diff mbox series

[v9,07/18] drm: bridge: samsung-dsim: Lookup OF-graph or Child node devices

Message ID 20221209152343.180139-8-jagan@amarulasolutions.com
State New
Headers
Series drm: bridge: Add Samsung MIPI DSIM bridge |

Commit Message

Jagan Teki Dec. 9, 2022, 3:23 p.m. UTC 
The child devices in MIPI DSI can be binding with OF-graph
and also via child nodes.

The OF-graph interface represents the child devices via
remote and associated endpoint numbers like

dsi {
   compatible = "fsl,imx8mm-mipi-dsim";

   ports {
	port@0 {
	     reg = <0>;

	     dsi_in_lcdif: endpoint@0 {
		  reg = <0>;
		  remote-endpoint = <&lcdif_out_dsi>;
	     };
	};

	port@1 {
	     reg = <1>;

	     dsi_out_bridge: endpoint {
		  remote-endpoint = <&bridge_in_dsi>;
	     };
	};
};

The child node interface represents the child devices via
conventional child nodes on given DSI parent like

dsi {
   compatible = "samsung,exynos5433-mipi-dsi";

   ports {
        port@0 {
             reg = <0>;

             dsi_to_mic: endpoint {
                  remote-endpoint = <&mic_to_dsi>;
             };
        };
   };

   panel@0 {
        reg = <0>;
   };
};

As Samsung DSIM bridge is common DSI IP across all Exynos DSI
and NXP i.MX8M host controllers, this patch adds support to
lookup the child devices whether its bindings on the associated
host represent OF-graph or child node interfaces.

v9, v8, v7, v6, v5, v4, v3:
* none

v2:
* new patch

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
---
 drivers/gpu/drm/bridge/samsung-dsim.c | 38 +++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

Comments

Marek Vasut Dec. 11, 2022, 2:24 a.m. UTC | #1 
On 12/9/22 16:23, Jagan Teki wrote:
> The child devices in MIPI DSI can be binding with OF-graph
> and also via child nodes.
> 
> The OF-graph interface represents the child devices via
> remote and associated endpoint numbers like
> 
> dsi {
>     compatible = "fsl,imx8mm-mipi-dsim";
> 
>     ports {
> 	port@0 {
> 	     reg = <0>;
> 
> 	     dsi_in_lcdif: endpoint@0 {
> 		  reg = <0>;
> 		  remote-endpoint = <&lcdif_out_dsi>;
> 	     };
> 	};
> 
> 	port@1 {
> 	     reg = <1>;
> 
> 	     dsi_out_bridge: endpoint {
> 		  remote-endpoint = <&bridge_in_dsi>;
> 	     };
> 	};
> };
> 
> The child node interface represents the child devices via
> conventional child nodes on given DSI parent like
> 
> dsi {
>     compatible = "samsung,exynos5433-mipi-dsi";
> 
>     ports {
>          port@0 {
>               reg = <0>;
> 
>               dsi_to_mic: endpoint {
>                    remote-endpoint = <&mic_to_dsi>;
>               };
>          };
>     };
> 
>     panel@0 {
>          reg = <0>;
>     };
> };
> 
> As Samsung DSIM bridge is common DSI IP across all Exynos DSI
> and NXP i.MX8M host controllers, this patch adds support to
> lookup the child devices whether its bindings on the associated
> host represent OF-graph or child node interfaces.
> 
> v9, v8, v7, v6, v5, v4, v3:
> * none
> 
> v2:
> * new patch

This looks like a good candidate for common/helper code which can be 
reused by other similar drivers.
Jagan Teki Dec. 11, 2022, 5:42 a.m. UTC | #2 
On Sun, Dec 11, 2022 at 7:58 AM Marek Vasut <marex@denx.de> wrote:
>
> On 12/9/22 16:23, Jagan Teki wrote:
> > The child devices in MIPI DSI can be binding with OF-graph
> > and also via child nodes.
> >
> > The OF-graph interface represents the child devices via
> > remote and associated endpoint numbers like
> >
> > dsi {
> >     compatible = "fsl,imx8mm-mipi-dsim";
> >
> >     ports {
> >       port@0 {
> >            reg = <0>;
> >
> >            dsi_in_lcdif: endpoint@0 {
> >                 reg = <0>;
> >                 remote-endpoint = <&lcdif_out_dsi>;
> >            };
> >       };
> >
> >       port@1 {
> >            reg = <1>;
> >
> >            dsi_out_bridge: endpoint {
> >                 remote-endpoint = <&bridge_in_dsi>;
> >            };
> >       };
> > };
> >
> > The child node interface represents the child devices via
> > conventional child nodes on given DSI parent like
> >
> > dsi {
> >     compatible = "samsung,exynos5433-mipi-dsi";
> >
> >     ports {
> >          port@0 {
> >               reg = <0>;
> >
> >               dsi_to_mic: endpoint {
> >                    remote-endpoint = <&mic_to_dsi>;
> >               };
> >          };
> >     };
> >
> >     panel@0 {
> >          reg = <0>;
> >     };
> > };
> >
> > As Samsung DSIM bridge is common DSI IP across all Exynos DSI
> > and NXP i.MX8M host controllers, this patch adds support to
> > lookup the child devices whether its bindings on the associated
> > host represent OF-graph or child node interfaces.
> >
> > v9, v8, v7, v6, v5, v4, v3:
> > * none
> >
> > v2:
> > * new patch
>
> This looks like a good candidate for common/helper code which can be
> reused by other similar drivers.

Yes, I have responded to the same comment of yours in v7 [1]. It is
hard to make this code work in a generic way.

[1] https://lore.kernel.org/all/CAMty3ZBtRZ-vDPQYX+m8uWmsD+vmbFOnCGVba8swQ8GWtWaKJQ@mail.gmail.com/
Marek Vasut Dec. 11, 2022, 6:06 p.m. UTC | #3 
On 12/11/22 06:42, Jagan Teki wrote:
> On Sun, Dec 11, 2022 at 7:58 AM Marek Vasut <marex@denx.de> wrote:
>>
>> On 12/9/22 16:23, Jagan Teki wrote:
>>> The child devices in MIPI DSI can be binding with OF-graph
>>> and also via child nodes.
>>>
>>> The OF-graph interface represents the child devices via
>>> remote and associated endpoint numbers like
>>>
>>> dsi {
>>>      compatible = "fsl,imx8mm-mipi-dsim";
>>>
>>>      ports {
>>>        port@0 {
>>>             reg = <0>;
>>>
>>>             dsi_in_lcdif: endpoint@0 {
>>>                  reg = <0>;
>>>                  remote-endpoint = <&lcdif_out_dsi>;
>>>             };
>>>        };
>>>
>>>        port@1 {
>>>             reg = <1>;
>>>
>>>             dsi_out_bridge: endpoint {
>>>                  remote-endpoint = <&bridge_in_dsi>;
>>>             };
>>>        };
>>> };
>>>
>>> The child node interface represents the child devices via
>>> conventional child nodes on given DSI parent like
>>>
>>> dsi {
>>>      compatible = "samsung,exynos5433-mipi-dsi";
>>>
>>>      ports {
>>>           port@0 {
>>>                reg = <0>;
>>>
>>>                dsi_to_mic: endpoint {
>>>                     remote-endpoint = <&mic_to_dsi>;
>>>                };
>>>           };
>>>      };
>>>
>>>      panel@0 {
>>>           reg = <0>;
>>>      };
>>> };
>>>
>>> As Samsung DSIM bridge is common DSI IP across all Exynos DSI
>>> and NXP i.MX8M host controllers, this patch adds support to
>>> lookup the child devices whether its bindings on the associated
>>> host represent OF-graph or child node interfaces.
>>>
>>> v9, v8, v7, v6, v5, v4, v3:
>>> * none
>>>
>>> v2:
>>> * new patch
>>
>> This looks like a good candidate for common/helper code which can be
>> reused by other similar drivers.
> 
> Yes, I have responded to the same comment of yours in v7 [1]. It is
> hard to make this code work in a generic way.

