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Date: Fri, 2 Mar 2018 15:08:21 -0800
From: Jeremy McNicoll <jmcnicol@...hat.com>
To: Doug Anderson <dianders@...omium.org>,
Vijay Viswanath <vviswana@...eaurora.org>
Cc: Adrian Hunter <adrian.hunter@...el.com>,
Ulf Hansson <ulf.hansson@...aro.org>,
linux-mmc@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
Shawn Lin <shawn.lin@...k-chips.com>,
linux-arm-msm@...r.kernel.org, georgi.djakov@...aro.org,
asutoshd@...eaurora.org, stummala@...eaurora.org,
venkatg@...eaurora.org, pramod.gurav@...aro.org,
jeremymc@...hat.com, evgreen@...omium.org
Subject: Re: [PATCH V2 1/2] mmc: sdhci-msm: Add support to store supported
vdd-io voltages
On 2018-03-02 10:23 AM, Doug Anderson wrote:
> Hi,
>
> On Sun, Feb 11, 2018 at 10:01 PM, Vijay Viswanath
> <vviswana@...eaurora.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@...eaurora.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.
>
>
>> #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()?
>
>
> 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
>
>
>> + }
>
> 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"?
>
>
>> + 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.
>
>
>>
>> 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.
>>
>> --
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