[Intel-gfx] [PATCH] drm/i915: Busy-spin wait_for condition in atomic contexts

[Jesse Barnes]

On Thu, 24 Mar 2011 19:55:59 +0000
Chris Wilson <chris at chris-wilson.co.uk> wrote:

> During modesetting, we need to wait for the hardware to report
> readiness by polling the registers. Normally, we call msleep() between
> reads, because some state changes may take a whole vblank or more
> to complete. However during a panic, we are in an atomic context and
> cannot sleep. Instead, busy spin polling the termination condition.
> 
> References: https://bugzilla.kernel.org/show_bug.cgi?id=31772
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/intel_drv.h |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 5daa991..ac70398 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -39,7 +39,7 @@
>  			ret__ = -ETIMEDOUT;				\
>  			break;						\
>  		}							\
> -		if (W && !in_dbg_master()) msleep(W);			\
> +		if (W && !(in_dbg_master() || in_atomic())) msleep(W);	\
>  	}								\
>  	ret__;								\
>  })

Yeah, this should be fine; though I think in_dbg_master always implies
in_atomic too, so you could just collapse the check.

Jason, can you confirm that?

-- 
Jesse Barnes, Intel Open Source Technology Center