Re: [PATCH 3/5] drm: convert drivers to use of_graph_get_remote_node

[Rob Herring]

On Mon, Feb 06, 2017 at 10:29:33AM +0000, Liviu Dudau wrote:
> On Fri, Feb 03, 2017 at 09:36:33PM -0600, Rob Herring wrote:
> > Convert drivers to use the new of_graph_get_remote_node() helper
> > instead of parsing the endpoint node and then getting the remote device
> > node. Now drivers can just specify the device node and which
> > port/endpoint and get back the connected remote device node. The details
> > of the graph binding are nicely abstracted into the core OF graph code.
> > 
> > This changes some error messages to debug messages (in the graph core).
> > Graph connections are often "no connects" depending on the particular
> > board, so we want to avoid spurious messages. Plus the kernel is not a
> > DT validator.
> > 
> > Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
> > ---
> >  drivers/gpu/drm/arm/hdlcd_drv.c                 | 22 ++-------
> >  drivers/gpu/drm/arm/malidp_drv.c                | 29 ++---------
> >  drivers/gpu/drm/bridge/adv7511/adv7533.c        | 12 +----
> >  drivers/gpu/drm/bridge/dumb-vga-dac.c           | 15 ++----
> >  drivers/gpu/drm/bridge/ti-tfp410.c              | 15 ++----
> >  drivers/gpu/drm/exynos/exynos_drm_dpi.c         | 16 +-----
> >  drivers/gpu/drm/exynos/exynos_drm_dsi.c         | 13 ++---
> >  drivers/gpu/drm/exynos/exynos_drm_mic.c         | 27 +---------
> >  drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c    | 26 ++--------
> >  drivers/gpu/drm/hisilicon/kirin/kirin_drm_drv.c | 30 +----------
> >  drivers/gpu/drm/mediatek/mtk_dpi.c              | 12 ++---
> >  drivers/gpu/drm/mediatek/mtk_hdmi.c             | 26 ++--------
> >  drivers/gpu/drm/meson/meson_drv.c               | 12 ++---
> >  drivers/gpu/drm/meson/meson_venc_cvbs.c         | 19 ++-----
> >  drivers/gpu/drm/msm/dsi/dsi_host.c              |  3 +-
> >  drivers/gpu/drm/msm/mdp/mdp4/mdp4_kms.c         | 28 +----------
> >  drivers/gpu/drm/rockchip/rockchip_drm_drv.c     | 18 +++----
> >  drivers/gpu/drm/tilcdc/tilcdc_crtc.c            | 11 +----
> >  drivers/gpu/drm/tilcdc/tilcdc_external.c        | 66 +++----------------------
> >  drivers/gpu/drm/vc4/vc4_dpi.c                   | 15 ++----
> >  20 files changed, 64 insertions(+), 351 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/arm/hdlcd_drv.c b/drivers/gpu/drm/arm/hdlcd_drv.c
> > index e5f4f4a6546d..0f70f5fe9970 100644
> > --- a/drivers/gpu/drm/arm/hdlcd_drv.c
> > +++ b/drivers/gpu/drm/arm/hdlcd_drv.c
> > @@ -430,29 +430,13 @@ static int compare_dev(struct device *dev, void *data)
> >  
> >  static int hdlcd_probe(struct platform_device *pdev)
> >  {
> > -	struct device_node *port, *ep;
> > +	struct device_node *port;
> >  	struct component_match *match = NULL;
> >  
> > -	if (!pdev->dev.of_node)
> > -		return -ENODEV;
> > -
> >  	/* there is only one output port inside each device, find it */
> > -	ep = of_graph_get_next_endpoint(pdev->dev.of_node, NULL);
> > -	if (!ep)
> > -		return -ENODEV;
> > -
> > -	if (!of_device_is_available(ep)) {
> > -		of_node_put(ep);
> > +	port = of_graph_get_remote_node(pdev->dev.of_node, 0, 0);
> > +	if (!port)
> >  		return -ENODEV;
> > -	}
> > -
> > -	/* add the remote encoder port as component */
> > -	port = of_graph_get_remote_port_parent(ep);
> > -	of_node_put(ep);
> > -	if (!port || !of_device_is_available(port)) {
> > -		of_node_put(port);
> > -		return -EAGAIN;
> 
> The HDLCD change looks reasonable except for this -EAGAIN business. I'll have to
> test your changes on my setup to see how this affects having the encoder as a module.

What are you expecting to happen with -EAGAIN? This one was a bit of an 
oddball. 

This condition would only change if you had an overlay. That's a use 
case that needs to be handled in a common way ('cause I don't want to 
clean-up every driver doing overlays in their own way latter). Just 
having "status" changing at runtime would have all sorts of implications 
in the kernel.

> 
> > -	}
> >  
> >  	drm_of_component_match_add(&pdev->dev, &match, compare_dev, port);
> >  	of_node_put(port);
> > diff --git a/drivers/gpu/drm/arm/malidp_drv.c b/drivers/gpu/drm/arm/malidp_drv.c
> > index 32f746e31379..bfa04be7f5de 100644
> > --- a/drivers/gpu/drm/arm/malidp_drv.c
> > +++ b/drivers/gpu/drm/arm/malidp_drv.c
> > @@ -262,7 +262,6 @@ static int malidp_bind(struct device *dev)
> >  {
> >  	struct resource *res;
> >  	struct drm_device *drm;
> > -	struct device_node *ep;
> >  	struct malidp_drm *malidp;
> >  	struct malidp_hw_device *hwdev;
> >  	struct platform_device *pdev = to_platform_device(dev);
> > @@ -360,12 +359,7 @@ static int malidp_bind(struct device *dev)
> >  		goto init_fail;
> >  
> >  	/* Set the CRTC's port so that the encoder component can find it */
> > -	ep = of_graph_get_next_endpoint(dev->of_node, NULL);
> > -	if (!ep) {
> > -		ret = -EINVAL;
> > -		goto port_fail;
> > -	}
> > -	malidp->crtc.port = of_get_next_parent(ep);
> > +	malidp->crtc.port = of_graph_get_port_by_id(dev->of_node, 0);
> >  
> >  	ret = component_bind_all(dev, drm);
> >  	if (ret) {
> > @@ -418,9 +412,7 @@ static int malidp_bind(struct device *dev)
> >  irq_init_fail:
> >  	component_unbind_all(dev, drm);
> >  bind_fail:
> > -	of_node_put(malidp->crtc.port);
> 
> Why removing this line? AFAICT this is still needed, according to of_graph_get_port_by_id()
> documentation.

Yes, you are right.

Rob