Re: [PATCH] drm/i915: fix corruptions on i8xx due to relaxed fencing

["Daniel Vetter" <daniel@ffwll.ch>]

Am Mi, 23.02.2011, 07:59 schrieb Indan Zupancic:
> On Tue, February 22, 2011 18:25, Daniel Vetter wrote:
>> It looks like gen2 has a peculiar interleaved 2-row inter-tile
>> layout. Probably inherited from i81x which had 2kb tiles (which
>> naturally fit an even-number-of-tile-rows scheme to fit onto 4kb
>> pages). There is no other mention of this in any docs (also not
>> in the Intel internal documention according to Chris Wilson).
>>
>> Problem manifests itself in corruptions in the second half of the
>> last tile row (if the bo has an odd number of tiles). Which can
>> only happen with relaxed tiling (introduced in a00b10c360b35d6431a9).
>>
>> So reject set_tiling calls that don't satisfy this constrain to
>> prevent broken userspace from causing havoc. While at it, also
>> check the size for newer chipsets.
>>
>> LKML: https://lkml.org/lkml/2011/2/19/5
>> Reported-by: Indan Zupancic <indan@nul.nu>
>> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>> ---
>>  drivers/gpu/drm/i915/i915_gem_tiling.c |   16 +++++++++++++++-
>>  1 files changed, 15 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c
>> b/drivers/gpu/drm/i915/i915_gem_tiling.c
>> index 22a32b9..79a04fd 100644
>> --- a/drivers/gpu/drm/i915/i915_gem_tiling.c
>> +++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
>> @@ -184,7 +184,7 @@ i915_gem_detect_bit_6_swizzle(struct drm_device
>> *dev)
>>  static bool
>>  i915_tiling_ok(struct drm_device *dev, int stride, int size, int
>> tiling_mode)
>>  {
>> -	int tile_width;
>> +	int tile_width, tile_height;
>>
>>  	/* Linear is always fine */
>>  	if (tiling_mode == I915_TILING_NONE)
>> @@ -215,6 +215,20 @@ i915_tiling_ok(struct drm_device *dev, int stride,
>> int size, int
>> tiling_mode)
>>  		}
>>  	}
>>
>> +	if (IS_GEN2(dev) ||
>> +	    (tiling_mode == I915_TILING_Y && HAS_128_BYTE_Y_TILING(dev)))
>> +		tile_height = 32;
>> +	else
>> +		tile_height = 8;
>> +	/* i8xx is strange: It has 2 interleaved rows of tiles, so needs an
>> even
>> +	 * number of tile rows. */
>> +	if (IS_GEN2(dev))
>> +		tile_height *= 2;
>> +
>> +	/* Size needs to be aligned to a full tile row */
>> +	if (size & (tile_height * stride - 1))
>> +		return false;
>> +
>>  	/* 965+ just needs multiples of tile width */
>>  	if (INTEL_INFO(dev)->gen >= 4) {
>>  		if (stride & (tile_width - 1))
>
> Tested-by: Indan Zupancic <indan@nul.nu>
>
> I tested with this patch and without the other ones you send and the
> corruption
> is indeed gone.
>
> Not sure why you dropped lkml from CC, now people who stuble upon it don't
> see
> the ending...

Random incoherency in my brain. Re-added to cc.
- Daniel