2015-11-18 13:59 GMT-02:00 Daniel Vetter <daniel@xxxxxxxx>:
> On Fri, Nov 13, 2015 at 03:12:41PM -0200, Paulo Zanoni wrote:
>> Hello
>>
>> I've been carrying some local IGT patches that reduced the size of buffers
>> created by igt_create_fb() so they would fit the stolen memory, but when I
>> decided to test the tree without them, I concluded the lack of sane sizes was
>> even causing test failures. So here's my attempt to fix this. This series alone
>> should help reducing the number of kms_frontbuffer_tracking failures seen by QA.
>>
>> The last few patches make the FBC tests a little harder. They are all based on
>> the feedback I got from the last patches I sent.
>
> The point of a helper library is that it helps, not that every caller has
> to work around it's choice of size and stride.
Judging by the amount of users, it is helping even without my changes :)
>
> The only thing we need to do here is fix up the selection of stride and
> size to make it not pick the super-conservative value that work even on
> gen2&3. Something like:
>
> diff --git a/lib/igt_fb.c b/lib/igt_fb.c
> index 13a6a34982e0..9eb97952ed95 100644
> --- a/lib/igt_fb.c
> +++ b/lib/igt_fb.c
> @@ -87,21 +87,26 @@ static int create_bo_for_fb(int fd, int width, int height, int bpp,
> if (tiling != LOCAL_DRM_FORMAT_MOD_NONE) {
> int v;
>
> - /* Round the tiling up to the next power-of-two and the
> - * region up to the next pot fence size so that this works
> - * on all generations.
> - *
> - * This can still fail if the framebuffer is too large to
> - * be tiled. But then that failure is expected.
> - */
> -
> - v = width * bpp / 8;
> - for (stride = 512; stride < v; stride *= 2)
> - ;
> -
> - v = stride * height;
> - for (size = 1024*1024; size < v; size *= 2)
> - ;
> + if (gen < 4) {
> + /* Round the tiling up to the next power-of-two and the
> + * region up to the next pot fence size so that this works
> + * on all generations.
> + *
> + * This can still fail if the framebuffer is too large to
> + * be tiled. But then that failure is expected.
> + */
> +
> + v = width * bpp / 8;
> + for (stride = 512; stride < v; stride *= 2)
> + ;
> +
> + v = stride * height;
> + for (size = 1024*1024; size < v; size *= 2)
> + ;
> + } else {
> + stride = ALIGN(stride, 512);
> + size = ALIGN(size, stride * 32);
Shouldn't it be size = stride * ALIGN(height, 32)?
(it still wouldn't be the minimal size, but would be close to it)
> + }
> } else {
> /* Scan-out has a 64 byte alignment restriction */
> stride = (width * (bpp / 8) + 63) & ~63;
>
>
> Or whatever is the right thing to pick that works on gen4+.
While that sounds like an improvement, it won't solve the
kms_frontbuffer_tracking problem where we want to specify size+stride
since we want all buffers using the same size+stride independently of
tiling/no-tiling.
> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
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--
Paulo Zanoni
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