[igt-dev] [i-g-t] tests/kms_plane_alpha_blend: Align width to 256B

[Srinivas, Vidya]

> -----Original Message-----
> From: Juha-Pekka Heikkilä <juhapekka.heikkila at gmail.com>
> Sent: Tuesday, August 3, 2021 11:19 PM
> To: Srinivas, Vidya <vidya.srinivas at intel.com>
> Cc: Surendrakumar Upadhyay, TejaskumarX
> <tejaskumarx.surendrakumar.upadhyay at intel.com>; Sharma, Swati2
> <swati2.sharma at intel.com>; igt-dev at lists.freedesktop.org
> Subject: Re: [igt-dev] [i-g-t] tests/kms_plane_alpha_blend: Align width to
> 256B
> 
> On Tue, Aug 3, 2021 at 7:16 PM Srinivas, Vidya <vidya.srinivas at intel.com>
> wrote:
> >
> >
> >
> > > -----Original Message-----
> > > From: igt-dev <igt-dev-bounces at lists.freedesktop.org> On Behalf Of
> > > Juha- Pekka Heikkilä
> > > Sent: Tuesday, August 3, 2021 12:49 AM
> > > To: Surendrakumar Upadhyay, TejaskumarX
> > > <tejaskumarx.surendrakumar.upadhyay at intel.com>
> > > Cc: Sharma, Swati2 <swati2.sharma at intel.com>; igt-
> > > dev at lists.freedesktop.org
> > > Subject: Re: [igt-dev] [i-g-t] tests/kms_plane_alpha_blend: Align
> > > width to 256B
> > >
> > > On Mon, Aug 2, 2021 at 5:16 PM Surendrakumar Upadhyay, TejaskumarX
> > > <tejaskumarx.surendrakumar.upadhyay at intel.com> wrote:
> > > >
> > > > Hi JP,
> > > >
> > > > You are right i915 driver is giving 64B aligned buffer but test
> > > > uses raw width
> > > and thus it requires width to be aligned.
> > >
> > > Can you try this on the device which is failing:
> > > https://patchwork.freedesktop.org/series/93317/
> > >
> > > It will put on pixel blend and alpha and try different width linear
> > > fbs and compare results with crc. This should tell if alignments
> > > somehow can affect the crc on your test machine. On my ICL everything
> work as expected.
> > >
> >
> > Hi Juha-Pekka
> >
> > With your https://patchwork.freedesktop.org/series/93317/ the test
> PASSES.
> > But we need to use both planes and exact same sequence as
> > kms_plane_alpha_blend coverage-premultiplied-constant case to
> reproduce the issue.
> >
> > But with this modification (same as kms_plane_alpha_blend) done here
> > https://patchwork.freedesktop.org/patch/448369/?series=93317&rev=3
> > It PASS with ALIGN in draw_squares and draw_squares_coverage but fails
> without the ALIGNMENT.
> >
> > Kindly have a check. Thank you. Apologies, I pushed rev3 on top of yours to
> try-bot to maintain context.
> >
> 
> Hi Vidya,
> 
> thanks for showing this. Your change should segfault because with your
> alignment that memory drawing function will draw past reserved memory
> but that's not the interesting part. That original bug was included on the
> cut'n'pasted lines, it has nothing to do with strides but just simple rounding
> issue.
> 
> Where there's this function:
> 
> +static void draw_squares(struct igt_fb *fb, int w, int h, double a) {
> +cairo_t *cr = igt_get_cairo_ctx(fb->fd, fb);
> +
> + cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
> + igt_paint_color_alpha(cr, 0, 0, w / 2, h / 2, 1., 0., 0., a);
> + igt_paint_color_alpha(cr, w / 2, 0, w / 2, h / 2, 0., 1., 0., a);
> + igt_paint_color_alpha(cr, 0, h / 2, w / 2, h / 2, 0., 0., 1., a);
> + igt_paint_color_alpha(cr, w / 2, h / 2, w / 4, h / 2, 1., 1., 1., a);
> + igt_paint_color_alpha(cr, 3 * w / 4, h / 2, w / 4, h / 2, 0., 0., 0.,
> + a);
> +
> + igt_put_cairo_ctx(cr);
> +}
> 
> 
> That last igt_paint_color_alpha(..) will need to say:
> 
> igt_paint_color_alpha(cr, w * 3 / 4, h / 2, w - (w * 3 / 4), h / 2, 0., 0., 0., a);
> 
> Otherwise it can draw one pixel too narrow box.

Hello Juha-Pekka,

Thank you so much. With this line change this test kms_stridetest_crc and the kms_plane_alpha_blend works too.
No alignment is needed. Sorry, somehow it did not give the CRASH.
This is the same issue I was seeking your help, where we tried multiple fixes.
Thank you so very much. I have submitted the fix you provided in your name
https://patchwork.freedesktop.org/patch/448556/?series=93370&rev=1

https://patchwork.freedesktop.org/series/93370/
@Surendrakumar Upadhyay, TejaskumarX Apologies, I have submitted the revert in the same series.
Thank you Tejas.

Can you kindly help review and merge the same?

