Re: [PATCH] drm/i915: Fix up the forcewake timer initialization

[Ben Widawsky <benjamin.widawsky@intel.com>]

On Tue, Mar 18, 2014 at 04:31:03PM +0100, Daniel Vetter wrote:
> This is a regression introduced in
> 
> commit 0294ae7b44bba7ab0d4cef9a8736287f38bdb4fd
> Author: Chris Wilson <chris@chris-wilson.co.uk>
> Date:   Thu Mar 13 12:00:29 2014 +0000
> 
>     drm/i915: Consolidate forcewake resetting to a single function
> 
> The reordered setup sequence ended up calling del_timer_sync before
> the timer was set up correctly, resulting in endless hilarity when
> loading the driver.
> 
> Compared to Ben's patch (which moved around the setup_timer call to
> sanitize_early) this moves the sanitize_early call around in the
> driver load call. This way we avoid calling setup_timer again in the
> resume code (where we also call sanitize_early).
> 
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala@intel.com>
> Cc: Ben Widawsky <benjamin.widawsky@intel.com>
> Tested-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76242
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/i915/i915_dma.c     | 2 --
>  drivers/gpu/drm/i915/intel_uncore.c | 2 ++
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index e4d2b9f15ae2..9faee49f210d 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -1608,8 +1608,6 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
>  		goto put_bridge;
>  	}
>  
> -	intel_uncore_early_sanitize(dev);
> -
>  	/* This must be called before any calls to HAS_PCH_* */
>  	intel_detect_pch(dev);
>  
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index e2e328d86aff..c3832d9270a6 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -736,6 +736,8 @@ void intel_uncore_init(struct drm_device *dev)
>  	setup_timer(&dev_priv->uncore.force_wake_timer,
>  		    gen6_force_wake_timer, (unsigned long)dev_priv);
>  
> +	intel_uncore_early_sanitize(dev);
> +
>  	if (IS_VALLEYVIEW(dev)) {
>  		dev_priv->uncore.funcs.force_wake_get = __vlv_force_wake_get;
>  		dev_priv->uncore.funcs.force_wake_put = __vlv_force_wake_put;

If you only want to setup_timer once, the setup_timer call should be in
intel_uncore_init() which is the only one called only at load time. And
of course, this is where the bug is. Otherwise, thaw calls
uncore_early_sanitize, which will setup_timer again (which I thought was
your complaint with my original patch).

How about this, (only minimally tested):

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index e2e328d..7ef5aa3 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -387,8 +387,6 @@ void intel_uncore_early_sanitize(struct drm_device *dev)
        if (IS_GEN6(dev) || IS_GEN7(dev))
                __raw_i915_write32(dev_priv, GTFIFODBG,
                                   __raw_i915_read32(dev_priv, GTFIFODBG));
-
-       intel_uncore_forcewake_reset(dev, false);
 }
 
 void intel_uncore_sanitize(struct drm_device *dev)
@@ -413,6 +411,8 @@ void intel_uncore_sanitize(struct drm_device *dev)
                mutex_unlock(&dev_priv->rps.hw_lock);
 
        }
+
+       intel_uncore_forcewake_reset(dev, false);
 }
 
 /*
@@ -846,7 +846,6 @@ void intel_uncore_fini(struct drm_device *dev)
 {
        /* Paranoia: make sure we have disabled everything before we exit. */
        intel_uncore_sanitize(dev);
-       intel_uncore_forcewake_reset(dev, false);
 }
 


-- 
Ben Widawsky, Intel Open Source Technology Center