linux-kernel - Re: [PATCH 12/12] extcon: axp288: Set USB role where necessary

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Date:   Sun, 25 Feb 2018 14:49:59 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        USB <linux-usb@...r.kernel.org>
Subject: Re: [PATCH 12/12] extcon: axp288: Set USB role where necessary

Hi,

On 16-02-18 14:19, Andy Shevchenko wrote:
> On Fri, Feb 16, 2018 at 12:47 PM, Hans de Goede <hdegoede@...hat.com> wrote:
>> The AXP288 BC1.2 charger detection / extcon code may seem like a strange
>> place to add code to control the USB role-switch on devices with an AXP288,
>> but there are 2 reasons to do this inside the axp288 extcon code:
>>
>> 1) On many devices the USB role is controlled by ACPI AML code, but the AML
>>     code only switches between the host and none roles, because of Windows
>>     not really using device mode. To make device mode work we need to toggle
>>     between the none/device roles based on VBus presence, and the axp288
>>     extcon gets interrupts on VBus insertion / removal.
>>
>> 2) In order for our BC1.2 charger detection to work properly the role
>>     mux must be properly set to device mode before we do the detection.
>>
>> Also note the Kconfig help-text / obsolete depends on USB_PHY which are
>> remnants from older never upstreamed code also controlling the mux from
>> the axp288 extcon code.
>>
>> This commit also adds code to get notifications from the INT3496 extcon
>> device, which is used on some devices to notify the kernel about id-pin
>> changes instead of them being handled through AML code.
>>
>> This fixes:
>> -Device mode not working on most CHT devices with an AXP288
>> -Host mode not working on devices with an INT3496 ACPI device
>> -Charger-type misdetection (always SDP) on devices with an INT3496 when the
>>   USB role (always) gets initialized as host
>>
>> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> 
>>   config EXTCON_AXP288
>>          tristate "X-Power AXP288 EXTCON support"
>> -       depends on MFD_AXP20X && USB_PHY
>> +       depends on MFD_AXP20X && USB_SUPPORT
>> +       select USB_ROLE_SWITCH
> 
> Is it supposed to work outside of x86 world?..

No.

>> +#include <asm/cpu_device_id.h>
>> +#include <asm/intel-family.h>
> 
> ...if yes, this should go under CONFIG_X86 along with accompanying parts.
> 
> ...if no, put corresponding dependency to Kconfig.

Ack, added the dependency for v2 of the patch-set.

>> +       if (info->role_sw) {
>> +               ret = devm_add_action_or_reset(dev, axp288_put_role_sw, info);
>> +               if (ret)
>> +                       return ret;
>> +
>> +               if (acpi_dev_present("INT3496", NULL, -1)) {
>> +                       info->id_extcon = extcon_get_extcon_dev("INT3496:00");
> 
> Please use instance found by acpi_dev_present(). Okay, actually new
> helper is here:
> acpi_dev_get_first_match_name().

Good call, I've switched to acpi_dev_get_first_match_name() for v2.


> 
>> +                       if (!info->id_extcon)
>> +                               return -EPROBE_DEFER;
>> +
>> +                       dev_info(dev, "controlling USB role\n");
>> +               } else {
>> +                       dev_info(dev, "controlling USB role based on vbus presence\n");
>> +               }
>> +       }
>> +
> 

Andy, Thank you for all the reviews!

Regards,

Hans