linux-kernel - Re: [PATCH v8 22/23] drm/mediatek: Power on devices in OVL adaptor when atomic enable

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Message-ID: <691c1458eb5e45d8c14f24e78f47b2840f589ea7.camel@mediatek.com>
Date:   Wed, 18 Oct 2023 04:54:31 +0000
From:   Shawn Sung (宋孝謙) 
        <Shawn.Sung@...iatek.com>
To:     CK Hu (胡俊光) <ck.hu@...iatek.com>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        Yongqiang Niu (牛永强) 
        <yongqiang.niu@...iatek.com>,
        "chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>,
        Jason-JH Lin (林睿祥) 
        <Jason-JH.Lin@...iatek.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Moudy Ho (何宗原) <Moudy.Ho@...iatek.com>,
        Nancy Lin (林欣螢) <Nancy.Lin@...iatek.com>,
        "daniel@...ll.ch" <daniel@...ll.ch>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        "mchehab@...nel.org" <mchehab@...nel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Nathan Lu (呂東霖) <Nathan.Lu@...iatek.com>,
        "airlied@...il.com" <airlied@...il.com>,
        "sean@...rly.run" <sean@...rly.run>,
        "hverkuil-cisco@...all.nl" <hverkuil-cisco@...all.nl>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "fshao@...omium.org" <fshao@...omium.org>,
        "johnson.wang@...iatek.corp-partner.google.com" 
        <johnson.wang@...iatek.corp-partner.google.com>
Subject: Re: [PATCH v8 22/23] drm/mediatek: Power on devices in OVL adaptor
 when atomic enable

Hi CK,

On Wed, 2023-10-18 at 02:02 +0000, CK Hu (胡俊光) wrote:
> Hi, Hsiao-chien:
> 
> On Mon, 2023-10-16 at 18:40 +0800, Hsiao Chien Sung wrote:
> > Different from OVL, OVL adaptor is a pseudo device so we didn't
> > define it in the device tree, consequently,
> > pm_runtime_resume_and_get()
> > called by .atomic_enable() powers on no device in OVL adaptor and
> > leads to power outage in the corresponding IOMMU.
> > 
... snip ...
> > +int mtk_ovl_adaptor_power_on(struct device *dev)
> > +{
> > +	int i, ret;
> > +	struct mtk_disp_ovl_adaptor *ovl_adaptor =
> > dev_get_drvdata(dev);
> > +
> > +	for (i = 0; i < OVL_ADAPTOR_ID_MAX; i++) {
> > +		if (!ovl_adaptor->ovl_adaptor_comp[i] ||
> > +		    !comp_matches[i].funcs->power_on)
> > +			continue;
> 
> To simplify the code, you could call mtk_ddp_comp_power_on() for all
> sub device, and drop power_on()/power_off() of mdp_rdma.
> 
> Regards,
> CK
> 

Since ovl_adaptor_comp is a `struct device`, we can't reuse
mtk_ddp_comp_power_on() here. Had submited a new version (v9) and wrap
the power off procedure as a static inline function to reuse it.

Regards,
Shawn