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From: Yong Wu <yong.wu@mediatek.com>
To: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Joerg Roedel <joro@8bytes.org>, Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
	David Airlie <airlied@linux.ie>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>
Cc: Evan Green <evgreen@chromium.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Tomasz Figa <tfiga@chromium.org>,
	Will Deacon <will.deacon@arm.com>,
	<linux-mediatek@lists.infradead.org>,
	<srv_heupstream@mediatek.com>, <devicetree@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<iommu@lists.linux-foundation.org>, <youlin.pei@mediatek.com>,
	Matthias Kaehlcke <mka@chromium.org>, <anan.sun@mediatek.com>,
	<yi.kuo@mediatek.com>, <acourbot@chromium.org>,
	<linux-media@vger.kernel.org>, <dri-devel@lists.freedesktop.org>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	Chun-Kuang Hu <chunkuang.hu@kernel.org>,
	"Philipp Zabel" <p.zabel@pengutronix.de>,
	Tiffany Lin <tiffany.lin@mediatek.com>,
	Hsin-Yi Wang <hsinyi@chromium.org>,
	Eizan Miyamoto <eizan@chromium.org>, <anthony.huang@mediatek.com>,
	Frank Wunderlich <frank-w@public-files.de>
Subject: Re: [PATCH v8 03/12] iommu/mediatek: Add probe_defer for smi-larb
Date: Thu, 30 Sep 2021 15:14:45 +0800	[thread overview]
Message-ID: <d3ed2bdef81ce1822b20da9570b5245cc0df6330.camel@mediatek.com> (raw)
In-Reply-To: <33a8b313-ad1b-d307-7e8c-2fdebdc6f1a7@collabora.com>

On Wed, 2021-09-29 at 18:33 +0200, Dafna Hirschfeld wrote:
> 
> On 29.09.21 03:37, Yong Wu wrote:
> > Prepare for adding device_link.
> > 
> > The iommu consumer should use device_link to connect with the
> > smi-larb(supplier). then the smi-larb should run before the iommu
> > consumer. Here we delay the iommu driver until the smi driver is
> > ready,
> > then all the iommu consumers always are after the smi driver.
> > 
> > When there is no this patch, if some consumer drivers run before
> > smi-larb, the supplier link_status is DL_DEV_NO_DRIVER(0) in the
> > device_link_add, then device_links_driver_bound will use WARN_ON
> > to complain that the link_status of supplier is not right.
> > 
> > device_is_bound may be more elegant here. but it is not allowed to
> > EXPORT from https://lore.kernel.org/patchwork/patch/1334670/.
> > 
> > Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> > Tested-by: Frank Wunderlich <frank-w@public-files.de> # BPI-
> > R2/MT7623
> > ---
> >   drivers/iommu/mtk_iommu.c    | 2 +-
> >   drivers/iommu/mtk_iommu_v1.c | 2 +-
> >   2 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> > index d837adfd1da5..d5848f78a677 100644
> > --- a/drivers/iommu/mtk_iommu.c
> > +++ b/drivers/iommu/mtk_iommu.c
> > @@ -844,7 +844,7 @@ static int mtk_iommu_probe(struct
> > platform_device *pdev)
> >   			id = i;
> >   
> >   		plarbdev = of_find_device_by_node(larbnode);
> > -		if (!plarbdev) {
> > +		if (!plarbdev || !plarbdev->dev.driver) {
> >   			of_node_put(larbnode);
> >   			return -EPROBE_DEFER;
> 
> if plarbdev is null doesn't that mean that the device does not exist?

This is probe function, Is it possible the platform device is not ready
at this time?

I checked the platform device should be created at:

of_platform_default_populate_init:  arch_initcall_sync
  ->of_platform_populate
      ->of_platform_device_create_pdata

Not sure if this may be delayed for some device. If not, it should be
ENODEV here.

> so we should return -ENODEV in that case?
> 
> thanks,
> Dafna
> 
> >   		}
> > diff --git a/drivers/iommu/mtk_iommu_v1.c
> > b/drivers/iommu/mtk_iommu_v1.c
> > index 1467ba1e4417..4d7809432239 100644
> > --- a/drivers/iommu/mtk_iommu_v1.c
> > +++ b/drivers/iommu/mtk_iommu_v1.c
> > @@ -602,7 +602,7 @@ static int mtk_iommu_probe(struct
> > platform_device *pdev)
> >   		}
> >   
> >   		plarbdev = of_find_device_by_node(larbnode);
> > -		if (!plarbdev) {
> > +		if (!plarbdev || !plarbdev->dev.driver) {
> >   			of_node_put(larbnode);
> >   			return -EPROBE_DEFER;
> >   		}
> > 
> 
> _______________________________________________
> Linux-mediatek mailing list
> Linux-mediatek@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-mediatek

  reply	other threads:[~2021-09-30  7:14 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-29  1:37 [PATCH v8 00/12] Clean up "mediatek,larb" Yong Wu
2021-09-29  1:37 ` [PATCH v8 01/12] dt-binding: mediatek: Get rid of mediatek, larb for multimedia HW Yong Wu
2021-09-29  1:37 ` [PATCH v8 02/12] iommu/mediatek-v1: Free the existed fwspec if the master dev already has Yong Wu
2021-09-29  1:37 ` [PATCH v8 03/12] iommu/mediatek: Add probe_defer for smi-larb Yong Wu
2021-09-29 16:33   ` Dafna Hirschfeld
2021-09-30  7:14     ` Yong Wu [this message]
2021-09-29  1:37 ` [PATCH v8 04/12] iommu/mediatek: Add device_link between the consumer and the larb devices Yong Wu
2021-10-11 12:36   ` Dafna Hirschfeld
2021-10-16  2:23     ` Yong Wu
2021-10-18  7:13       ` Dafna Hirschfeld
2021-10-25  3:57         ` Yong Wu
2021-09-29  1:37 ` [PATCH v8 05/12] media: mtk-jpeg: Get rid of mtk_smi_larb_get/put Yong Wu
2021-09-29  1:37 ` [PATCH v8 06/12] media: mtk-mdp: " Yong Wu
2021-09-29  1:37 ` [PATCH v8 07/12] drm/mediatek: Add pm runtime support for ovl and rdma Yong Wu
2021-09-29  1:37 ` [PATCH v8 08/12] drm/mediatek: Get rid of mtk_smi_larb_get/put Yong Wu
2021-09-29  1:37 ` [PATCH v8 09/12] media: mtk-vcodec: " Yong Wu
2021-09-29 12:13   ` Dafna Hirschfeld
2021-09-30  3:28     ` Yong Wu
2021-09-30 10:57       ` Dafna Hirschfeld
2021-10-07  2:57         ` Yong Wu
2021-09-29  1:37 ` [PATCH v8 10/12] memory: mtk-smi: " Yong Wu
2021-09-29  1:37 ` [PATCH v8 11/12] arm: dts: mediatek: Get rid of mediatek,larb for MM nodes Yong Wu
2021-09-29  1:37 ` [PATCH v8 12/12] arm64: " Yong Wu

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