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>

diff --git a/drivers/extcon/extcon-intel-cht-wc.c b/drivers/extcon/extcon-intel-cht-wc.c
index cf74acb92fe32b06712e48ff9ecd66766e39d36c..89a6449e3f4acf064739ebeaf0e6ffa9aec2b76d 100644 (file)
--- a/drivers/extcon/extcon-intel-cht-wc.c
+++ b/drivers/extcon/extcon-intel-cht-wc.c
@@ -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;
        }
 }