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Date: Mon, 12 Nov 2018 22:49:36 +0530
From: Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
To: Evan Green <evgreen@...omium.org>
Cc: adrian.hunter@...el.com, Ulf Hansson <ulf.hansson@...aro.org>,
robh+dt@...nel.org, Doug Anderson <dianders@...gle.com>,
asutoshd@...eaurora.org, riteshh@...eaurora.org,
stummala@...eaurora.org, sayali <sayalil@...eaurora.org>,
linux-mmc@...r.kernel.org, linux-arm-msm@...r.kernel.org,
vviswana@...eaurora.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 1/3] mmc: sdhci: Allow platform controlled voltage
switching
On 10/17/2018 3:39 AM, Evan Green wrote:
> On Mon, Oct 8, 2018 at 6:22 AM Veerabhadrarao Badiganti
> <vbadigan@...eaurora.org> wrote:
>> From: Vijay Viswanath <vviswana@...eaurora.org>
>>
>> Some controllers can have internal mechanism to inform the SW that it
>> is ready for voltage switching. For such controllers, changing voltage
>> before the HW is ready can result in various issues.
>>
>> During setup/cleanup of host, check whether regulator enable/disable
>> was already done by platform driver.
>>
>> Signed-off-by: Vijay Viswanath <vviswana@...eaurora.org>
>> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
>> ---
>> drivers/mmc/host/sdhci.c | 32 +++++++++++++++++++-------------
>> drivers/mmc/host/sdhci.h | 1 +
>> 2 files changed, 20 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index 99bdae5..ea7ce1d 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -3616,6 +3616,7 @@ int sdhci_setup_host(struct sdhci_host *host)
>> unsigned int override_timeout_clk;
>> u32 max_clk;
>> int ret;
>> + bool enable_vqmmc = false;
>>
>> WARN_ON(host == NULL);
>> if (host == NULL)
>> @@ -3629,9 +3630,12 @@ int sdhci_setup_host(struct sdhci_host *host)
>> * the host can take the appropriate action if regulators are not
>> * available.
>> */
>> - ret = mmc_regulator_get_supply(mmc);
>> - if (ret)
>> - return ret;
>> + if (!mmc->supply.vqmmc) {
>> + ret = mmc_regulator_get_supply(mmc);
>> + if (ret)
>> + return ret;
>> + enable_vqmmc = true;
>> + }
> Did you not like my suggestion in the previous patch of changing
> mmc_regulator_get_supply to only get supplies that were not set
> previously? What you have here is almost the same, except you've got
> this weird coupling where if vqmmc is already present, you implicitly
> skip looking at vmmc entirely (since mmc_regulator_get_supply does
> more than just get vqmmc).
sure. Will update mmc_regulator_get_supply() as you suggested.
>> DBG("Version: 0x%08x | Present: 0x%08x\n",
>> sdhci_readw(host, SDHCI_HOST_VERSION),
>> @@ -3880,7 +3884,15 @@ int sdhci_setup_host(struct sdhci_host *host)
>> mmc->caps |= MMC_CAP_NEEDS_POLL;
>>
>> if (!IS_ERR(mmc->supply.vqmmc)) {
>> - ret = regulator_enable(mmc->supply.vqmmc);
>> + if (enable_vqmmc) {
>> + ret = regulator_enable(mmc->supply.vqmmc);
>> + if (ret) {
>> + pr_warn("%s: Failed to enable vqmmc regulator: %d\n",
>> + mmc_hostname(mmc), ret);
>> + mmc->supply.vqmmc = ERR_PTR(-EINVAL);
>> + }
>> + host->vqmmc_enabled = !ret;
>> + }
>>
>> /* If vqmmc provides no 1.8V signalling, then there's no UHS */
>> if (!regulator_is_supported_voltage(mmc->supply.vqmmc, 1700000,
>> @@ -3893,12 +3905,6 @@ int sdhci_setup_host(struct sdhci_host *host)
>> if (!regulator_is_supported_voltage(mmc->supply.vqmmc, 2700000,
>> 3600000))
>> host->flags &= ~SDHCI_SIGNALING_330;
>> -
>> - if (ret) {
>> - pr_warn("%s: Failed to enable vqmmc regulator: %d\n",
>> - mmc_hostname(mmc), ret);
>> - mmc->supply.vqmmc = ERR_PTR(-EINVAL);
>> - }
>> }
>>
>> if (host->quirks2 & SDHCI_QUIRK2_NO_1_8_V) {
>> @@ -4136,7 +4142,7 @@ int sdhci_setup_host(struct sdhci_host *host)
>> return 0;
>>
>> unreg:
>> - if (!IS_ERR(mmc->supply.vqmmc))
>> + if (host->vqmmc_enabled)
>> regulator_disable(mmc->supply.vqmmc);
>> undma:
>> if (host->align_buffer)
>> @@ -4154,7 +4160,7 @@ void sdhci_cleanup_host(struct sdhci_host *host)
>> {
>> struct mmc_host *mmc = host->mmc;
>>
>> - if (!IS_ERR(mmc->supply.vqmmc))
>> + if (host->vqmmc_enabled)
>> regulator_disable(mmc->supply.vqmmc);
>>
>> if (host->align_buffer)
>> @@ -4287,7 +4293,7 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
>>
>> tasklet_kill(&host->finish_tasklet);
>>
>> - if (!IS_ERR(mmc->supply.vqmmc))
>> + if (host->vqmmc_enabled)
>> regulator_disable(mmc->supply.vqmmc);
>>
>> if (host->align_buffer)
>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>> index b001cf4..3c28152 100644
>> --- a/drivers/mmc/host/sdhci.h
>> +++ b/drivers/mmc/host/sdhci.h
>> @@ -524,6 +524,7 @@ struct sdhci_host {
>> bool pending_reset; /* Cmd/data reset is pending */
>> bool irq_wake_enabled; /* IRQ wakeup is enabled */
>> bool v4_mode; /* Host Version 4 Enable */
>> + bool vqmmc_enabled; /* Vqmmc is enabled */
> I still don't love this, since it doesn't mean what it says. Everyone
> else that has a vqmmc_enabled member uses it to actually mean "vqmmc
> is enabled", but this doesn't mean that. For example, you don't clear
> this when you disable the regulator in patch 3, so this would be set
> even if the regulator is disabled, and you don't set it when sdhci
> enables the regulator, so the regulator is on when this flag is not
> set.
>
> At the very least, I think a rename is in order. I'm struggling with
> the rename, since
> "vqmmc_pltfrm_enable_but_feel_free_to_call_set_voltage_anywhere" is
> too long. I guess vqmmc_pltfrm_enabled is the best I've got for now.
Sure. Will rename it.
>> struct mmc_request *mrqs_done[SDHCI_MAX_MRQS]; /* Requests done */
>> struct mmc_command *cmd; /* Current command */
>> --
>> 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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