Regards
Vidya

> 
> /Juha-Pekka
> 
> > >
> > > >
> > > > Thanks,
> > > > Tejas
> > > >
> > > > > -----Original Message-----
> > > > > From: Sharma, Swati2 <swati2.sharma at intel.com>
> > > > > Sent: 02 August 2021 18:35
> > > > > To: juhapekka.heikkila at gmail.com; Surendrakumar Upadhyay,
> > > > > TejaskumarX <tejaskumarx.surendrakumar.upadhyay at intel.com>;
> igt-
> > > > > dev at lists.freedesktop.org
> > > > > Subject: Re: [igt-dev] [i-g-t] tests/kms_plane_alpha_blend:
> > > > > Align width to 256B
> > > > >
> > > > > Hi JP,
> > > > >
> > > > > Tejas reapplied the same fix as in
> > > > > https://patchwork.freedesktop.org/patch/445010/?series=92751&rev
> > > > > =2
> > > > > which was reviewed by Daniel.
> > > > >
> > > > > On 02-Aug-21 5:42 PM, Juha-Pekka Heikkila wrote:
> > > > > > Hi Tejas, Swati,
> > > > > >
> > > > > > I was confused when I read this patch, mind you tell what happen
> here?
> > > > > > To me it look like nothing matches with each other with the patch.
> > > > > >
> > > > > > Even subject is telling other things than what this patch actually
> does.
> > > > > >
> > > > > > On 30.7.2021 8.50, Sharma, Swati2 wrote:
> > > > > >> Reviewed-by:
> > > > > >> Swati Sharma <swati2.sharma at intel.com>
> > > > > >>
> > > > > >> On 28-Jul-21 10:25 AM, Tejas Upadhyay wrote:
> > > > > >>> some display resolutions like 1366x768 6bpc which does not
> > > > > >>> have 64B aligned width are creating crc mismatch in
> > > > > >>> kms_plane_alpha_blend test on Intel platforms.
> > > > > >
> > > > > > hm. You are saying none of Intel hw is able to show 1366 wide
> > > > > > framebuffers correctly? And it is fixed by hiding it from being tested?
> > > > > >
> > > > > > Memory given from kernel will have 64B alignment. You can
> > > > > > easily see by yourself.
> > > > > >
> > > > > >>>
> > > > > >>> Also having different alignment requirement by different
> > > > > >>> drivers, 256B aligned width should work for all drm drivers.
> > > > > >
> > > > > > You are saying you are fixing some problem with Intel hw, what
> > > > > > does all this other stuff have to do with it? None of those
> > > > > > other drivers are able to show 1366 pixels wide framebuffers either?
> > > > > >
> > > > > >>>
> > > > > >>> amdgpu and radeon, amdgpu_align_pitch: 256B armada,
> > > armada_pitch:
> > > > > >>> 128B
> > > > > >>> exynos_drm_gem_dumb_create: No alignment required
> > > > > >>> drm_gem_shmem_dumb_create: 8B
> > > > > >>> drm_gem_vram_fill_create_dumb: 8B
> > > > > >>>
> > > > > >>> Thus 256B covers everything we see in the kernel drm drivers.
> > > > > >>> Signed-off-by: Tejas Upadhyay
> > > > > >>> <tejaskumarx.surendrakumar.upadhyay at intel.com>
> > > > > >>> ---
> > > > > >>>   tests/kms_plane_alpha_blend.c | 1 +
> > > > > >>>   1 file changed, 1 insertion(+)
> > > > > >>>
> > > > > >>> diff --git a/tests/kms_plane_alpha_blend.c
> > > > > >>> b/tests/kms_plane_alpha_blend.c index d649a09f..864e83f9
> > > > > >>> 100644
> > > > > >>> --- a/tests/kms_plane_alpha_blend.c
> > > > > >>> +++ b/tests/kms_plane_alpha_blend.c
> > > > > >>> @@ -168,6 +168,7 @@ static void prepare_crtc(data_t *data,
> > > > > >>> igt_output_t *output, enum pipe pipe)
> > > > > >>>       w = mode->hdisplay;
> > > > > >>>       h = mode->vdisplay;
> > > > > >>> +    w = ALIGN(w, 256);
> > > > > >
> > > > > > This doesn't cause anything to align with 256 bytes. This
> > > > > > makes fb width in pixels divisible by 256. For anything to do
> > > > > > with fb alignments..this has very little to do. Kernel will do
> > > > > > viewport clipping hence for actual intended test this does
> > > > > > nothing. FB alignments are handled otherwise as in this case
> > > > > > with with linear fb will
> > > > > have 64 bytes per stride.
> > > > > >
> > > > > >>>       /* recreate all fbs if incompatible */
> > > > > >>>       if (data->xrgb_fb.width != w || data->xrgb_fb.height != h) {
> > > > > >>>           cairo_t *cr;
> > > > > >>>
> > > > > >>
> > > > > >
> > > > > > If this patch actually fixed anything you'll need to create hw
> > > > > > wa and this need to be fixed in kernel. Not testing is not fixing.
> > > > > > Imo there should be no problem for Intel hw to show varying fb
> > > > > > sizes, including
> > > > > > 1366 wide.
> > > > > >
> > > > > > /Juha-Pekka
> > > > >
> > > > > --
> > > > > ~Swati Sharma