mfd: db8500-prcmu tweak for modem wakeup

This is a tweak for the case where the modem goes to sleep while
emitting the AC_WAKE_ACK anyway. Also print the modem errors as
critical, since they jeopardize the entire platform when they
occur.

Signed-off-by: Mattias Nilsson <mattias.i.nilsson@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 28 insertions, 4 deletions

diff --git a/drivers/mfd/db8500-prcmu.c b/drivers/mfd/db8500-prcmu.c
index 95498f80c905..cb58e44b1e45 100644
--- a/drivers/mfd/db8500-prcmu.c
+++ b/drivers/mfd/db8500-prcmu.c
@@ -1745,6 +1745,7 @@ int prcmu_abb_write(u8 slave, u8 reg, u8 *value, u8 size)
 void prcmu_ac_wake_req(void)
 {
         u32 val;
+        u32 status;
 
         mutex_lock(&mb0_transfer.ac_wake_lock);
 
@@ -1754,11 +1755,34 @@ void prcmu_ac_wake_req(void)
 
         atomic_set(&ac_wake_req_state, 1);
 
+retry:
         writel((val | PRCM_HOSTACCESS_REQ_HOSTACCESS_REQ), PRCM_HOSTACCESS_REQ);
 
         if (!wait_for_completion_timeout(&mb0_transfer.ac_wake_work,
-                        msecs_to_jiffies(20000))) {
-                pr_err("prcmu: %s timed out (20 s) waiting for a reply.\n",
+                        msecs_to_jiffies(5000))) {
+                panic("prcmu: %s timed out (5 s) waiting for a reply.\n",
+                        __func__);
+                goto unlock_and_return;
+        }
+
+        /*
+         * The modem can generate an AC_WAKE_ACK, and then still go to sleep.
+         * As a workaround, we wait, and then check that the modem is indeed
+         * awake (in terms of the value of the PRCM_MOD_AWAKE_STATUS
+         * register, which may not be the whole truth).
+         */
+        udelay(400);
+        status = (readl(PRCM_MOD_AWAKE_STATUS) & BITS(0, 2));
+        if (status != (PRCM_MOD_AWAKE_STATUS_PRCM_MOD_AAPD_AWAKE |
+                        PRCM_MOD_AWAKE_STATUS_PRCM_MOD_COREPD_AWAKE)) {
+                pr_err("prcmu: %s received ack, but modem not awake (0x%X).\n",
+                        __func__, status);
+                udelay(1200);
+                writel(val, PRCM_HOSTACCESS_REQ);
+                if (wait_for_completion_timeout(&mb0_transfer.ac_wake_work,
+                                msecs_to_jiffies(5000)))
+                        goto retry;
+                panic("prcmu: %s timed out (5 s) waiting for AC_SLEEP_ACK.\n",
                         __func__);
         }
 
@@ -1783,8 +1807,8 @@ void prcmu_ac_sleep_req()
                 PRCM_HOSTACCESS_REQ);
 
         if (!wait_for_completion_timeout(&mb0_transfer.ac_wake_work,
-                        msecs_to_jiffies(20000))) {
-                pr_err("prcmu: %s timed out (20 s) waiting for a reply.\n",
+                        msecs_to_jiffies(5000))) {
+                panic("prcmu: %s timed out (5 s) waiting for a reply.\n",
                         __func__);
         }