Re: [PATCH 12/13] drm/i915: remove in_dbg_master check from intel_fbc.c

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On 11/04/2015 11:10 AM, Paulo Zanoni wrote:
> From our maintainer Daniel Vetter a few days ago:
>   "Oh dear this is dead code. kdbg uses the fbcon, which always uses
>   untiled, which means fbc will never be enabled. Also we have 0 users
>   and 0 test coverage for kdbg on top of i915 (Jesse implemented it
>   for fun years back). Imo just remove all this code."
> 
> Adding to what Daniel said: for kgdboc's KMS support,
> intel_pipe_set_base_atomic() already manually disables FBC, so we
> won't do the in_dbg_master() check there. This is essentially a revert
> of:
> 
> commit c924b934d0cd14a4559611da91f28f59acebe32a
> Author: Jason Wessel <jason.wessel@windriver.com>
> Date:   Thu Aug 5 09:22:32 2010 -0500
>     i915: when kgdb is active display compression should be off
> 
> Besides, it is not clear what is the exact problem caused by FBC, and
> why other features such as PSR, DRRS, IPS and RPM are not also
> checking for in_dbg_master(). IMHO we should either remove the code as
> suggested by Daniel or we add some nice comments explaining why is FBC
> so special.
> 
> v2: Rebase due to new patch order.
> 
> Cc: Jason Wessel <jason.wessel@windriver.com>
> Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_fbc.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
> index 8e806be..e496cb0 100644
> --- a/drivers/gpu/drm/i915/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/intel_fbc.c
> @@ -890,12 +890,6 @@ static void __intel_fbc_update(struct drm_i915_private *dev_priv)
>  		goto out_disable;
>  	}
>  
> -	/* If the kernel debugger is active, always disable compression */
> -	if (in_dbg_master()) {
> -		set_no_fbc_reason(dev_priv, "Kernel debugger is active");
> -		goto out_disable;
> -	}
> -
>  	/* WaFbcExceedCdClockThreshold:hsw,bdw */
>  	if ((IS_HASWELL(dev_priv) || IS_BROADWELL(dev_priv)) &&
>  	    ilk_pipe_pixel_rate(crtc->config) >=
> 

Yeah looks fine.  I haven't had any bug reports from the kdboc work, so
I guess that means no one is using it. :)

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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