Re: [PATCH v2 02/12] iommu/mediatek: Add probe_defer for smi-larb

From: Yong Wu <yong.wu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
To: Matthias Brugger <matthias.bgg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: youlin.pei-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org,
	devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Nicolas Boichat
	<drinkcat-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
	srv_heupstream-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org,
	Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Evan Green <evgreen-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
	Tomasz Figa <tfiga-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	linux-mediatek-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	yingjoe.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org,
	anan.sun-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org,
	Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [PATCH v2 02/12] iommu/mediatek: Add probe_defer for smi-larb
Date: Sat, 22 Jun 2019 10:42:47 +0800	[thread overview]
Message-ID: <1561171367.4850.8.camel@mhfsdcap03> (raw)
In-Reply-To: <a11fa818-cf62-cc24-2c41-4688fda5a88f-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>

On Wed, 2019-06-19 at 15:52 +0200, Matthias Brugger wrote:
> 
> On 10/06/2019 14:55, Yong Wu wrote:
> > 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 consumer always is 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.
> > 
> > This is a preparing patch for adding device_link.
> > 
> > Signed-off-by: Yong Wu <yong.wu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
> > ---
> >  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 6fe3369..f7599d8 100644
> > --- a/drivers/iommu/mtk_iommu.c
> > +++ b/drivers/iommu/mtk_iommu.c
> > @@ -664,7 +664,7 @@ 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) {
> 
> can't we use:
> device_lock()
> device_is_bound(struct device *dev)
> device_unlock()

A new API for me. Thanks the hint. I have tried. it is ok.

> 
> >  			of_node_put(larbnode);
> >  			return -EPROBE_DEFER;
> >  		}
> > diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
> > index 0b0908c..c43c4a0 100644
> > --- a/drivers/iommu/mtk_iommu_v1.c
> > +++ b/drivers/iommu/mtk_iommu_v1.c
> > @@ -604,7 +604,7 @@ static int mtk_iommu_probe(struct platform_device *pdev)
> >  			plarbdev = of_platform_device_create(
> >  						larb_spec.np, NULL,
> >  						platform_bus_type.dev_root);
> > -			if (!plarbdev) {
> > +			if (!plarbdev || !plarbdev->dev.driver) {
> >  				of_node_put(larb_spec.np);
> >  				return -EPROBE_DEFER;
> >  			}
> > 