intel_scu_ipc: Drop to C6s0i0 when there is IPC communication ongoing

BZ: 8911

When a IPC command is issued the IPC driver waits for the completion
interrupt from the SCU by issuing a wait_for_competion_timeout API
this causes the IPC driver to sleep, invoking idle process, which then
triggers S0ix, this causes the SCU to disable the interrupts and the
pending IPC completion interrupt is never delivered this causes
IPC timeout to occur.

Fixed this by not doing S0ix by using PM Qos which prevents any deeper
than C6 states from happening. This restrictioin is removed once the
IPC command completes.

Change-Id: I97136b131c1d6019e505e1ab97ec67cec1a473d9
Signed-off-by: Samu Onkalo <samu.onkalo@intel.com>
Signed-off-by: Illyas Mansoor <illyas.mansoor@intel.com>
Signed-off-by: Marie-Celine Dubut <marie.celinex.dubut@intel.com>
Reviewed-on: http://android.intel.com:8080/17210

diff --git a/drivers/platform/x86/intel_scu_ipc.c b/drivers/platform/x86/intel_scu_ipc.c
index 5b22fdd..9367644 100644 (file)
--- a/drivers/platform/x86/intel_scu_ipc.c
+++ b/drivers/platform/x86/intel_scu_ipc.c
@@ -27,6 +27,7 @@
 #include <linux/interrupt.h>
 #include <asm/mrst.h>
 #include <asm/intel_scu_ipc.h>
+#include <linux/pm_qos_params.h>
 
 /*
  * IPC register summary
@@ -90,6 +91,9 @@ static int platform;          /* Platform type */
 
 static DEFINE_MUTEX(ipclock); /* lock used to prevent multiple call to SCU */
 
+/* PM Qos struct */
+static struct pm_qos_request_list *qos;
+
 /*
  * Command Register (Write Only):
  * A write to this register results in an interrupt to the SCU core processor
@@ -106,6 +110,9 @@ static inline void ipc_command(u32 cmd) /* Send ipc command */
                ipcdev.ioc = 0;
                writel(cmd, ipcdev.ipc_base);
        }
+
+       /* Prevent C-states beyond C6 */
+       pm_qos_update_request(qos, 150);
 }
 
 /*
@@ -143,17 +150,20 @@ static inline u32 ipc_data_readl(u32 offset) /* Read ipc u32 data */
 
 static inline int ipc_wait_interrupt(void)
 {
+       int ret = 0;
        if (ipcdev.ioc) {
                if (0 == wait_for_completion_timeout(
                                &ipcdev.cmd_complete, 3 * HZ)) {
                        dev_err(&ipcdev.pdev->dev, "IPC timed out, IPC_STS=0x%x",
                                        ipc_read_status());
-                       return -ETIMEDOUT;
+                       ret = -ETIMEDOUT;
+                       goto leave;
                } else {
                        if ((ipcdev.status >> 1) & 1) {
                                dev_err(&ipcdev.pdev->dev, "IPC failed, IPC_STS=0x%x",
                                                ipc_read_status());
-                               return -EIO;
+                               ret = -EIO;
+                               goto leave;
                        }
                }
        } else {
@@ -167,14 +177,17 @@ static inline int ipc_wait_interrupt(void)
                        loop_count++;
                        if (loop_count > 3000000) {
                                dev_err(&ipcdev.pdev->dev, "IPC timed out");
-                               return -ETIMEDOUT;
+                               ret = -ETIMEDOUT;
+                               goto leave;
                        }
                }
                if ((status >> 1) & 1)
-                       return -EIO;
+                       ret = -EIO;
        }
-
-       return 0;
+leave:
+       /* Re-enable Deeper C-states beyond C6 */
+       pm_qos_update_request(qos, PM_QOS_DEFAULT_VALUE);
+       return ret;
 }
 
 /* Read/Write power control(PMIC in Langwell, MSIC in PenWell) registers */
@@ -1573,11 +1586,18 @@ static int __init intel_scu_ipc_init(void)
        platform = mrst_identify_cpu();
        if (platform == 0)
                return -ENODEV;
+
+       qos = pm_qos_add_request(PM_QOS_CPU_DMA_LATENCY,
+                                       PM_QOS_DEFAULT_VALUE);
+
        return  pci_register_driver(&ipc_driver);
+
 }
 
 static void __exit intel_scu_ipc_exit(void)
 {
+       pm_qos_remove_request(qos);
+
        pci_unregister_driver(&ipc_driver);
 }