1 files changed, 57 insertions, 14 deletions

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 7817cef6aae1..1f27b350ae01 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -122,6 +122,11 @@ enum {
         TP_NVRAM_POS_LEVEL_VOLUME       = 0,
 };
 
+/* Misc NVRAM-related */
+enum {
+        TP_NVRAM_LEVEL_VOLUME_MAX = 14,
+};
+
 /* ACPI HIDs */
 #define TPACPI_ACPI_HKEY_HID            "IBM0068"
 
@@ -2418,6 +2423,21 @@ static void hotkey_compare_and_issue_event(struct tp_nvram_state *oldn,
                         tpacpi_hotkey_send_key(__scancode); \
         } while (0)
 
+        void issue_volchange(const unsigned int oldvol,
+                             const unsigned int newvol)
+        {
+                unsigned int i = oldvol;
+
+                while (i > newvol) {
+                        TPACPI_MAY_SEND_KEY(TP_ACPI_HOTKEYSCAN_VOLUMEDOWN);
+                        i--;
+                }
+                while (i < newvol) {
+                        TPACPI_MAY_SEND_KEY(TP_ACPI_HOTKEYSCAN_VOLUMEUP);
+                        i++;
+                }
+        }
+
         TPACPI_COMPARE_KEY(TP_ACPI_HOTKEYSCAN_THINKPAD, thinkpad_toggle);
         TPACPI_COMPARE_KEY(TP_ACPI_HOTKEYSCAN_FNSPACE, zoom_toggle);
         TPACPI_COMPARE_KEY(TP_ACPI_HOTKEYSCAN_FNF7, display_toggle);
@@ -2427,24 +2447,47 @@ static void hotkey_compare_and_issue_event(struct tp_nvram_state *oldn,
 
         TPACPI_COMPARE_KEY(TP_ACPI_HOTKEYSCAN_FNF8, displayexp_toggle);
 
-        /* handle volume */
-        if (oldn->volume_toggle != newn->volume_toggle) {
-                if (oldn->mute != newn->mute) {
+        /*
+         * Handle volume
+         *
+         * This code is supposed to duplicate the IBM firmware behaviour:
+         * - Pressing MUTE issues mute hotkey message, even when already mute
+         * - Pressing Volume up/down issues volume up/down hotkey messages,
+         *   even when already at maximum or minumum volume
+         * - The act of unmuting issues volume up/down notification,
+         *   depending which key was used to unmute
+         *
+         * We are constrained to what the NVRAM can tell us, which is not much
+         * and certainly not enough if more than one volume hotkey was pressed
+         * since the last poll cycle.
+         *
+         * Just to make our life interesting, some newer Lenovo ThinkPads have
+         * bugs in the BIOS and may fail to update volume_toggle properly.
+         */
+        if (newn->mute) {
+                /* muted */
+                if (!oldn->mute ||
+                    oldn->volume_toggle != newn->volume_toggle ||
+                    oldn->volume_level != newn->volume_level) {
+                        /* recently muted, or repeated mute keypress, or
+                         * multiple presses ending in mute */
+                        issue_volchange(oldn->volume_level, newn->volume_level);
                         TPACPI_MAY_SEND_KEY(TP_ACPI_HOTKEYSCAN_MUTE);
                 }
-                if (oldn->volume_level > newn->volume_level) {
-                        TPACPI_MAY_SEND_KEY(TP_ACPI_HOTKEYSCAN_VOLUMEDOWN);
-                } else if (oldn->volume_level < newn->volume_level) {
+        } else {
+                /* unmute */
+                if (oldn->mute) {
+                        /* recently unmuted, issue 'unmute' keypress */
                         TPACPI_MAY_SEND_KEY(TP_ACPI_HOTKEYSCAN_VOLUMEUP);
-                } else if (oldn->mute == newn->mute) {
-                        /* repeated key presses that didn't change state */
-                        if (newn->mute) {
-                                TPACPI_MAY_SEND_KEY(TP_ACPI_HOTKEYSCAN_MUTE);
-                        } else if (newn->volume_level != 0) {
-                                TPACPI_MAY_SEND_KEY(TP_ACPI_HOTKEYSCAN_VOLUMEUP);
-                        } else {
+                }
+                if (oldn->volume_level != newn->volume_level) {
+                        issue_volchange(oldn->volume_level, newn->volume_level);
+                } else if (oldn->volume_toggle != newn->volume_toggle) {
+                        /* repeated vol up/down keypress at end of scale ? */
+                        if (newn->volume_level == 0)
                                 TPACPI_MAY_SEND_KEY(TP_ACPI_HOTKEYSCAN_VOLUMEDOWN);
-                        }
+                        else if (newn->volume_level >= TP_NVRAM_LEVEL_VOLUME_MAX)
+                                TPACPI_MAY_SEND_KEY(TP_ACPI_HOTKEYSCAN_VOLUMEUP);
                 }
         }