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

From: "Shawn Sung (宋孝謙)" <Shawn.Sung@mediatek.com>
To: "CK Hu (胡俊光)" <ck.hu@mediatek.com>,
	"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
	"angelogioacchino.delregno@collabora.com"
	<angelogioacchino.delregno@collabora.com>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	"krzysztof.kozlowski+dt@linaro.org"
	<krzysztof.kozlowski+dt@linaro.org>
Cc: "Yongqiang Niu (牛永强)" <yongqiang.niu@mediatek.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mediatek@lists.infradead.org"
	<linux-mediatek@lists.infradead.org>,
	"chunkuang.hu@kernel.org" <chunkuang.hu@kernel.org>,
	"Jason-JH Lin (林睿祥)" <Jason-JH.Lin@mediatek.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"Nancy Lin (林欣螢)" <Nancy.Lin@mediatek.com>,
	"Moudy Ho (何宗原)" <Moudy.Ho@mediatek.com>,
	"daniel@ffwll.ch" <daniel@ffwll.ch>,
	"p.zabel@pengutronix.de" <p.zabel@pengutronix.de>,
	"mchehab@kernel.org" <mchehab@kernel.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"Nathan Lu (呂東霖)" <Nathan.Lu@mediatek.com>,
	"airlied@gmail.com" <airlied@gmail.com>,
	"sean@poorly.run" <sean@poorly.run>,
	"hverkuil-cisco@xs4all.nl" <hverkuil-cisco@xs4all.nl>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"fshao@chromium.org" <fshao@chromium.org>,
	"johnson.wang@mediatek.corp-partner.google.com"
	<johnson.wang@mediatek.corp-partner.google.com>
Subject: Re: [PATCH v8 22/23] drm/mediatek: Power on devices in OVL adaptor when atomic enable
Date: Tue, 17 Oct 2023 11:04:28 +0000	[thread overview]
Message-ID: <63f9b96208e0b0b25da843f6aa0c7e0dd7f8e0bf.camel@mediatek.com> (raw)
In-Reply-To: <fef1cae9-057c-4946-b9d3-27a799fefc5d@collabora.com>

Hi Angelo,

On Tue, 2023-10-17 at 11:54 +0200, AngeloGioacchino Del Regno wrote:
> Il 16/10/23 12:40, Hsiao Chien Sung ha scritto:
> > 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.
> > 
> > To resolve the issue, we implement a function to power on the RDMAs
> > in OVL adaptor, and the system will make sure the IOMMU is powered
> > on
> > as well because of the device link (iommus) in the RDMA nodes in
> > DTS.
> > 
> > Fixes: 5db12f5d843b ("media: drm/mediatek: Add pm runtime support
> > for ovl and rdma")
> > 
> > Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com>
> > ---
> >   drivers/gpu/drm/mediatek/mtk_disp_drv.h       |  4 ++
> >   .../gpu/drm/mediatek/mtk_disp_ovl_adaptor.c   | 62
> > +++++++++++++++++++
> >   drivers/gpu/drm/mediatek/mtk_drm_crtc.c       | 28 +++------
> >   drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c   |  2 +
> >   drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h   | 20 ++++++
> >   drivers/gpu/drm/mediatek/mtk_mdp_rdma.c       | 16 +++++
> >   6 files changed, 111 insertions(+), 21 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_disp_drv.h
> > b/drivers/gpu/drm/mediatek/mtk_disp_drv.h
> > index e2b602037ac3..c44f5b31bab5 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_disp_drv.h
> > +++ b/drivers/gpu/drm/mediatek/mtk_disp_drv.h
> > @@ -109,6 +109,8 @@ void mtk_ovl_adaptor_connect(struct device
> > *dev, struct device *mmsys_dev,
> >   			     unsigned int next);
> >   void mtk_ovl_adaptor_disconnect(struct device *dev, struct device
> > *mmsys_dev,
> >   				unsigned int next);
> > +int mtk_ovl_adaptor_power_on(struct device *dev);
> > +void mtk_ovl_adaptor_power_off(struct device *dev);
> >   int mtk_ovl_adaptor_clk_enable(struct device *dev);
> >   void mtk_ovl_adaptor_clk_disable(struct device *dev);
> >   void mtk_ovl_adaptor_config(struct device *dev, unsigned int w,
> > @@ -150,6 +152,8 @@ void mtk_rdma_disable_vblank(struct device
> > *dev);
> >   const u32 *mtk_rdma_get_formats(struct device *dev);
> >   size_t mtk_rdma_get_num_formats(struct device *dev);
> >   
> > +int mtk_mdp_rdma_power_on(struct device *dev);
> > +void mtk_mdp_rdma_power_off(struct device *dev);
> >   int mtk_mdp_rdma_clk_enable(struct device *dev);
> >   void mtk_mdp_rdma_clk_disable(struct device *dev);
> >   void mtk_mdp_rdma_start(struct device *dev, struct cmdq_pkt
> > *cmdq_pkt);
> > diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> > b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> > index b80425360e76..8de57a5f5518 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl_adaptor.c
> > @@ -98,6 +98,8 @@ static const struct mtk_ddp_comp_funcs _padding =
> > {
> >   };
> >   
> >   static const struct mtk_ddp_comp_funcs _rdma = {
> > +	.power_on = mtk_mdp_rdma_power_on,
> > +	.power_off = mtk_mdp_rdma_power_off,
> >   	.clk_enable = mtk_mdp_rdma_clk_enable,
> >   	.clk_disable = mtk_mdp_rdma_clk_disable,
> >   };
> > @@ -241,6 +243,66 @@ void mtk_ovl_adaptor_stop(struct device *dev)
> >   	}
> >   }
> >   
> > +/**
> > + * mtk_ovl_adaptor_power_on - Power on devices in OVL adaptor
> > + * @dev: device to be powered on
> > + *
> > + * Different from OVL, OVL adaptor is a pseudo device so
> > + * we didn't define it in the device tree,
> > pm_runtime_resume_and_get()
> > + * called by .atomic_enable() power on no device in OVL adaptor,
> > + * we have to implement a function to do the job instead.
> > + *
> > + * returns:
> > + * zero on success, errno on failures.
> 
> You're almost there! There's just one mistake making this invalid
> kerneldoc;
> change to...
> 
>   * Return: Zero for success or negative number for failure.
> 
> 
https://urldefense.com/v3/__https://docs.kernel.org/doc-guide/kernel-doc.html__;!!CTRNKA9wMg0ARbw!kAfpT6aSoiHbv1EviMygmToxfzcWTHgbJ13w--JKWitq0e_Im6koKGFFXnCt_ZZ_BD4IoqqG9vuBBU20M8gW0hTHyG_mh7qX$
>  

Thank you for pointing this out and giving an example.
Will change this in the next version.

> > +/**
> > + * mtk_ovl_adaptor_power_off - Power off devices in OVL adaptor
> > + * @dev: device to be powered off
> > + *
> > + * call .power_off() function if defined
> 
>   * Calls the .power_off() ovl_adaptor component callback if it is
> present.
> 
> > + */
> 
> Regards,
> Angelo
> 

Got it, will modify it in the next version.

Thanks,
Shawn