[Intel-gfx] [PATCH 5/7] drm/i915: WARN on unclaimed registers

[Ben Widawsky]

On Fri, 25 Jan 2013 18:57:40 -0200
Paulo Zanoni <przanoni at gmail.com> wrote:

> From: Paulo Zanoni <paulo.r.zanoni at intel.com>
> 
> While debugging these "unclaimed register" problems I concluded that
> having a backtrace is way much more useful than having the register
> address, since in a lot of cases the register address print on the
> message is not the register we're looking for.
> 
> We must fix all the "unclaimed register" problems, so if dmesg gets
> too polluted it means we're too bugged.
> 
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>

As I mentioned internally, I'd still prefer
if (WARN_ON(I915_READ_NOTRACE(FPGA_DBG) & FPGA_DBG_RM_NOCLAIM))

because I don't think the message is particularly useful with a
backtrace in hand.

Also on second thought since the internal review, it's probably not
super useful to have the WARN in the UNCLAIMED_REG_CLEAR, because as
you've mentioned before, it's usually from snd-hda or something like
that. So I'd probably get rid of that unless someone else sees a super
cool usage for it.


With or without painting my color:
Reviewed-by: Ben Widawsky <ben at bwidawsk.net>

> ---
>  drivers/gpu/drm/i915/i915_drv.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 422dfc6..bc0eb88 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1227,14 +1227,14 @@ ilk_dummy_write(struct drm_i915_private *dev_priv)
>  #define UNCLAIMED_REG_CLEAR(dev_priv, reg, op) \
>  	if (IS_HASWELL(dev_priv->dev) && \
>  	    (I915_READ_NOTRACE(FPGA_DBG) & FPGA_DBG_RM_NOCLAIM)) { \
> -		DRM_ERROR("Unclaimed register before %x (%c)\n", reg, op); \
> +		WARN(1, "Unclaimed register before %x (%c)\n", reg, op); \
>  		I915_WRITE_NOTRACE(FPGA_DBG, FPGA_DBG_RM_NOCLAIM); \
>  	}
>  
>  #define UNCLAIMED_REG_CHECK(dev_priv, reg, op) \
>  	if (IS_HASWELL(dev_priv->dev) && \
>  	    (I915_READ_NOTRACE(FPGA_DBG) & FPGA_DBG_RM_NOCLAIM)) { \
> -		DRM_ERROR("Unclaimed register %x (%c)\n", reg, op); \
> +		WARN(1, "Unclaimed register %x (%c)\n", reg, op); \
>  		I915_WRITE_NOTRACE(FPGA_DBG, FPGA_DBG_RM_NOCLAIM); \
>  	}
>  



-- 
Ben Widawsky, Intel Open Source Technology Center