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Subject: Re: [PATCH 2/2] imx-drm: ipuv3-plane: fix kernel Oops in
ipu_dp_put()
From: Philipp Zabel
To: Shawn Guo
Date: Tue, 19 Aug 2014 15:59:38 +0200
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Hi Shawn,
Am Dienstag, den 19.08.2014, 17:49 +0800 schrieb Shawn Guo:
> Unbinding imx-hdmi or imx-ldb driver triggers a kernel Oops in function
> ipu_dp_put() as below.
>
> $ echo 120000.hdmi > /sys/devices/soc0/soc/2000000.aips-bus/120000.hdmi/driver/unbind
[...]
> From the call stack, the issue is caused by that ipu_dp_put() is called
> from ipu_plane_dpms() with ipu_plane->dp being NULL. Rather than
> being called unconditionally, ipu_dp_put() should be called only when
> ipu_plane->dp is valid, just like what ipu_plane_put_resources() does.
> Acutally, all those ipu_*_put() calls in ipu_plane_dpms() are
> unnecessary, because the only occurrence of ipu_plane_dpms() with 'mode'
> not being DRM_MODE_DPMS_ON is from function ipu_disable_plane(), which
> already has a ipu_plane_put_resources() call right after
> ipu_plane_dpms().
>
> The patch fixes above kernel Oops by removing those buggy and
> unnecessary ipu_*_put() calls from ipu_plane_dpms().
>
> Signed-off-by: Shawn Guo
> ---
> drivers/staging/imx-drm/ipuv3-plane.c | 9 ++-------
> 1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/staging/imx-drm/ipuv3-plane.c b/drivers/staging/imx-drm/ipuv3-plane.c
> index 6f393a11f44d..a79ae7731a03 100644
> --- a/drivers/staging/imx-drm/ipuv3-plane.c
> +++ b/drivers/staging/imx-drm/ipuv3-plane.c
> @@ -274,15 +274,10 @@ static void ipu_plane_dpms(struct ipu_plane *ipu_plane, int mode)
> if (enable == ipu_plane->enabled)
> return;
>
> - if (enable) {
> + if (enable)
> ipu_plane_enable(ipu_plane);
> - } else {
> + else
> ipu_plane_disable(ipu_plane);
> -
> - ipu_idmac_put(ipu_plane->ipu_ch);
> - ipu_dmfc_put(ipu_plane->dmfc);
> - ipu_dp_put(ipu_plane->dp);
> - }
> }
>
> /*
we could then remove ipu_plane_dpms completely:
---
drivers/staging/imx-drm/ipuv3-plane.c | 23 ++++-------------------
1 file changed, 4 insertions(+), 19 deletions(-)
diff --git a/drivers/staging/imx-drm/ipuv3-plane.c b/drivers/staging/imx-drm/ipuv3-plane.c
index b2d1bb2..6987e16 100644
--- a/drivers/staging/imx-drm/ipuv3-plane.c
+++ b/drivers/staging/imx-drm/ipuv3-plane.c
@@ -290,23 +290,6 @@ void ipu_plane_disable(struct ipu_plane *ipu_plane)
ipu_dp_disable(ipu_plane->ipu);
}
-static void ipu_plane_dpms(struct ipu_plane *ipu_plane, int mode)
-{
- bool enable;
-
- DRM_DEBUG_KMS("mode = %d", mode);
-
- enable = (mode == DRM_MODE_DPMS_ON);
-
- if (enable == ipu_plane->enabled)
- return;
-
- if (enable)
- ipu_plane_enable(ipu_plane);
- else
- ipu_plane_disable(ipu_plane);
-}
-
/*
* drm_plane API
*/
@@ -340,7 +323,8 @@ static int ipu_update_plane(struct drm_plane *plane, struct drm_crtc *crtc,
plane->crtc, crtc);
plane->crtc = crtc;
- ipu_plane_dpms(ipu_plane, DRM_MODE_DPMS_ON);
+ if (!ipu_plane->enabled)
+ ipu_plane_enable(ipu_plane);
return 0;
}
@@ -351,7 +335,8 @@ static int ipu_disable_plane(struct drm_plane *plane)
DRM_DEBUG_KMS("[%d] %s\n", __LINE__, __func__);
- ipu_plane_dpms(ipu_plane, DRM_MODE_DPMS_OFF);
+ if (ipu_plane->enabled)
+ ipu_plane_disable(ipu_plane);
ipu_plane_put_resources(ipu_plane);