Re: [PATCH] drm/i915: Enforce that CS packets are qword aligned

From: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Enforce that CS packets are qword aligned
Date: Mon, 24 Jul 2017 09:06:28 +0100	[thread overview]
Message-ID: <9af1c079-eadd-dbb3-eec7-81feda52f2ff@linux.intel.com> (raw)
In-Reply-To: <20170721161101.1618-1-chris@chris-wilson.co.uk>


On 21/07/2017 17:11, Chris Wilson wrote:
> We require the caller to ensure that the packets they wish to emit into
> the CS ring are qword aligned (i.e. have an even number of dwords).
> Double check this.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> ---
>   drivers/gpu/drm/i915/intel_ringbuffer.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index aa59290cb8bf..0b06f66507a0 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -1397,6 +1397,9 @@ u32 *intel_ring_begin(struct drm_i915_gem_request *req,
>   	unsigned int total_bytes;
>   	u32 *cs;
>   
> +	/* Packets must be qword aligned. */
> +	GEM_BUG_ON(num_dwords & 1);
> +
>   	total_bytes = bytes + req->reserved_space;
>   	GEM_BUG_ON(total_bytes > ring->effective_size);
>   
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko
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