Re: [PATCH 1/2] mmc: sdhci-acpi: Disable 1.8V modes on external microSD on Lenovo Miix 320

[Adrian Hunter <adrian.hunter@intel.com>]

On 15/01/20 5:31 pm, Hans de Goede wrote:
> Hi,
> 
> On 15-01-2020 14:48, Adrian Hunter wrote:
>> On 15/01/20 3:31 pm, Hans de Goede wrote:
>>> Hi,
>>>
>>> On 15-01-2020 13:57, Adrian Hunter wrote:
>>>> On 8/01/20 11:39 am, Hans de Goede wrote:
>>>>> Based on a sample of 7 DSDTs from Cherry Trail devices using an AXP288
>>>>> PMIC depending on the design one of 2 possible LDOs on the PMIC is used
>>>>> for the MMC signalling voltage, either DLDO3 or GPIO1LDO (GPIO1 pin in
>>>>> low noise LDO mode).
>>>>>
>>>>> The Lenovo Miix 320-10ICR uses GPIO1LDO in the SHC1 ACPI device's DSM
>>>>> methods to set 3.3 or 1.8 signalling voltage and this appears to work
>>>>> as advertised, so presumably the device is actually using GPIO1LDO for
>>>>> the external microSD signalling voltage.
>>>>>
>>>>> But this device has a bug in the _PS0 method of the SHC1 ACPI device,
>>>>> the DSM remembers the last set signalling voltage and the _PS0 restores
>>>>> this after a (runtime) suspend-resume cycle, but it "restores" the voltage
>>>>> on DLDO3 instead of setting it on GPIO1LDO as the DSM method does. DLDO3
>>>>> is used for the LCD and setting it to 1.8V causes the LCD to go black.
>>>>>
>>>>> This issue can be worked around by setting the SDHCI_QUIRK2_NO_1_8_V
>>>>> quirk on the sdhci_host so that the DSM never gets used to program the
>>>>> signalling voltage to 1.8V.
>>>>
>>>> Could you instead call the 3.3V DSM at runtime suspend time, then the _PS0
>>>> would not "restore" the 1.8V value?  That should allow you to use 1.8V
>>>> UHS-I
>>>> speed modes with SD cards that support them.
>>>
>>> I have considered doing this, but this means reprogramming the signal
>>> voltage to 3.3V at a time when the card does not expect this, is this ok?
>>
>> The host controller does not runtime suspend unless the card is runtime
>> suspended, so the bus power should be off.
>>
>>>
>>> We would then also need to recall the DSM to put the voltage back to 1.8V
>>> from resume.
>>
>> No, the card will be reinitialized at 3.3V and switch back to 1.8V.
>>
>>>               I have a feeling that this is probably what Windows does
>>> (I guess it moves the entire card back to a more safe IOS mode before
>>> suspend), accidentally avoiding the bug.
>>>
>>> I assume you want to only call the DSM to set the voltage to 3.3V on
>>> the affected model, or do you want to do this on all machines ?
>>
>> I would stick with the specific machine for now.
> 
> Ok I will give this a try. Hopefully I can make some time for this the
> coming days.
> 
>>> Adding this does seem to introduce more complexity then simply disabling
>>> 1.8V modes and given that it is just a single model which is affected
>>> I went with the more simple option of just disabling the 1.8V modes.
>>>
>>> Ideally we would not need any quirks, but if we do we should at least
>>> make the work-around as simple as possible. So I've a slight preference
>>> for just sticking with DHCI_QUIRK2_NO_1_8_V ...
>>>
>>> Note that the suspend/resume handling is broken also in the sense that
>>> it does not disable the signal voltage during suspend.
>>
>> The bus power gets switched off if the card is runtime suspended.  The host
>> controller should go to D3cold which means everything off.
> 
> Right, what I mean is that the _PS3 method is broken in that it does
> not turn off the voltage-regulator providing the signal voltage, as
> it does do on other machines with a non buggy implementation.

Is that different to what you would get with Windows?

Also, you could possibly build a custom DSDT and fix the _PS0 and _PS3
yourself.  That requires building it into a custom kernel also though.

