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>

diff --git a/drivers/mfd/db8500-prcmu.c b/drivers/mfd/db8500-prcmu.c
index 95498f80c90553cbccad8186405be6c193151e02..cb58e44b1e4560cc0bcdf5c630c86dd02f84cf05 100644 (file)
--- 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__);
        }