| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <0d9b1934-d80d-a726-8094-688c97474afa@codeaurora.org>
Date: Tue, 17 Jul 2018 10:44:49 +0530
From: Vijay Viswanath <vviswana@...eaurora.org>
To: Adrian Hunter <adrian.hunter@...el.com>, ulf.hansson@...aro.org,
robh+dt@...nel.org, mark.rutland@....com
Cc: linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
shawn.lin@...k-chips.com, linux-arm-msm@...r.kernel.org,
georgi.djakov@...aro.org, devicetree@...r.kernel.org,
asutoshd@...eaurora.org, stummala@...eaurora.org,
venkatg@...eaurora.org, jeremymc@...hat.com,
bjorn.andersson@...aro.org, riteshh@...eaurora.org,
vbadigan@...eaurora.org, dianders@...gle.com,
sayalil@...eaurora.org, Evan Green <evgreen@...omium.org>
Subject: Re: [PATCH RFC 1/2] mmc: sdhci: Allow platform controlled voltage
switching
On 7/10/2018 4:37 PM, Adrian Hunter wrote:
> On 21/06/18 15:23, Vijay Viswanath wrote:
>> 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.
>>
>> Add a quirk, which can be used by drivers of such controllers.
>>
>> Signed-off-by: Vijay Viswanath <vviswana@...eaurora.org>
>> ---
>> drivers/mmc/host/sdhci.c | 20 +++++++++++++++-----
>> drivers/mmc/host/sdhci.h | 2 ++
>> 2 files changed, 17 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index 1c828e0..f0346d4 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -1615,7 +1615,8 @@ void sdhci_set_power_noreg(struct sdhci_host *host, unsigned char mode,
>> void sdhci_set_power(struct sdhci_host *host, unsigned char mode,
>> unsigned short vdd)
>> {
>> - if (IS_ERR(host->mmc->supply.vmmc))
>> + if (IS_ERR(host->mmc->supply.vmmc) ||
>> + (host->quirks2 & SDHCI_QUIRK2_INTERNAL_PWR_CTL))
>
> I think you should provide your own ->set_power() instead of this
>
will do
>> sdhci_set_power_noreg(host, mode, vdd);
>> else
>> sdhci_set_power_reg(host, mode, vdd);
>> @@ -2009,7 +2010,9 @@ int sdhci_start_signal_voltage_switch(struct mmc_host *mmc,
>> ctrl &= ~SDHCI_CTRL_VDD_180;
>> sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
>>
>> - if (!IS_ERR(mmc->supply.vqmmc)) {
>> + if (!IS_ERR(mmc->supply.vqmmc) &&
>> + !(host->quirks2 &
>> + SDHCI_QUIRK2_INTERNAL_PWR_CTL)) {
>
> And your own ->start_signal_voltage_switch()
>
sdhci_msm_start_signal_voltage_switch() would be an exact copy of
sdhci_start_signal_voltage_switch()..... will incorporate this if not
using quirk.
>> ret = mmc_regulator_set_vqmmc(mmc, ios);
>> if (ret) {
>> pr_warn("%s: Switching to 3.3V signalling voltage failed\n",
>> @@ -2032,7 +2035,8 @@ int sdhci_start_signal_voltage_switch(struct mmc_host *mmc,
>> case MMC_SIGNAL_VOLTAGE_180:
>> if (!(host->flags & SDHCI_SIGNALING_180))
>> return -EINVAL;
>> - if (!IS_ERR(mmc->supply.vqmmc)) {
>> + if (!IS_ERR(mmc->supply.vqmmc) &&
>> + !(host->quirks2 & SDHCI_QUIRK2_INTERNAL_PWR_CTL)) {
>> ret = mmc_regulator_set_vqmmc(mmc, ios);
>> if (ret) {
>> pr_warn("%s: Switching to 1.8V signalling voltage failed\n",
>> @@ -3485,7 +3489,10 @@ 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 (!(host->quirks2 & SDHCI_QUIRK2_INTERNAL_PWR_CTL))
>
> Since we expect mmc_regulator_get_supply() to have been called, this could be:
>
> if (!mmc->supply.vmmc) {
> ret = mmc_regulator_get_supply(mmc);
> enable_vqmmc = true;
> } else {
> ret = 0;
> }
> >> + ret = mmc_regulator_get_supply(mmc);
>> + else
>> + ret = 0;
>> if (ret)
>> return ret;
>>
>> @@ -3736,7 +3743,10 @@ int sdhci_setup_host(struct sdhci_host *host)
>>
>> /* If vqmmc regulator and no 1.8V signalling, then there's no UHS */
>> if (!IS_ERR(mmc->supply.vqmmc)) {
>> - ret = regulator_enable(mmc->supply.vqmmc);
>> + if (!(host->quirks2 & SDHCI_QUIRK2_INTERNAL_PWR_CTL))
>
> And this could be:
>
> if (enable_vqmmc)
> ret = regulator_enable(mmc->supply.vqmmc);
> else
> ret = 0;
> > However, you still need to ensure regulator_disable(mmc->supply.vqmmc) is
> only called if regulator_enable() was called.
I missed this. Will cover it.
Also I missed one more place where we are doing regulator_disable.
During sdhci-msm unbinding, we would end up doing an extra regulator
disable (thanks Evan for pointing it out) in sdhci_remove_host.
To avoid the quirk( or having any flag), it would require copying the
code of sdhci_start_signal_voltage_switch() and sdhci_remove_host() and
creating 2 new functions in sdhci_msm layer which would do the exact
same as above, with just the regulator parts removed.
This looks messy (considering any future changes to the 2 sdhci API will
need to be copied to their duplicate sdhci_msm API) and a bit overkill
to avoid quirk. At the same time, I don't know how useful such a quirk
would be to other platform drivers.
Please let me know your view/suggestions.
>
>> + ret = regulator_enable(mmc->supply.vqmmc);
>> + else
>> + ret = 0;
>> if (!regulator_is_supported_voltage(mmc->supply.vqmmc, 1700000,
>> 1950000))
>> host->caps1 &= ~(SDHCI_SUPPORT_SDR104 |
>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>> index 23966f8..3b0c97a 100644
>> --- a/drivers/mmc/host/sdhci.h
>> +++ b/drivers/mmc/host/sdhci.h
>> @@ -450,6 +450,8 @@ struct sdhci_host {
>> * obtainable timeout.
>> */
>> #define SDHCI_QUIRK2_DISABLE_HW_TIMEOUT (1<<17)
>> +/* Regulator voltage changes are being done from platform layer */
>> +#define SDHCI_QUIRK2_INTERNAL_PWR_CTL (1<<18)
>
> So maybe the quirk is not needed.
>
>>
>> int irq; /* Device IRQ */
>> void __iomem *ioaddr; /* Mapped address */
>>
>
Thanks for the review & suggestions!
Vijay
Powered by blists - more mailing lists