Re: [RFC 2/3] drm/mediatek: add support for Mediatek SoC MT2701

CK Hu
2016-05-13T03:59:27Z

Hi, YT:

On Thu, 2016-05-12 at 19:49 +0800, yt.shen@mediatek.com wrote:
> From: YT Shen <yt.shen@mediatek.com>
>
> This patch add support for the Mediatek MT2701 DISP subsystem.
> There is only one OVL engine in MT2701, and we have shadow
> register support here.
>
> Signed-off-by: YT Shen <yt.shen@mediatek.com>
> ---

> @@ -385,12 +422,16 @@ static void mtk_drm_crtc_atomic_begin(struct drm_crtc *crtc,
> mtk_crtc->event = state->base.event;
> state->base.event = NULL;
> }
> +
> + if (priv->data->shadow_register)
> + mtk_disp_mutex_acquire(mtk_crtc->mutex);
> }
>
> @@ -409,6 +450,11 @@ static void mtk_drm_crtc_atomic_flush(struct drm_crtc *crtc,
> }
> if (pending_planes)
> mtk_crtc->pending_planes = true;
> +
> + if (priv->data->shadow_register) {
> + mtk_crtc_ddp_config(crtc);
> + mtk_disp_mutex_release(mtk_crtc->mutex);
> + }
> }
>

I think it's better to call mtk_disp_mutex_acquire() and
mtk_disp_mutex_release() as near as possible to prevent mutex locked for
a long time. All HW register access of this atomic setting is in
mtk_crtc_ddp_config(), so it's better to move mtk_disp_mutex_acquire()
just before mtk_crtc_ddp_config().

Regards,
CK