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

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Date:   Tue, 24 Oct 2023 09:25:29 +0000
From:   CK Hu (胡俊光) <ck.hu@...iatek.com>
To:     Shawn Sung (宋孝謙) 
        <Shawn.Sung@...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>,
        "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>,
        "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, 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

> -	if (ret < 0) {
> -		DRM_ERROR("Failed to enable power domain: %d\n", ret);
> -		return ret;
> -	}
> -
>  	ret = mtk_mutex_prepare(mtk_crtc->mutex);
>  	if (ret < 0) {
>  		DRM_ERROR("Failed to enable mutex clock: %d\n", ret);
> -		goto err_pm_runtime_put;
> +		goto error;
>  	}
>  
>  	ret = mtk_crtc_ddp_clk_enable(mtk_crtc);
>  	if (ret < 0) {
>  		DRM_ERROR("Failed to enable component clocks: %d\n",
> ret);
> -		goto err_mutex_unprepare;
> +		goto error;
>  	}
>  
>  	for (i = 0; i < mtk_crtc->ddp_comp_nr - 1; i++) {
> @@ -426,16 +419,13 @@ static int mtk_crtc_ddp_hw_init(struct
> mtk_drm_crtc *mtk_crtc, struct drm_atomic
>  
>  	return 0;
>  
> -err_mutex_unprepare:
> +error:
>  	mtk_mutex_unprepare(mtk_crtc->mutex);
> -err_pm_runtime_put:
> -	pm_runtime_put(crtc->dev->dev);
>  	return ret;
>  }
>  
>  static void mtk_crtc_ddp_hw_fini(struct mtk_drm_crtc *mtk_crtc)
>  {
> -	struct drm_device *drm = mtk_crtc->base.dev;
>  	struct drm_crtc *crtc = &mtk_crtc->base;
>  	int i;
>  
> @@ -465,8 +455,6 @@ static void mtk_crtc_ddp_hw_fini(struct
> mtk_drm_crtc *mtk_crtc)
>  	mtk_crtc_ddp_clk_disable(mtk_crtc);
>  	mtk_mutex_unprepare(mtk_crtc->mutex);
>  
> -	pm_runtime_put(drm->dev);
> -
>  	if (crtc->state->event && !crtc->state->active) {
>  		spin_lock_irq(&crtc->dev->event_lock);
>  		drm_crtc_send_vblank_event(crtc, crtc->state->event);