[PATCH 1/2] drm/i915: Revert wait for vblank to prevent X refresh issues

[PATCH 1/2] drm/i915: Revert wait for vblank to prevent X refresh issues

[Sitsofe Wheeler]

In commit 9d0498a2bf7455159b317f19531a3e5db2ecc9c4 20ms waits were
converted into vblank waits. One of these caused tearing, mode detection
and redraw issues on an EeePC 900 with a more recent intel userspace (
http://lkml.org/lkml/2010/8/23/432 ). Restoring the 20ms wait resolves
the issue.
---
 drivers/gpu/drm/i915/intel_display.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 23157e1..116d938 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4539,7 +4539,7 @@ struct drm_crtc *intel_get_load_detect_pipe(struct intel_encoder *intel_encoder,
 		encoder_funcs->commit(encoder);
 	}
 	/* let the connector get through one full cycle before testing */
-	intel_wait_for_vblank(dev, intel_crtc->pipe);
+	msleep(20);
 
 	return crtc;
 }
-- 
1.7.1

[PATCH 1/2] drm/i915: Revert wait for vblank to prevent X refresh issues

[Sitsofe Wheeler]

In commit 9d0498a2bf7455159b317f19531a3e5db2ecc9c4 20ms waits were
converted into vblank waits. One of these caused tearing, mode detection
and redraw issues on an EeePC 900 with a more recent intel userspace (
http://lkml.org/lkml/2010/8/23/432 ). Restoring the 20ms wait resolves
the issue.

Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>
---
 drivers/gpu/drm/i915/intel_display.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 23157e1..116d938 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4539,7 +4539,7 @@ struct drm_crtc *intel_get_load_detect_pipe(struct intel_encoder *intel_encoder,
 		encoder_funcs->commit(encoder);
 	}
 	/* let the connector get through one full cycle before testing */
-	intel_wait_for_vblank(dev, intel_crtc->pipe);
+	msleep(20);
 
 	return crtc;
 }
-- 
1.7.1

[PATCH 2/2] drm/i915: Revert extra intel_wait_for_vblank to prevent stalls.

[Sitsofe Wheeler]

With the extra intel_wait_for_vblank added in commit
9d0498a2bf7455159b317f19531a3e5db2ecc9c4 periodic stalls were being
triggered (which were detected by i915_hangcheck_elapsed). Partially
revert this change for now.

Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>
---
 drivers/gpu/drm/i915/intel_display.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 116d938..534f1fa 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2379,8 +2379,10 @@ static void i9xx_crtc_dpms(struct drm_crtc *crtc, int mode)
 			I915_READ(dspbase_reg);
 		}
 
-		/* Wait for vblank for the disable to take effect */
-		intel_wait_for_vblank_off(dev, pipe);
+		if (!IS_I9XX(dev)) {
+			/* Wait for vblank for the disable to take effect */
+			intel_wait_for_vblank_off(dev, pipe);
+		}
 
 		/* Don't disable pipe A or pipe A PLLs if needed */
 		if (pipeconf_reg == PIPEACONF &&
-- 
1.7.1

Re: [PATCH 2/2] drm/i915: Revert extra intel_wait_for_vblank to prevent stalls.

[Jesse Barnes]

On Tue, 24 Aug 2010 16:56:16 +0100
Sitsofe Wheeler <sitsofe@yahoo.com> wrote:

> With the extra intel_wait_for_vblank added in commit
> 9d0498a2bf7455159b317f19531a3e5db2ecc9c4 periodic stalls were being
> triggered (which were detected by i915_hangcheck_elapsed). Partially
> revert this change for now.
> 
> Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 116d938..534f1fa 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -2379,8 +2379,10 @@ static void i9xx_crtc_dpms(struct drm_crtc *crtc, int mode)
>  			I915_READ(dspbase_reg);
>  		}
>  
> -		/* Wait for vblank for the disable to take effect */
> -		intel_wait_for_vblank_off(dev, pipe);
> +		if (!IS_I9XX(dev)) {
> +			/* Wait for vblank for the disable to take effect */
> +			intel_wait_for_vblank_off(dev, pipe);
> +		}
>  
>  		/* Don't disable pipe A or pipe A PLLs if needed */
>  		if (pipeconf_reg == PIPEACONF &&

Hm why would we be triggering the hangcheck timer due to this code?
I'd rather figure that out and fix it before covering it up like this.

Wait for vblank off will spin until the display line reg stops
incrementing, so it's important that we flush any previous writes to
shut off the pipe before waiting.  So adding a POSTING_READ() above it
might help?  But that still doesn't explain why it would cause the
hangcheck timer to notice a hang...

-- 
Jesse Barnes, Intel Open Source Technology Center

Re: [PATCH 1/2] drm/i915: Revert wait for vblank to prevent X refresh issues

[Jesse Barnes]

On Tue, 24 Aug 2010 16:53:59 +0100
Sitsofe Wheeler <sitsofe@yahoo.com> wrote:

> In commit 9d0498a2bf7455159b317f19531a3e5db2ecc9c4 20ms waits were
> converted into vblank waits. One of these caused tearing, mode detection
> and redraw issues on an EeePC 900 with a more recent intel userspace (
> http://lkml.org/lkml/2010/8/23/432 ). Restoring the 20ms wait resolves
> the issue.
> 
> Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 23157e1..116d938 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -4539,7 +4539,7 @@ struct drm_crtc *intel_get_load_detect_pipe(struct intel_encoder *intel_encoder,
>  		encoder_funcs->commit(encoder);
>  	}
>  	/* let the connector get through one full cycle before testing */
> -	intel_wait_for_vblank(dev, intel_crtc->pipe);
> +	msleep(20);
>  
>  	return crtc;
>  }

Wow, tearing, mode detection and redraw problems all because of this
line?  Maybe because we wait for a longer period here now?  Can you
check and see if we're timing out in the wait_for_vblank function?

-- 
Jesse Barnes, Intel Open Source Technology Center