ENGR00253927 IPU: Fix NULL pointer bug when BG EOF interrupt occur early

Fix NULL pointer bug when IPU BG EOF interrupt occur before register irq handler
It can be reproduced on MIPI DSI display on i.mx6dl SabreSD board.

The sequence is:
a) enable display channel
b) pan display (fb_set_var()) -> ipu_enable_irq
c) ipu_request_irq
If an EOF interrupt comes before c and after b, the issue happens.

Signed-off-by: Wayne Zou <b36644@freescale.com>

diff --git a/drivers/video/mxc/mxc_ipuv3_fb.c b/drivers/video/mxc/mxc_ipuv3_fb.c
index f8dd59e355ea3d47f45f0d017200bd550fcb605b..4c98d51f13b0bc13045031a04e6fff278bb63f09 100644 (file)
--- a/drivers/video/mxc/mxc_ipuv3_fb.c
+++ b/drivers/video/mxc/mxc_ipuv3_fb.c
@@ -2040,6 +2040,31 @@ static int mxcfb_register(struct fb_info *fbi)
        fb_var_to_videomode(&m, &fbi->var);
        fb_add_videomode(&m, &fbi->modelist);
 
+       if (ipu_request_irq(mxcfbi->ipu, mxcfbi->ipu_ch_irq,
+               mxcfb_irq_handler, IPU_IRQF_ONESHOT, MXCFB_NAME, fbi) != 0) {
+               dev_err(fbi->device, "Error registering EOF irq handler.\n");
+               ret = -EBUSY;
+               goto err0;
+       }
+       ipu_disable_irq(mxcfbi->ipu, mxcfbi->ipu_ch_irq);
+       if (ipu_request_irq(mxcfbi->ipu, mxcfbi->ipu_ch_nf_irq,
+               mxcfb_nf_irq_handler, IPU_IRQF_ONESHOT, MXCFB_NAME, fbi) != 0) {
+               dev_err(fbi->device, "Error registering NFACK irq handler.\n");
+               ret = -EBUSY;
+               goto err1;
+       }
+       ipu_disable_irq(mxcfbi->ipu, mxcfbi->ipu_ch_nf_irq);
+
+       if (mxcfbi->ipu_alp_ch_irq != -1)
+               if (ipu_request_irq(mxcfbi->ipu, mxcfbi->ipu_alp_ch_irq,
+                               mxcfb_alpha_irq_handler, IPU_IRQF_ONESHOT,
+                                       MXCFB_NAME, fbi) != 0) {
+                       dev_err(fbi->device, "Error registering alpha irq "
+                                       "handler.\n");
+                       ret = -EBUSY;
+                       goto err2;
+               }
+
        if (!mxcfbi->late_init) {
                fbi->var.activate |= FB_ACTIVATE_FORCE;
                console_lock();
@@ -2047,11 +2072,20 @@ static int mxcfb_register(struct fb_info *fbi)
                ret = fb_set_var(fbi, &fbi->var);
                fbi->flags &= ~FBINFO_MISC_USEREVENT;
                console_unlock();
+               if (ret < 0) {
+                       dev_err(fbi->device, "Error fb_set_var ret:%d\n", ret);
+                       goto err3;
+               }
 
                if (mxcfbi->next_blank == FB_BLANK_UNBLANK) {
                        console_lock();
-                       fb_blank(fbi, FB_BLANK_UNBLANK);
+                       ret = fb_blank(fbi, FB_BLANK_UNBLANK);
                        console_unlock();
+                       if (ret < 0) {
+                               dev_err(fbi->device,
+                                       "Error fb_blank ret:%d\n", ret);
+                               goto err4;
+                       }
                }
        } else {
                /*
@@ -2067,44 +2101,13 @@ static int mxcfb_register(struct fb_info *fbi)
                }
        }
 
-       if (ipu_request_irq(mxcfbi->ipu, mxcfbi->ipu_ch_irq,
-               mxcfb_irq_handler, IPU_IRQF_ONESHOT, MXCFB_NAME, fbi) != 0) {
-               dev_err(fbi->device, "Error registering EOF irq handler.\n");
-               ret = -EBUSY;
-               goto err0;
-       }
-       ipu_disable_irq(mxcfbi->ipu, mxcfbi->ipu_ch_irq);
-       if (ipu_request_irq(mxcfbi->ipu, mxcfbi->ipu_ch_nf_irq,
-               mxcfb_nf_irq_handler, IPU_IRQF_ONESHOT, MXCFB_NAME, fbi) != 0) {
-               dev_err(fbi->device, "Error registering NFACK irq handler.\n");
-               ret = -EBUSY;
-               goto err1;
-       }
-       ipu_disable_irq(mxcfbi->ipu, mxcfbi->ipu_ch_nf_irq);
-
-       if (mxcfbi->ipu_alp_ch_irq != -1)
-               if (ipu_request_irq(mxcfbi->ipu, mxcfbi->ipu_alp_ch_irq,
-                               mxcfb_alpha_irq_handler, IPU_IRQF_ONESHOT,
-                                       MXCFB_NAME, fbi) != 0) {
-                       dev_err(fbi->device, "Error registering alpha irq "
-                                       "handler.\n");
-                       ret = -EBUSY;
-                       goto err2;
-               }
 
        ret = register_framebuffer(fbi);
        if (ret < 0)
-               goto err3;
+               goto err5;
 
        return ret;
-err3:
-       if (mxcfbi->ipu_alp_ch_irq != -1)
-               ipu_free_irq(mxcfbi->ipu, mxcfbi->ipu_alp_ch_irq, fbi);
-err2:
-       ipu_free_irq(mxcfbi->ipu, mxcfbi->ipu_ch_nf_irq, fbi);
-err1:
-       ipu_free_irq(mxcfbi->ipu, mxcfbi->ipu_ch_irq, fbi);
-err0:
+err5:
        if (mxcfbi->next_blank == FB_BLANK_UNBLANK) {
                console_lock();
                if (!mxcfbi->late_init)
@@ -2116,6 +2119,15 @@ err0:
                }
                console_unlock();
        }
+err4:
+err3:
+       if (mxcfbi->ipu_alp_ch_irq != -1)
+               ipu_free_irq(mxcfbi->ipu, mxcfbi->ipu_alp_ch_irq, fbi);
+err2:
+       ipu_free_irq(mxcfbi->ipu, mxcfbi->ipu_ch_nf_irq, fbi);
+err1:
+       ipu_free_irq(mxcfbi->ipu, mxcfbi->ipu_ch_irq, fbi);
+err0:
        return ret;
 }