Re: [PATCH] drm/i915: add missing forcewake put on i915_wa_registers()

Daniel Vetter
2014-10-21T17:40:28Z

On Tue, Oct 21, 2014 at 02:58:08PM -0200, Paulo Zanoni wrote:
> From: Paulo Zanoni <paulo.r.zanoni@intel.com>
>
> Otherwise, a simple "cat" to the debugfs file can make the machine use
> much more power than needed, and prevent it from runtime suspending.
>
> Related commit:
>
> commit 8452e1d173a16d9812422a2272c4ab0f0ba81057
> Author: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> Date: Tue Oct 7 17:21:26 2014 +0300
> drm/i915: Build workaround list in ring initialization
>
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> Cc: Arun Siluvery <arun.siluvery@linux.intel.com>
> Testcase: igt/pm_rpm/debugfs-read
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>

tbh I'm not even sure we want to do the manual forcewake get here -
I915_READ will do it for us, and this is a debug interface. So no one
should care about perf. Mika, is that right? If so I'd like to merge the
inverse patch which drops the fw_get.
-Daniel

> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 9600285..36a4baa 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -2671,6 +2671,7 @@ static int i915_wa_registers(struct seq_file *m, void *unused)
> addr, value, mask, read, ok ? "OK" : "FAIL");
> }
>
> + gen6_gt_force_wake_put(dev_priv, FORCEWAKE_ALL);
> intel_runtime_pm_put(dev_priv);
> mutex_unlock(&dev->struct_mutex);
>
> --
> 2.1.1
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch