diff mbox series

[v13,03/10] drm/display: Add Type-C switch helpers

Message ID 20230303143350.815623-4-treapking@chromium.org (mailing list archive)
State New, archived
Headers show
Series Register Type-C mode-switch in DP bridge endpoints | expand

Commit Message

Pin-yen Lin March 3, 2023, 2:33 p.m. UTC 
Add helpers to register and unregister Type-C "switches" for bridges
capable of switching their output between two downstream devices.

The helper registers USB Type-C mode switches when the "mode-switch"
and the "reg" properties are available in Device Tree.

Signed-off-by: Pin-yen Lin <treapking@chromium.org>

---

Changes in v13:
- Add typec_mode_switch_node_count helper
- Fix style issues

Changes in v12:
- Add fwnode_for_each_typec_mode_switch macro
- Remove a duplicated dmesg in the helper
- Used IS_REACHABLE instead to guard the function signatures

Changes in v11:
- Use fwnode helpers instead of DT
- Moved the helpers to a new file
- Use "reg" instead of "data-lanes" to determine the port number
- Dropped collected tags due to new changes

Changes in v10:
- Collected Reviewed-by and Tested-by tags
- Replaced "void *" with "typec_mux_set_fn_t" for mux_set callbacks
- Print out the node name when errors on parsing DT
- Use dev_dbg instead of dev_warn when no Type-C switch nodes available
- Made the return path of drm_dp_register_mode_switch clearer

Changes in v8:
- Fixed the build issue when CONFIG_TYPEC=m
- Fixed some style issues

Changes in v7:
- Extracted the common codes to a helper function
- New in v7

 drivers/gpu/drm/display/Makefile              |   1 +
 drivers/gpu/drm/display/drm_dp_typec_helper.c | 105 ++++++++++++++++++
 include/drm/display/drm_dp_helper.h           |  46 ++++++++
 3 files changed, 152 insertions(+)
 create mode 100644 drivers/gpu/drm/display/drm_dp_typec_helper.c

Comments

Andy Shevchenko March 6, 2023, 11:49 a.m. UTC | #1 
On Fri, Mar 03, 2023 at 10:33:43PM +0800, Pin-yen Lin wrote:
> Add helpers to register and unregister Type-C "switches" for bridges
> capable of switching their output between two downstream devices.
> 
> The helper registers USB Type-C mode switches when the "mode-switch"
> and the "reg" properties are available in Device Tree.

...

> +	port_data->typec_mux = typec_mux_register(dev, &mux_desc);
> +	if (IS_ERR(port_data->typec_mux)) {
> +		ret = PTR_ERR(port_data->typec_mux);
> +		dev_err(dev, "Mode switch register for port %d failed: %d\n",
> +			port_num, ret);

> +		return ret;
> +	}
> +
> +	return 0;

Can be simply

	port_data->typec_mux = typec_mux_register(dev, &mux_desc);
	ret = PTR_ERR_OR_ZERO(port_data->typec_mux);
	if (ret)
		dev_err(dev, "Mode switch register for port %d failed: %d\n",
			port_num, ret);

	return ret;

...

> +	switch_desc->typec_ports = devm_kcalloc(dev, switch_desc->num_typec_switches,
> +						sizeof(struct drm_dp_typec_port_data),
> +						GFP_KERNEL);
> +	if (!switch_desc->typec_ports)
> +		return -ENOMEM;

How often this function _can_ be called during the runtime?
If it's _possible_ to call it infinite times, consider *not* using devm.
Pin-yen Lin March 8, 2023, 10:20 a.m. UTC | #2 
Hi Andy,

Thanks for the review.

