Re: [PATCH v6 7/9] media: mtk-mdp: use mdp-rdma0 alias to point to MDP master

[houlong wei]

On Mon, 2021-08-16 at 11:00 +0800, houlong wei wrote:
> On Mon, 2021-08-02 at 20:12 +0800, Eizan Miyamoto wrote:
> > ... Instead of depending on the presence of a mediatek,vpu property
> > in
> > the device node.
> > 
> > That property was originally added to link to the vpu node so that
> > the
> > mtk_mdp_core driver could pass the right device to
> > vpu_wdt_reg_handler(). However in a previous patch in this series,
> > the driver has been modified to search the device tree for that
> > node
> > instead.
> > 
> > That property was also used to indicate the primary MDP device, so
> > that
> > it can be passed to the V4L2 subsystem as well as register it to be
> > used when setting up queues in the open() callback for the
> > filesystem
> > device node that is created. In this case, assuming that the
> > primary
> > MDP device is the one with a specific alias seems useable because
> > the
> > alternative is to add a property to the device tree which doesn't
> > actually represent any facet of hardware (i.e., this being the
> > primary
> > MDP device is a software decision). In other words, this solution
> > is
> > equally as arbitrary, but at least it doesn't add a property to a
> > device node where said property is unrelated to the hardware
> > present.
> > 
> > Signed-off-by: Eizan Miyamoto <eizan@xxxxxxxxxxxx>
> > ---
> > 
> > (no changes since v1)
> > 
> >  drivers/media/platform/mtk-mdp/mtk_mdp_comp.c | 56 +++++++++++++--
> > ----
> >  drivers/media/platform/mtk-mdp/mtk_mdp_core.c | 36 ++++++++----
> >  2 files changed, 64 insertions(+), 28 deletions(-)
> > 
> > diff --git a/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
> > b/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
> > index 85ef274841a3..9527649de98e 100644
> > --- a/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
> > +++ b/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
> > @@ -151,29 +151,50 @@ void mtk_mdp_comp_clock_off(struct
> > mtk_mdp_comp
> > *comp)
> >  		mtk_smi_larb_put(comp->larb_dev);
> >  }
> >  
> > -static int mtk_mdp_comp_bind(struct device *dev, struct device
> > *master, void *data)
> > +/*
> > + * The MDP master device node is identified by the device tree
> > alias
> > + * "mdp-rdma0".
> > + */
> > +static bool is_mdp_master(struct device *dev)
> > +{
> > +	struct device_node *aliases, *mdp_rdma0_node;
> > +	const char *mdp_rdma0_path;
> > +
> > +	if (!dev->of_node)
> > +		return false;
> > +
> > +	aliases = of_find_node_by_path("/aliases");
> > +	if (!aliases) {
> > +		dev_err(dev, "no aliases found for mdp-rdma0");
> > +		return false;
> > +	}
> > +
> > +	mdp_rdma0_path = of_get_property(aliases, "mdp-rdma0", NULL);
> > +	if (!mdp_rdma0_path) {
> > +		dev_err(dev, "get mdp-rdma0 property of /aliases
> > failed");
> > +		return false;
> > +	}
> > +
> > +	mdp_rdma0_node = of_find_node_by_path(mdp_rdma0_path);
> > +	if (!mdp_rdma0_node) {
> > +		dev_err(dev, "path resolution failed for %s",
> > mdp_rdma0_path);
> > +		return false;
> > +	}
> > +
> 
> Hi Eizan,
> 
> "mdp-rdma0" may be not the only one master device node. In fact,
> there
> are 2 "mdp-rdma" in mt8173. You can see "mdp_rdma1" via below link.
> 
> 
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/arch/arm64/boot/dts/mediatek/mt8173.dtsi?h=v5.13.11#n1016
> If we add "mediatek,mt8173-mdp" to "mdp_rdma1" like below, we will
> have
> one more V4L2 video devie node.
> 
> 		mdp_rdma1: rdma@14002000 {
> 			compatible = "mediatek,mt8173-mdp-rdma",
> 				     "mediatek,mt8173-mdp";
> 			...
> 		}
> 
> We should consider the case that there are more than one "MDP_RDMA"
> components. 
> 
> Regards,
> Houlong
> 
> > +	return dev->of_node == mdp_rdma0_node;
> > +}
> > +
> > +static int mtk_mdp_comp_bind(struct device *dev, struct device
> > *master,
> > +			void *data)
> >  {
> >  	struct mtk_mdp_comp *comp = dev_get_drvdata(dev);
> >  	struct mtk_mdp_dev *mdp = data;
> > -	struct device_node *vpu_node;
> >  
> >  	mtk_mdp_register_component(mdp, comp);
> >  
> > -	/*
> > -	 * If this component has a "mediatek-vpu" property, it is
> > responsible for
> > -	 * notifying the mdp master driver about it so it can be
> > further initialized
> > -	 * later.
> > -	 */
> > -	vpu_node = of_parse_phandle(dev->of_node, "mediatek,vpu", 0);
> > -	if (vpu_node) {
> > +	if (is_mdp_master(dev)) {
> >  		int ret;
> >  
> > -		mdp->vpu_dev = of_find_device_by_node(vpu_node);
> > -		if (WARN_ON(!mdp->vpu_dev)) {
> > -			dev_err(dev, "vpu pdev failed\n");
> > -			of_node_put(vpu_node);
> > -		}
> > -
> >  		ret = v4l2_device_register(dev, &mdp->v4l2_dev);
> >  		if (ret) {
> >  			dev_err(dev, "Failed to register v4l2
> > device\n");
> > @@ -187,9 +208,8 @@ static int mtk_mdp_comp_bind(struct device
> > *dev,
> > struct device *master, void *da
> >  		}
> >  
> >  		/*
> > -		 * presence of the "mediatek,vpu" property in a device
> > node
> > -		 * indicates that it is the primary MDP rdma device and
> > MDP DMA
> > -		 * ops should be handled by its DMA callbacks.
> > +		 * MDP DMA ops will be handled by the DMA callbacks
> > associated with this
> > +		 * device;
> >  		 */
> >  		mdp->rdma_dev = dev;
> >  	}
> > diff --git a/drivers/media/platform/mtk-mdp/mtk_mdp_core.c
> > b/drivers/media/platform/mtk-mdp/mtk_mdp_core.c
> > index 50eafcc9993d..6a775463399c 100644
> > --- a/drivers/media/platform/mtk-mdp/mtk_mdp_core.c
> > +++ b/drivers/media/platform/mtk-mdp/mtk_mdp_core.c
> > @@ -150,8 +150,9 @@ static void release_of(struct device *dev, void
> > *data)
> >  
> >  static int mtk_mdp_master_bind(struct device *dev)
> >  {
> > -	int status;
> >  	struct mtk_mdp_dev *mdp = dev_get_drvdata(dev);
> > +	struct device_node *vpu_node;
> > +	int status;
> >  
> >  	status = component_bind_all(dev, mdp);
> >  	if (status) {
> > @@ -159,15 +160,30 @@ static int mtk_mdp_master_bind(struct device
> > *dev)
> >  		goto err_component_bind_all;
> >  	}
> >  
> > -	if (mdp->vpu_dev) {
> > -		int ret = vpu_wdt_reg_handler(mdp->vpu_dev,
> > mtk_mdp_reset_handler, mdp,
> > -					  VPU_RST_MDP);
> > -		if (ret) {
> > -			dev_err(dev, "Failed to register reset
> > handler\n");
> > -			goto err_wdt_reg;
> > -		}
> > -	} else {
> > -		dev_err(dev, "no vpu_dev found\n");
> > +	if (mdp->rdma_dev == NULL) {
> > +		dev_err(dev, "Primary MDP device not found");
> > +		status = -ENODEV;
> > +		goto err_component_bind_all;
> > +	}
> > +
> > +	vpu_node = of_find_node_by_name(NULL, "vpu");
> > +	if (!vpu_node) {
> > +		dev_err(dev, "unable to find vpu node");
> > +		status = -ENODEV;
> > +		goto err_wdt_reg;
> > +	}

