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From:   Kristian Kristensen <hoegsberg@google.com>
Date:   Thu, 30 Jul 2020 13:51:51 -0700
Message-ID: <CAOPc6T=+Yx=+QzOr+6f3SXZXPqE-FTKkis4a+pODnGM5pxyTVQ@mail.gmail.com>
Subject: Re: [v1] drm/msm/dpu: Fix scale params in plane validation
To:     Kalyan Thota <kalyan_t@codeaurora.org>
Cc:     DRI Development <dri-devel@lists.freedesktop.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        freedreno <freedreno@lists.freedesktop.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        Rob Clark <robdclark@gmail.com>,
        Sean Paul <seanpaul@chromium.org>,
        hoegsberg <hoegsberg@chromium.org>,
        Doug Anderson <dianders@chromium.org>, mkrishn@codeaurora.org,
        travitej@codeaurora.org, nganji@codeaurora.org
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On Thu, Jul 30, 2020 at 6:39 AM Kalyan Thota <kalyan_t@codeaurora.org> wrote:
>
> Plane validation uses an API drm_calc_scale which will
> return src/dst value as a scale ratio.
>
> when viewing the range on a scale the values should fall in as
>
> Upscale ratio < Unity scale < Downscale ratio for src/dst formula
>
> Fix the min and max scale ratios to suit the API accordingly.
>
> Signed-off-by: Kalyan Thota <kalyan_t@codeaurora.org>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> index 6379fe1..e46dcb9 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_plane.c
> @@ -946,9 +946,9 @@ static int dpu_plane_atomic_check(struct drm_plane *plane,
>                 crtc_state = drm_atomic_get_new_crtc_state(state->state,
>                                                            state->crtc);
>
> -       min_scale = FRAC_16_16(1, pdpu->pipe_sblk->maxdwnscale);
> +       min_scale = FRAC_16_16(1, pdpu->pipe_sblk->maxupscale);
>         ret = drm_atomic_helper_check_plane_state(state, crtc_state, min_scale,
> -                                         pdpu->pipe_sblk->maxupscale << 16,
> +                                         pdpu->pipe_sblk->maxdwnscale << 16,
>                                           true, true);
>         if (ret) {
>                 DPU_DEBUG_PLANE(pdpu, "Check plane state failed (%d)\n", ret);

Right, I can see how the drm convention of scaling factor being from
dest to src (ie 2x scaling up src to dst is as scale factor of 0.5).
Thanks for fixing this,

Tested-by: Kristian H. Kristensen <hoegsberg@google.com>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>

> --
> 1.9.1
>