linux-kernel - Re: [PATCH v4 13/78] drm/vc4: kms: Convert to for_each_new_crtc

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Message-ID: <CAPY8ntBpGsak=s8tOmmDA-2kE5mp6+TrqyK3930Ypm7Q9gcUJw@mail.gmail.com>
Date:   Wed, 29 Jul 2020 16:02:06 +0100
From:   Dave Stevenson <dave.stevenson@...pberrypi.com>
To:     Maxime Ripard <maxime@...no.tech>
Cc:     Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Eric Anholt <eric@...olt.net>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        linux-rpi-kernel@...ts.infradead.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-arm-kernel@...ts.infradead.org,
        LKML <linux-kernel@...r.kernel.org>,
        Tim Gover <tim.gover@...pberrypi.com>,
        Phil Elwell <phil@...pberrypi.com>
Subject: Re: [PATCH v4 13/78] drm/vc4: kms: Convert to for_each_new_crtc_state

Hi Maxime

On Wed, 8 Jul 2020 at 18:42, Maxime Ripard <maxime@...no.tech> wrote:
>
> The vc4 atomic commit loop has an handrolled loop that is basically
> identical to for_each_new_crtc_state, let's convert it to that helper.
>
> Signed-off-by: Maxime Ripard <maxime@...no.tech>
> ---
>  drivers/gpu/drm/vc4/vc4_kms.c |  9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
> index 210cc2408087..717673b18132 100644
> --- a/drivers/gpu/drm/vc4/vc4_kms.c
> +++ b/drivers/gpu/drm/vc4/vc4_kms.c
> @@ -152,14 +152,13 @@ vc4_atomic_complete_commit(struct drm_atomic_state *state)
>         struct drm_device *dev = state->dev;
>         struct vc4_dev *vc4 = to_vc4_dev(dev);
>         struct vc4_hvs *hvs = vc4->hvs;
> -       struct vc4_crtc *vc4_crtc;
> +       struct drm_crtc_state *new_crtc_state;
> +       struct drm_crtc *crtc;
>         int i;
>
> -       for (i = 0; i < dev->mode_config.num_crtc; i++) {
> -               if (!state->crtcs[i].ptr || !state->crtcs[i].commit)
> -                       continue;
> +       for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
> +               struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);

for_each_new_crtc_in_state doesn't check !state->crtcs[i].commit as
the hand rolled loop did. Sorry, this is my lack of knowledge, but
does that actually make any real difference?

I see nothing wrong in calling vc4_hvs_mask_underrun multiple times
anyway, so it's most likely going to be harmless anyway, but wanted to
query it.

  Dave

>
> -               vc4_crtc = to_vc4_crtc(state->crtcs[i].ptr);
>                 vc4_hvs_mask_underrun(dev, vc4_crtc->channel);
>         }
>
> --
> git-series 0.9.1