> 
>>>>> So far we have mostly been able to avoid using device specific quirks in
>>>>> the sdhci-acpi code, but given that this issue is specific to this one
>>>>> model and we certainly do not want to disable 1.8V modes everywhere I
>>>>> see no other option.
>>>>>
>>>>> This commit adds a new mechanism for setting sdhci-acpi specific quirks
>>>>> and a matching sdhci-acpi.quirks module parameter to make testing quirks /
>>>>> similar issues on other devices easier.
>>>>>
>>>>> The first quirk supported by this mechanism is
>>>>> SDHCI_ACPI_QUIRK_SD_NO_1_8V,
>>>>> which when set causes any slots with the SDHCI_ACPI_SD_CD flag to get the
>>>>> SDHCI_QUIRK2_NO_1_8_V quirk set on their sdhci_host.
>>>>>
>>>>> This commit also adds a DMI table for specifying default quirks for some
>>>>> models and adds an entry for the Lenovo Miix 320-10ICR which enables the
>>>>> SDHCI_QUIRK2_NO_1_8_V by default on this model, fixing the LCD going black
>>>>> when the external microSD slot is used.
>>>>>
>>>>> BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=111294
>>>>> BugLink: https://gitlab.freedesktop.org/drm/intel/issues/355
>>>>> Reported-by: russianneuromancer <russianneuromancer@ya.ru>
>>>>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>>>>> ---
>>>>>    drivers/mmc/host/sdhci-acpi.c | 39 +++++++++++++++++++++++++++++++++++
>>>>>    1 file changed, 39 insertions(+)
>>>>>
>>>>> diff --git a/drivers/mmc/host/sdhci-acpi.c b/drivers/mmc/host/sdhci-acpi.c
>>>>> index 105e73d4a3b9..9f150c73e958 100644
>>>>> --- a/drivers/mmc/host/sdhci-acpi.c
>>>>> +++ b/drivers/mmc/host/sdhci-acpi.c
>>>>> @@ -23,6 +23,7 @@
>>>>>    #include <linux/pm.h>
>>>>>    #include <linux/pm_runtime.h>
>>>>>    #include <linux/delay.h>
>>>>> +#include <linux/dmi.h>
>>>>>      #include <linux/mmc/host.h>
>>>>>    #include <linux/mmc/pm.h>
>>>>> @@ -75,6 +76,14 @@ struct sdhci_acpi_host {
>>>>>        unsigned long            private[0] ____cacheline_aligned;
>>>>>    };
>>>>>    +enum {
>>>>> +    SDHCI_ACPI_QUIRK_SD_NO_1_8V            = BIT(0),
>>>>> +};
>>>>> +
>>>>> +static int quirks = -1;
>>>>> +module_param(quirks, int, 0444);
>>>>> +MODULE_PARM_DESC(quirks, "Override sdhci-acpi specific quirks");
>>>>
>>>> Why is a module parameter needed?
>>>
>>> The module parameter is purely to make testing if the same quirk(s)
>>> help on other devices easier. Like the debug_quirks[2] params in sdhci.c
>>
>> Mmm, but we already have SDHCI_QUIRK2_NO_1_8_V
> 
> True, but this only applies to the sdcard slot and not to the eMMC,
> also you are asking for this to be changed to:
> 
> SDHCI_ACPI_QUIRK_SD_SET_SIGNAL_3_3V_ON_SUSPEND
> 
> Which is not duplicate. Anyways if you dislike the module parameter
> bits I can drop them and make this only available through the DMI quirks.
> 

It isn't dislike, it is whether it will ever be needed.

>>>
>>>>> +
>>>>>    static inline void *sdhci_acpi_priv(struct sdhci_acpi_host *c)
>>>>>    {
>>>>>        return (void *)c->private;
>>>>> @@ -647,6 +656,24 @@ static const struct acpi_device_id
>>>>> sdhci_acpi_ids[] = {
>>>>>    };
>>>>>    MODULE_DEVICE_TABLE(acpi, sdhci_acpi_ids);
>>>>>    +static const struct dmi_system_id sdhci_acpi_quirks[] = {
>>>>> +    {
>>>>> +        /*
>>>>> +         * The Lenovo Miix 320-10ICR has a bug in the _PS0 method of
>>>>> +         * the SHC1 ACPI device, this bug causes it to reprogram the
>>>>> +         * wrong LDO (DLDO3) to 1.8V if 1.8V modes are used and the
>>>>> +         * card is (runtime) suspended + resumed. DLDO3 is used for
>>>>> +         * the LCD and setting it to 1.8V causes the LCD to go black.
>>>>> +         */
>>>>> +        .matches = {
>>>>> +            DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
>>>>> +            DMI_MATCH(DMI_PRODUCT_VERSION, "Lenovo MIIX 320-10ICR"),
>>>>> +        },
>>>>> +        .driver_data = (void *)SDHCI_ACPI_QUIRK_SD_NO_1_8V,
>>>>> +    },
>>>>> +    {} /* Terminating entry */
>>>>> +};
>>>>> +
>>>>>    static const struct sdhci_acpi_slot *sdhci_acpi_get_slot(struct
>>>>> acpi_device *adev)
>>>>>    {
>>>>>        const struct sdhci_acpi_uid_slot *u;
>>>>> @@ -663,6 +690,7 @@ static int sdhci_acpi_probe(struct platform_device
>>>>> *pdev)
>>>>>        struct device *dev = &pdev->dev;
>>>>>        const struct sdhci_acpi_slot *slot;
>>>>>        struct acpi_device *device, *child;
>>>>> +    const struct dmi_system_id *id;
>>>>>        struct sdhci_acpi_host *c;
>>>>>        struct sdhci_host *host;
>>>>>        struct resource *iomem;
>>>>> @@ -670,6 +698,14 @@ static int sdhci_acpi_probe(struct platform_device
>>>>> *pdev)
>>>>>        size_t priv_size;
>>>>>        int err;
>>>>>    +    if (quirks == -1) {
>>>>> +        id = dmi_first_match(sdhci_acpi_quirks);
>>>>> +        if (id)
>>>>> +            quirks = (long)id->driver_data;
>>>>> +        else
>>>>> +            quirks = 0;
>>>>> +    }
>>>>> +
>>>>>        device = ACPI_COMPANION(dev);
>>>>>        if (!device)
>>>>>            return -ENODEV;
>>>>> @@ -759,6 +795,9 @@ static int sdhci_acpi_probe(struct platform_device
>>>>> *pdev)
>>>>>                dev_warn(dev, "failed to setup card detect gpio\n");
>>>>>                c->use_runtime_pm = false;
>>>>>            }
>>>>> +
>>>>> +        if (quirks & SDHCI_ACPI_QUIRK_SD_NO_1_8V)
>>>>> +            host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
>>>>>        }
>>>>>          err = sdhci_setup_host(host);
>>>>>
>>>>
>>>
>>
>