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

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Date:	Thu, 03 Dec 2015 09:54:56 +0800
From:	Mark yao <mark.yao@...k-chips.com>
To:	Thierry Reding <thierry.reding@...il.com>,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	linux-rockchip@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC PATCH 7/9] drm/rockchip: force enable vop when do mode setting

On 2015年12月03日 06:17, Daniel Vetter wrote:
> On Wed, Dec 02, 2015 at 05:55:36PM +0100, Thierry Reding wrote:
>> 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.
> Yeah if writing mode related registers requires the thing to be on on your
> hw then you can't use the ->mode_set hooks. Those are explicitly called
> when everything is off (not just sometimes, at least with atomic helpers).
>
> Like Thierry said the recommendation is to just shovel that code into
> ->enable hooks. ->mode_set_nofb is mostly there to support easier
> transition for drivers which started with the legacy crtc helpers.
> -Daniel

Good, thanks, actually it solve my confusion.

-- 
Ｍark Yao


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