It seems the patch adds a for_each...() loop and a function call. Should 
be easy enough to turn that into a helper. What am I missing ?
Jagan Teki Dec. 12, 2022, 9:34 a.m. UTC | #4 
On Sun, Dec 11, 2022 at 11:36 PM Marek Vasut <marex@denx.de> wrote:
>
> On 12/11/22 06:42, Jagan Teki wrote:
> > On Sun, Dec 11, 2022 at 7:58 AM Marek Vasut <marex@denx.de> wrote:
> >>
> >> On 12/9/22 16:23, Jagan Teki wrote:
> >>> The child devices in MIPI DSI can be binding with OF-graph
> >>> and also via child nodes.
> >>>
> >>> The OF-graph interface represents the child devices via
> >>> remote and associated endpoint numbers like
> >>>
> >>> dsi {
> >>>      compatible = "fsl,imx8mm-mipi-dsim";
> >>>
> >>>      ports {
> >>>        port@0 {
> >>>             reg = <0>;
> >>>
> >>>             dsi_in_lcdif: endpoint@0 {
> >>>                  reg = <0>;
> >>>                  remote-endpoint = <&lcdif_out_dsi>;
> >>>             };
> >>>        };
> >>>
> >>>        port@1 {
> >>>             reg = <1>;
> >>>
> >>>             dsi_out_bridge: endpoint {
> >>>                  remote-endpoint = <&bridge_in_dsi>;
> >>>             };
> >>>        };
> >>> };
> >>>
> >>> The child node interface represents the child devices via
> >>> conventional child nodes on given DSI parent like
> >>>
> >>> dsi {
> >>>      compatible = "samsung,exynos5433-mipi-dsi";
> >>>
> >>>      ports {
> >>>           port@0 {
> >>>                reg = <0>;
> >>>
> >>>                dsi_to_mic: endpoint {
> >>>                     remote-endpoint = <&mic_to_dsi>;
> >>>                };
> >>>           };
> >>>      };
> >>>
> >>>      panel@0 {
> >>>           reg = <0>;
> >>>      };
> >>> };
> >>>
> >>> As Samsung DSIM bridge is common DSI IP across all Exynos DSI
> >>> and NXP i.MX8M host controllers, this patch adds support to
> >>> lookup the child devices whether its bindings on the associated
> >>> host represent OF-graph or child node interfaces.
> >>>
> >>> v9, v8, v7, v6, v5, v4, v3:
> >>> * none
> >>>
> >>> v2:
> >>> * new patch
> >>
> >> This looks like a good candidate for common/helper code which can be
> >> reused by other similar drivers.
> >
> > Yes, I have responded to the same comment of yours in v7 [1]. It is
> > hard to make this code work in a generic way.
>
> It seems the patch adds a for_each...() loop and a function call. Should
> be easy enough to turn that into a helper. What am I missing ?

What I'm saying here is, initially, I added for_each in the existing
drm_of_find_panel_or_bridge helper but it fails to handle all drm_of
use cases generically. You can find more information on this commit
80253168dbfd. I keep this in mind and will see whether it can support
the new dsi helper once this supported is merged. Hope I'm clear on
it.

Jagan.
diff mbox series

Patch

diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
index baad09b2daeb..a4379c2ccb77 100644
--- a/drivers/gpu/drm/bridge/samsung-dsim.c
+++ b/drivers/gpu/drm/bridge/samsung-dsim.c
@@ -1356,18 +1356,52 @@  static int samsung_dsim_host_attach(struct mipi_dsi_host *host,
 	struct samsung_dsim *dsi = host_to_dsi(host);
 	const struct samsung_dsim_plat_data *pdata = dsi->plat_data;
 	struct device *dev = dsi->dev;
+	struct device_node *np = dev->of_node;
+	struct device_node *remote;
 	struct drm_panel *panel;
 	int ret;
 
-	panel = of_drm_find_panel(device->dev.of_node);
+	/**
+	 * Devices can also be child nodes when we also control that device
+	 * through the upstream device (ie, MIPI-DCS for a MIPI-DSI device).
+	 *
+	 * Lookup for a child node of the given parent that isn't either port
+	 * or ports.
+	 */
+	for_each_available_child_of_node(np, remote) {
+		if (of_node_name_eq(remote, "port") ||
+		    of_node_name_eq(remote, "ports"))
+			continue;
+
+		goto of_find_panel_or_bridge;
+	}
+
+	/*
+	 * of_graph_get_remote_node() produces a noisy error message if port
+	 * node isn't found and the absence of the port is a legit case here,
+	 * so at first we silently check whether graph presents in the
+	 * device-tree node.
+	 */
+	if (!of_graph_is_present(np))
+		return -ENODEV;
+
+	remote = of_graph_get_remote_node(np, 1, 0);
+
+of_find_panel_or_bridge:
+	if (!remote)
+		return -ENODEV;
+
+	panel = of_drm_find_panel(remote);
 	if (!IS_ERR(panel)) {
 		dsi->out_bridge = devm_drm_panel_bridge_add(dev, panel);
 	} else {
-		dsi->out_bridge = of_drm_find_bridge(device->dev.of_node);
+		dsi->out_bridge = of_drm_find_bridge(remote);
 		if (!dsi->out_bridge)
 			dsi->out_bridge = ERR_PTR(-EINVAL);
 	}
 
+	of_node_put(remote);
+
 	if (IS_ERR(dsi->out_bridge)) {
 		ret = PTR_ERR(dsi->out_bridge);
 		DRM_DEV_ERROR(dev, "failed to find the bridge: %d\n", ret);