On Mon, Mar 6, 2023 at 7:49 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Fri, Mar 03, 2023 at 10:33:43PM +0800, Pin-yen Lin wrote:
> > Add helpers to register and unregister Type-C "switches" for bridges
> > capable of switching their output between two downstream devices.
> >
> > The helper registers USB Type-C mode switches when the "mode-switch"
> > and the "reg" properties are available in Device Tree.
>
> ...
>
> > +     port_data->typec_mux = typec_mux_register(dev, &mux_desc);
> > +     if (IS_ERR(port_data->typec_mux)) {
> > +             ret = PTR_ERR(port_data->typec_mux);
> > +             dev_err(dev, "Mode switch register for port %d failed: %d\n",
> > +                     port_num, ret);
>
> > +             return ret;
> > +     }
> > +
> > +     return 0;
>
> Can be simply
>
>         port_data->typec_mux = typec_mux_register(dev, &mux_desc);
>         ret = PTR_ERR_OR_ZERO(port_data->typec_mux);
>         if (ret)
>                 dev_err(dev, "Mode switch register for port %d failed: %d\n",
>                         port_num, ret);
>
>         return ret;
>
This was suggested by Angelo in [1], but you are not the first
reviewer that finds this weird... I'll update this in the next
version.

[1]: https://lore.kernel.org/all/023519eb-0adb-3b08-71b9-afb92a6cceaf@collabora.com/

> ...
>
> > +     switch_desc->typec_ports = devm_kcalloc(dev, switch_desc->num_typec_switches,
> > +                                             sizeof(struct drm_dp_typec_port_data),
> > +                                             GFP_KERNEL);
> > +     if (!switch_desc->typec_ports)
> > +             return -ENOMEM;
>
> How often this function _can_ be called during the runtime?
> If it's _possible_ to call it infinite times, consider *not* using devm.

I would expect this function to be only called during driver probing,
and this is the case for the current users in this series. So I think
this is only called once if EPROBDE_DEFER doesn't count.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
Best regards,
Pin-yen
Andy Shevchenko March 8, 2023, 3:28 p.m. UTC | #3 
On Wed, Mar 08, 2023 at 06:20:14PM +0800, Pin-yen Lin wrote:
> On Mon, Mar 6, 2023 at 7:49 PM Andy Shevchenko
> > On Fri, Mar 03, 2023 at 10:33:43PM +0800, Pin-yen Lin wrote:

...

> > > +     switch_desc->typec_ports = devm_kcalloc(dev, switch_desc->num_typec_switches,
> > > +                                             sizeof(struct drm_dp_typec_port_data),
> > > +                                             GFP_KERNEL);
> > > +     if (!switch_desc->typec_ports)
> > > +             return -ENOMEM;
> >
> > How often this function _can_ be called during the runtime?
> > If it's _possible_ to call it infinite times, consider *not* using devm.
> 
> I would expect this function to be only called during driver probing,
> and this is the case for the current users in this series. So I think
> this is only called once if EPROBDE_DEFER doesn't count.

No, deferred probe is not counted.

Can you add a word somewhere in the comment(?) to make this clear?
Pin-yen Lin March 9, 2023, 10:20 a.m. UTC | #4 
Hi Andy,

On Wed, Mar 8, 2023 at 11:29 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Wed, Mar 08, 2023 at 06:20:14PM +0800, Pin-yen Lin wrote:
> > On Mon, Mar 6, 2023 at 7:49 PM Andy Shevchenko
> > > On Fri, Mar 03, 2023 at 10:33:43PM +0800, Pin-yen Lin wrote:
>
> ...
>
> > > > +     switch_desc->typec_ports = devm_kcalloc(dev, switch_desc->num_typec_switches,
> > > > +                                             sizeof(struct drm_dp_typec_port_data),
> > > > +                                             GFP_KERNEL);
> > > > +     if (!switch_desc->typec_ports)
> > > > +             return -ENOMEM;
> > >
> > > How often this function _can_ be called during the runtime?
> > > If it's _possible_ to call it infinite times, consider *not* using devm.
> >
> > I would expect this function to be only called during driver probing,
> > and this is the case for the current users in this series. So I think
> > this is only called once if EPROBDE_DEFER doesn't count.
>
> No, deferred probe is not counted.
>
> Can you add a word somewhere in the comment(?) to make this clear?

