>> exported API for use by drivers AFAIK. Please correct if it is not. >> >> Sure, regulator_list_voltage() is valid to call. I'm not saying that >> your code is wrong or violates abstractions, just that it's >> essentially re-implementing regulator_is_supported_voltage() for very >> little gain. Calling regulator_is_supported_voltage() is better >> because: >> >> 1. In theory, it should generate less code. Sure, it might loop twice >> with the current implementation of regulator_is_supported_voltage(), >> but for a non-time-critical section like this smaller code is likely >> better than faster code (decreases kernel size / uses up less cache >> space, etc). >> >> 2. If regulator_is_supported_voltage() is ever improved to be more >> efficient you'll get that improvement automatically. If someone >> happened to source vqmmc from a PWM regulator, for instance, trying to >> enumerate all voltages like this would be a disaster. >> >> 3. Code will be simpler to understand. >> >> You can replace your whole loop with: >> >> if (regulator_is_supported_voltage(mmc->supply.vqmmc, 1700000, 1950000)) >> caps |= CORE_1_8V_SUPPORT >> if (regulator_is_supported_voltage(mmc->supply.vqmmc, 2700000, 3600000)) >> caps |= CORE_3_0V_SUPPORT >> >> >>>>> Also: seems like you should have some way to deal with "caps" ending >>>>> up w/ no bits set. IIRC you can have a regulator that can be enabled >>>>> / disabled but doesn't list a voltage, so if someone messed up their >>>>> device tree you could end up in this case. Should you print a >>>>> warning? ...or treat it as if we support "3.0V"? ...or ? I guess it >>>>> depends on how do you want patch #2 to behave in that case. >>>> >>>> >>>> Both, initialize it to sane value and print something. This way at >>>> least you have a good chance of booting and not hard hanging and you >>>> are given a reasonable message indicating what needs to be fixed. >>>> >>>> -jeremy >>>> > > Its good to add a warning, but initializing it to some value might not > be appropriate. It will be better to leave it blank and if caps doesn't > have any of 1.8V/3V, better to not enable IO_PAD_PWR_SWITCH_EN. >
That makes sense, this way if someone messes up their dts they will at least get a message and we won't set the voltage to something that could potentially destroy / harm the hardware.
-jeremy
>>>>> >>>>> >>>>>> + } >>>>> >>>>> >>>>> How should things behave if vqmmc is an error? In that case is it >>>>> important to not set "CORE_IO_PAD_PWR_SWITCH_EN" in patch set #2? >>>>> ...or should you set "CORE_IO_PAD_PWR_SWITCH_EN" but then make sure >>>>> you don't set "CORE_IO_PAD_PWR_SWITCH"? >>>>> >>>>> >>> >>> Thanks for the suggestion. If the regulators exit and doesn't list the >>> voltages, then I believe initialization itself will not happen. We >>> will not >>> have any available ocr and in sdhci_setup_host it should fail. >>> But these enhancements can be incorporated. Since this patch is already >>> acknowledged, I will incorporate these changes in a subsequent patch. >> >> It's already acknowledged? I saw that your RFC was acknowledged by >> Adrian Hunter but then you didn't include that tag in the posting of >> v2, so I assumed for some reason it no longer applied. If you're >> thinking that Ulf would be the one to apply this patch, he probably >> doesn't know that it's Acked either. >> >> Perhaps Adrian or Ulf can give direction for how they see this patch >> proceeding. >> >> > > Since I put up V2 anyway, I will include your suggestions and put V3. My > mistake, I didn't notice the ACK was for RFC. > >>>>>> + msm_host->caps_0 |= caps; >>>>>> + pr_debug("%s: %s: supported caps: 0x%08x\n", >>>>>> mmc_hostname(mmc), >>>>>> + __func__, caps); >>>>>> + >>>>>> + return 0; >>>>>> +} >>>>>> + >>>>>> + >>>>>> static const struct of_device_id sdhci_msm_dt_match[] = { >>>>>> { .compatible = "qcom,sdhci-msm-v4" }, >>>>>> {}, >>>>>> @@ -1530,6 +1564,10 @@ static int sdhci_msm_probe(struct >>>>>> platform_device >>>>>> *pdev) >>>>>> ret = sdhci_add_host(host); >>>>>> if (ret) >>>>>> goto pm_runtime_disable; >>>>>> + ret = sdhci_msm_set_regulator_caps(msm_host); >>>>>> + if (ret) >>>>>> + dev_err(&pdev->dev, "%s: Failed to set regulator >>>>>> caps: >>>>>> %d\n", >>>>>> + __func__, ret); >>>>> >>>>> >>>>> Why do you need __func__ here? You're already using dev_err(), that >>>>> gives an idea of where we are. >>>>> >>> >>> dev_err() doesn't give information of where it is getting called. >> >> It gives you the driver and the error message should be unique to the >> driver and easy to find. Including "__func__ in messages like this is >> discouraged unless you are in a context where you somehow can't get >> access to the device pointer. I suppose ultimately it's up the the >> maintainer for individual cases but overall I've seen this to be a >> consistently applied rule in the kernel. >> >> In any case, why would this particular print be special that it should >> include __func__ but all others (in this file, or in dev_err in >> general) shouldn't? >> >> >>>>>> pm_runtime_mark_last_busy(&pdev->dev); >>>>>> pm_runtime_put_autosuspend(&pdev->dev); >>>>>> -- >>>>>> Qualcomm India Private Limited, on behalf of Qualcomm Innovation >>>>>> Center, Inc. >>>>>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a >>>>>> Linux Foundation Collaborative Project. >>>>>> >>>>>> -- >>>>>> To unsubscribe from this list: send the line "unsubscribe >>>>>> linux-mmc" in >>>>>> the body of a message to majordomo@vger.kernel.org >>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> >>>> >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in >>>> the body of a message to majordomo@vger.kernel.org >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >>> >>> Thanks, >>> Vijay >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > Thanks, > Vijay > -- > To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
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