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extcon: intel-cht-wc: Report RID_A for ACA adapters 

Make cht_wc_extcon_get_id() report RID_A for ACA adapters, instead of
reporting ID_FLOAT.

According to the spec. we should read the USB-ID pin ADC value
to determine the resistance of the used pull-down resister and
then return RID_A / RID_B / RID_C based on this. But all "Accessory
Charger Adapter"s (ACAs) which users can actually buy always use
a combination of a charging port with one or more USB-A ports, so
they should always use a resistor indicating RID_A. But the spec
is hard to read / badly-worded so some of them actually indicate
they are a RID_B ACA even though they clearly are a RID_A ACA.

To workaround this simply always return INTEL_USB_RID_A, which
matches all the ACAs which users can actually buy.

Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
This commit is contained in:
Hans de Goede 2022-02-01 14:07:06 +01:00 committed by Sebastian Reichel
parent 66e31186cd
commit 21356ac14e
1 changed files with 13 additions and 5 deletions
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18
drivers/extcon/extcon-intel-cht-wc.c
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@ -121,13 +121,21 @@ static int cht_wc_extcon_get_id(struct cht_wc_extcon_data *ext, int pwrsrc_sts)
return INTEL_USB_ID_GND;
case CHT_WC_PWRSRC_RID_FLOAT:
return INTEL_USB_ID_FLOAT;
/*
* According to the spec. we should read the USB-ID pin ADC value here
* to determine the resistance of the used pull-down resister and then
* return RID_A / RID_B / RID_C based on this. But all "Accessory
* Charger Adapter"s (ACAs) which users can actually buy always use
* a combination of a charging port with one or more USB-A ports, so
* they should always use a resistor indicating RID_A. But the spec
* is hard to read / badly-worded so some of them actually indicate
* they are a RID_B ACA evnen though they clearly are a RID_A ACA.
* To workaround this simply always return INTEL_USB_RID_A, which
* matches all the ACAs which users can actually buy.
*/
case CHT_WC_PWRSRC_RID_ACA:
return INTEL_USB_RID_A;
default:
/*
* Once we have IIO support for the GPADC we should read
* the USBID GPADC channel here and determine ACA role
* based on that.
*/
return INTEL_USB_ID_FLOAT;
}
}