Hi Eizan,

Is your removing "mediatek,vpu" necessary for this series "Refactor MTK
MDP driver into core/components" ?

In some MediaTek projects (not upstream yet), the device-tree node name
"vpu" may be changed to something like "vpu0", "vpu1" or other name,
which depends on the implementation of "mtk-vpu" driver. We can specify
the different phandle to "mediatek,vpu" in .dtsi file. If we use
of_find_node_by_name() to get the vpu_node, we have to modify the name
string in different project.
If the answer of my previous questions is "No", I prefer to slow down
the modification of removing "mediatek,vpu".

Sorry for late reply.

Regards,
Houlong

> > +
> > +	mdp->vpu_dev = of_find_device_by_node(vpu_node);
> > +	if (!mdp->vpu_dev) {
> > +		dev_err(dev, "unable to find vpu device");
> > +		status = -ENODEV;
> > +		goto err_wdt_reg;
> > +	}
> > +
> > +	status = vpu_wdt_reg_handler(mdp->vpu_dev,
> > mtk_mdp_reset_handler, mdp, VPU_RST_MDP);
> > +	if (status) {
> > +		dev_err(dev, "Failed to register reset handler\n");
> > +		goto err_wdt_reg;
> >  	}
> >  
> >  	status = mtk_mdp_register_m2m_device(mdp);
> > -- 
> > 2.32.0.554.ge1b32706d8-goog
> > 
> 
>