Messages in this thread | | | Subject | Re: [PATCH V2 1/3] mmc: sdhci: Allow platform controlled voltage switching | From | Veerabhadrarao Badiganti <> | Date | Thu, 4 Oct 2018 18:16:49 +0530 |
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Hi Evan,
On 9/22/2018 1:38 AM, Evan Green wrote: > On Wed, Sep 19, 2018 at 11:24 PM Veerabhadrarao Badiganti > <vbadigan@codeaurora.org> wrote: >> From: Vijay Viswanath <vviswana@codeaurora.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@codeaurora.org> >> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org> >> --- >> drivers/mmc/host/sdhci.c | 22 +++++++++++++++------- >> drivers/mmc/host/sdhci.h | 1 + >> 2 files changed, 16 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c >> index 99bdae5..04b3fd2 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.vmmc) { >> + ret = mmc_regulator_get_supply(mmc); >> + if (ret) >> + return ret; >> + enable_vqmmc = true; > The coupling of logic strikes me as a little bit odd, it's saying if > vmmc is already present, then don't turn on vqmmc. I guess what it's > trying to say is "hands off all the regulators, I've got this". It > might be cleaner to set enable_vqmmc based on whether or not > mmc->supply.vqmmc exists before the get_supply call, rather than > coupling it into whether or not vmmc exists. > > Actually, what might be even nicer is to change > mmc_regulator_get_supply to only get supplies that it doesn't already > have. You'd still have your enable_vqmmc local, but the > mmc_regulator_get_supply call would be outside the conditional, and > the logic of "don't enable vqmmc if it existed before" would make more > sense.
Yes, its saying if platform driver has already controlling the regulators, don't enable/disable them anymore. Agree with you on the conditional check. Will update it to Vcmmc instead of vmmc.
>> + } >> >> DBG("Version: 0x%08x | Present: 0x%08x\n", >> sdhci_readw(host, SDHCI_HOST_VERSION), >> @@ -3880,7 +3884,11 @@ 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); >> + host->vqmmc_enabled = !ret; >> + } else >> + ret = 0; > I think it's preferred that if your "if" had curly braces, then the > else part needs it too. Actually, can you move the if (ret) pr_warn > stuff up and inside of your if statement above? That keeps the logic > together, and then you don't need an else case at all!
sure. Will update.
>> /* If vqmmc provides no 1.8V signalling, then there's no UHS */ >> if (!regulator_is_supported_voltage(mmc->supply.vqmmc, 1700000, >> @@ -4136,7 +4144,7 @@ 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 +4162,7 @@ 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 +4295,7 @@ 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 */ > This is kind of unpleasant. It's confused by the fact that other host > controllers have a vqmmc_enabled member, but they use it to mean what > it sounds like, "is vqmmc currently enabled". Here you're really using > it to mean "don't ever disable vqmmc in sdhci, because the platform > code sort of owns vqmmc". It only "sort of" owns it in that sdhci is > still free to call regulator_is_supported_voltage and > mmc_regulator_set_vqmmc, but somehow not regulator_disable. Is there > any way to clean up the semantics here?
Except the regualtor_enable()/disable() calls other regulator-operations are direct operations. Only enable() & disable() uses a reference couters to track whether number regualtor_enable() calls matches with number of regualtor_disable() calls or not.
In V1 patch-set this was done without need to this flag but it was suggested have this flag for ensuring enable/disable counters are in sync.
>> 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., is a member of Code Aurora Forum, a Linux Foundation Collaborative Project >>
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