ENGR00306397 [#1118] use BUG_ON to check if GPU clock is off

Access GPU register will cause system hang(bus lock-up) without log when clock is off,
GPU kernel BUG_ON is added to check if GPU clock is off when read & write GPU registers,

GPU clock issue can be easily identified with the detailed kernel panic log as below:

kernel BUG at drivers/mxc/gpu-viv/hal/os/linux/kernel/gc_hal_kernel_os.c:2423!
Unable to handle kernel NULL pointer dereference at virtual address 0000000
...
[<c0050008>] (__bug+0x1c/0x28) from [<c046bb3c>] (gckOS_ReadRegisterEx+0xbc/0xdc)
[<c046bb3c>] (gckOS_ReadRegisterEx+0xbc/0xdc) from [<c047eab4>] (gckHARDWARE_QueryIdle+0x4c/0xbc)
[<c047eab4>] (gckHARDWARE_QueryIdle+0x4c/0xbc) from [<c0475e0c>] (_TryToIdleGPU+0x70/0x12c)

Mutex protection is not necessary for interrupt handling, because GPU clock is only turned off
by interrupt worker thread during clock gating.

Date: Apr 11, 2014
Signed-off-by: Xianzhong <b07117@freescale.com>
Acked-by: Jason Liu

1 files changed, 37 insertions, 0 deletions

diff --git a/drivers/mxc/gpu-viv/hal/os/linux/kernel/gc_hal_kernel_os.c b/drivers/mxc/gpu-viv/hal/os/linux/kernel/gc_hal_kernel_os.c
index 91e58f0a91b9..35d479f7290c 100644
--- a/drivers/mxc/gpu-viv/hal/os/linux/kernel/gc_hal_kernel_os.c
+++ b/drivers/mxc/gpu-viv/hal/os/linux/kernel/gc_hal_kernel_os.c
@@ -211,6 +211,9 @@ struct _gckOS
 
     /* workqueue for os timer. */
     struct workqueue_struct *   workqueue;
+
+    int                         gpu_clk_on[3];
+    struct mutex                gpu_clk_mutex;
 };
 
 typedef struct _gcsSIGNAL * gcsSIGNAL_PTR;
@@ -1111,6 +1114,8 @@ gckOS_Construct(
         gcmkONERROR(gcvSTATUS_OUT_OF_MEMORY);
     }
 
+    mutex_init(&os->gpu_clk_mutex);
+
     /* Return pointer to the gckOS object. */
     *Os = os;
 
@@ -2410,7 +2415,17 @@ gckOS_ReadRegisterEx(
     gcmkVERIFY_ARGUMENT(Address < Os->device->requestedRegisterMemSizes[Core]);
     gcmkVERIFY_ARGUMENT(Data != gcvNULL);
 
+    if(Address != 0x10) mutex_lock(&Os->gpu_clk_mutex);
+    BUG_ON(!Os->gpu_clk_on[Core]);
+
+    if(Address)
+    {
+        gctUINT32 AQHiClockControl = readl((gctUINT8 *)Os->device->registerBases[Core]);
+        BUG_ON((AQHiClockControl & 0x3) == 0x3);
+    }
+
     *Data = readl((gctUINT8 *)Os->device->registerBases[Core] + Address);
+    if(Address != 0x10) mutex_unlock(&Os->gpu_clk_mutex);
 
     /* Success. */
     gcmkFOOTER_ARG("*Data=0x%08x", *Data);
@@ -2460,7 +2475,17 @@ gckOS_WriteRegisterEx(
 
     gcmkVERIFY_ARGUMENT(Address < Os->device->requestedRegisterMemSizes[Core]);
 
+    mutex_lock(&Os->gpu_clk_mutex);
+    BUG_ON(!Os->gpu_clk_on[Core]);
+
+    if(Address)
+    {
+        gctUINT32 AQHiClockControl = readl((gctUINT8 *)Os->device->registerBases[Core]);
+        BUG_ON((AQHiClockControl & 0x3) == 0x3);
+    }
+
     writel(Data, (gctUINT8 *)Os->device->registerBases[Core] + Address);
+    mutex_unlock(&Os->gpu_clk_mutex);
 
     /* Success. */
     gcmkFOOTER_NO();
@@ -6983,6 +7008,7 @@ gckOS_SetGPUPower(
 #if LINUX_VERSION_CODE < KERNEL_VERSION(3,5,0)
     if (Clock == gcvTRUE) {
         if (oldClockState == gcvFALSE) {
+            mutex_lock(&Os->gpu_clk_mutex);
             switch (Core) {
             case gcvCORE_MAJOR:
                 clk_enable(clk_3dcore);
@@ -7000,9 +7026,12 @@ gckOS_SetGPUPower(
             default:
                 break;
             }
+            Os->gpu_clk_on[Core] = 1;
+            mutex_unlock(&Os->gpu_clk_mutex);
         }
     } else {
         if (oldClockState == gcvTRUE) {
+            mutex_lock(&Os->gpu_clk_mutex);
             switch (Core) {
             case gcvCORE_MAJOR:
                 if (cpu_is_mx6q())
@@ -7020,11 +7049,14 @@ gckOS_SetGPUPower(
             default:
                 break;
             }
+            Os->gpu_clk_on[Core] = 0;
+            mutex_unlock(&Os->gpu_clk_mutex);
         }
     }
 #else
     if (Clock == gcvTRUE) {
         if (oldClockState == gcvFALSE) {
+            mutex_lock(&Os->gpu_clk_mutex);
             switch (Core) {
             case gcvCORE_MAJOR:
                 clk_prepare(clk_3dcore);
@@ -7049,9 +7081,12 @@ gckOS_SetGPUPower(
             default:
                 break;
             }
+            Os->gpu_clk_on[Core] = 1;
+            mutex_unlock(&Os->gpu_clk_mutex);
         }
     } else {
         if (oldClockState == gcvTRUE) {
+            mutex_lock(&Os->gpu_clk_mutex);
             switch (Core) {
             case gcvCORE_MAJOR:
                 clk_disable(clk_3dshader);
@@ -7076,6 +7111,8 @@ gckOS_SetGPUPower(
             default:
                 break;
             }
+            Os->gpu_clk_on[Core] = 0;
+            mutex_unlock(&Os->gpu_clk_mutex);
         }
     }
 #endif