linux-kernel - Re: [RFC PATCH 7/9] drm/rockchip: force enable vop when do mode setting

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Date:	Wed, 2 Dec 2015 17:55:36 +0100
From:	Thierry Reding <thierry.reding@...il.com>
To:	Mark Yao <mark.yao@...k-chips.com>
Cc:	David Airlie <airlied@...ux.ie>, Heiko Stuebner <heiko@...ech.de>,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 7/9] drm/rockchip: force enable vop when do mode
 setting

On Tue, Dec 01, 2015 at 11:32:01AM +0800, Mark Yao wrote:
> When do mode setting, mean that we want to enable display output,
> but sometimes, vop_crtc_enable is after mode_set, we can't allow
> that, so force enable vop in mode setting.
> 
> Signed-off-by: Mark Yao <mark.yao@...k-chips.com>
> ---
>  drivers/gpu/drm/rockchip/rockchip_drm_vop.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> index c65b454..7c07537 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> @@ -1110,6 +1110,7 @@ static void vop_crtc_mode_set_nofb(struct drm_crtc *crtc)
>  	u16 vact_end = vact_st + vdisplay;
>  	uint32_t val;
>  
> +	vop_crtc_enable(crtc);
>  	/*
>  	 * If dclk rate is zero, mean that scanout is stop,
>  	 * we don't need wait any more.

Have you considered simply moving everything into ->enable()? That's
what I did for Tegra, for much the same reasons that you gave in the
commit message. Doing so gives you a much simpler call graph. Really
the only thing you need to do is move around the code, and perhaps a
different way to get ahold of the display mode, but you can use the
Tegra driver as a reference for how to do that.

Thierry

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