linux-kernel - Re: [PATCH v10 15/24] drm/mediatek: Remove ineffectual power management codes

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Message-ID: <b606d465335db31235d9472d71c498eea10c3726.camel@mediatek.com>
Date:   Tue, 24 Oct 2023 09:39:48 +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>,
        Jason-JH Lin (林睿祥) 
        <Jason-JH.Lin@...iatek.com>,
        "chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>,
        "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>,
        "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>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "sean@...rly.run" <sean@...rly.run>,
        "johnson.wang@...iatek.corp-partner.google.com" 
        <johnson.wang@...iatek.corp-partner.google.com>
Subject: Re: [PATCH v10 15/24] drm/mediatek: Remove ineffectual power
 management codes

Hi CK,

On Tue, 2023-10-24 at 09:25 +0000, CK Hu (胡俊光) wrote:
> Hi, Hsiao-chien:
> 
> On Thu, 2023-10-19 at 13:56 +0800, Hsiao Chien Sung wrote:
> > Display modules will be powered on when .atomic_enable(),
> > there is no need to do it again in mtk_crtc_ddp_hw_init().
> > Besides, the DRM devices are created manually when mtk-mmsys
> > is probed and there is no power domain linked to it.
> > 
> > Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC
> > MT8173.")
> > 
> > Signed-off-by: Hsiao Chien Sung <shawn.sung@...iatek.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 18 +++---------------
> >  1 file changed, 3 insertions(+), 15 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > index bc4cc75cca18..c7edd80be428 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> > @@ -6,7 +6,6 @@
> >  #include <linux/clk.h>
> >  #include <linux/dma-mapping.h>
> >  #include <linux/mailbox_controller.h>
> > -#include <linux/pm_runtime.h>
> >  #include <linux/soc/mediatek/mtk-cmdq.h>
> >  #include <linux/soc/mediatek/mtk-mmsys.h>
> >  #include <linux/soc/mediatek/mtk-mutex.h>
> > @@ -362,22 +361,16 @@ static int mtk_crtc_ddp_hw_init(struct
> > mtk_drm_crtc *mtk_crtc, struct drm_atomic
> >  		drm_connector_list_iter_end(&conn_iter);
> >  	}
> >  
> > -	ret = pm_runtime_resume_and_get(crtc->dev->dev);
> 
> crtc->dev->dev is mmsys device. In mt8173.dtsi, you could find that
> mmsys has its own power. So I think we should keep this.
> 
> Regards,
> CK

Didn't notice this difference in the dts, thank you for checking.
Will remove this patch in the next version.

Thanks,
Shawn