Historically, 21UX2 and 24HD have the select groups inverted
(0 is the right LED bank, and 1 the left one).

This is not right, so fix that in the new LED API. For backward
compatibility, we keep the wacom_led sysfs ABI stable. We don't
need to care about luminance for these two devices as only the
select sysfs file gets exported (brightness is not configurable).

Signed-off-by: Benjamin Tissoires <benjamin.tissoi...@redhat.com>
---
 drivers/hid/wacom_sys.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
index b88896c..153e453 100644
--- a/drivers/hid/wacom_sys.c
+++ b/drivers/hid/wacom_sys.c
@@ -683,8 +683,10 @@ static int wacom_led_control(struct wacom *wacom)
                int led = wacom->led.groups[0].select | 0x4;
 
                if (wacom->wacom_wac.features.type == WACOM_21UX2 ||
-                   wacom->wacom_wac.features.type == WACOM_24HD)
-                       led |= (wacom->led.groups[1].select << 4) | 0x40;
+                   wacom->wacom_wac.features.type == WACOM_24HD) {
+                       led <<= 4;
+                       led |= wacom->led.groups[1].select | 0x04;
+               }
 
                buf[0] = report_id;
                buf[1] = led;
@@ -742,6 +744,19 @@ out:
        return retval;
 }
 
+static inline int wacom_led_select_get_id(struct wacom *wacom, int set_id)
+{
+       /*
+        * Historically, 21UX2 and 24HD have the select groups inverted
+        * (0 is the right LED bank, and 1 the left one)
+        */
+       if (wacom->wacom_wac.features.type == WACOM_21UX2 ||
+           wacom->wacom_wac.features.type == WACOM_24HD)
+               return 1 - set_id;
+
+       return set_id;
+}
+
 static ssize_t wacom_led_select_store(struct device *dev, int set_id,
                                      const char *buf, size_t count)
 {
@@ -754,6 +769,8 @@ static ssize_t wacom_led_select_store(struct device *dev, 
int set_id,
        if (err)
                return err;
 
+       set_id = wacom_led_select_get_id(wacom, set_id);
+
        mutex_lock(&wacom->lock);
 
        wacom->led.groups[set_id].select = id & 0x3;
@@ -775,8 +792,9 @@ static ssize_t wacom_led##SET_ID##_select_show(struct 
device *dev,  \
 {                                                                      \
        struct hid_device *hdev = to_hid_device(dev);\
        struct wacom *wacom = hid_get_drvdata(hdev);                    \
+       int set_id = wacom_led_select_get_id(wacom, SET_ID);            \
        return scnprintf(buf, PAGE_SIZE, "%d\n",                        \
-                        wacom->led.groups[SET_ID].select);             \
+                        wacom->led.groups[set_id].select);             \
 }                                                                      \
 static DEVICE_ATTR(status_led##SET_ID##_select, DEV_ATTR_RW_PERM,      \
                    wacom_led##SET_ID##_select_show,                    \
-- 
2.5.5

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