Sure. I'll add some note in the comments about this.
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
Thanks and regards,
Pin-yen
diff mbox series

Patch

diff --git a/drivers/gpu/drm/display/Makefile b/drivers/gpu/drm/display/Makefile
index 17ac4a1006a8..ef80b9fde615 100644
--- a/drivers/gpu/drm/display/Makefile
+++ b/drivers/gpu/drm/display/Makefile
@@ -14,5 +14,6 @@  drm_display_helper-$(CONFIG_DRM_DISPLAY_HDMI_HELPER) += \
 	drm_scdc_helper.o
 drm_display_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o
 drm_display_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o
+drm_display_helper-$(CONFIG_TYPEC) += drm_dp_typec_helper.o
 
 obj-$(CONFIG_DRM_DISPLAY_HELPER) += drm_display_helper.o
diff --git a/drivers/gpu/drm/display/drm_dp_typec_helper.c b/drivers/gpu/drm/display/drm_dp_typec_helper.c
new file mode 100644
index 000000000000..0c705a4bca24
--- /dev/null
+++ b/drivers/gpu/drm/display/drm_dp_typec_helper.c
@@ -0,0 +1,105 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/usb/typec_mux.h>
+#include <drm/display/drm_dp_helper.h>
+
+static int drm_dp_register_mode_switch(struct device *dev,
+				       struct fwnode_handle *fwnode,
+				       struct drm_dp_typec_switch_desc *switch_desc,
+				       void *data, typec_mux_set_fn_t mux_set)
+{
+	struct drm_dp_typec_port_data *port_data;
+	struct typec_mux_desc mux_desc = {};
+	char name[32];
+	u32 port_num;
+	int ret;
+
+	ret = fwnode_property_read_u32(fwnode, "reg", &port_num);
+	if (ret) {
+		dev_err(dev, "Failed to read reg property: %d\n", ret);
+		return ret;
+	}
+
+	port_data = &switch_desc->typec_ports[port_num];
+	port_data->data = data;
+	port_data->port_num = port_num;
+	port_data->fwnode = fwnode;
+	mux_desc.fwnode = fwnode;
+	mux_desc.drvdata = port_data;
+	snprintf(name, sizeof(name), "%pfwP-%u", fwnode, port_num);
+	mux_desc.name = name;
+	mux_desc.set = mux_set;
+
+	port_data->typec_mux = typec_mux_register(dev, &mux_desc);
+	if (IS_ERR(port_data->typec_mux)) {
+		ret = PTR_ERR(port_data->typec_mux);
+		dev_err(dev, "Mode switch register for port %d failed: %d\n",
+			port_num, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * drm_dp_register_typec_switches() - register Type-C switches
+ * @dev: Device that registers Type-C switches
+ * @port: Device node for the switch
+ * @switch_desc: A Type-C switch descriptor
+ * @data: Private data for the switches
+ * @mux_set: Callback function for typec_mux_set
+ *
+ * This function registers USB Type-C switches for DP bridges that can switch
+ * the output signal between their output pins.
+ *
+ * Currently only mode switches are implemented, and the function assumes the
+ * given @port device node has endpoints with "mode-switch" property.
+ * The port number is determined by the "reg" property of the endpoint.
+ */
+int drm_dp_register_typec_switches(struct device *dev, struct fwnode_handle *port,
+				   struct drm_dp_typec_switch_desc *switch_desc,
+				   void *data, typec_mux_set_fn_t mux_set)
+{
+	struct fwnode_handle *sw;
+	int ret;
+
+	switch_desc->num_typec_switches = typec_mode_switch_node_count(port);
+	if (!switch_desc->num_typec_switches) {
+		dev_dbg(dev, "No Type-C switches node found\n");
+		return 0;
+	}
+
+	switch_desc->typec_ports = devm_kcalloc(dev, switch_desc->num_typec_switches,
+						sizeof(struct drm_dp_typec_port_data),
+						GFP_KERNEL);
+	if (!switch_desc->typec_ports)
+		return -ENOMEM;
+
+	/* Register switches for each connector. */
+	for_each_typec_mode_switch_node(port, sw) {
+		ret = drm_dp_register_mode_switch(dev, sw, switch_desc, data, mux_set);
+		if (ret)
+			goto err_unregister_typec_switches;
+	}
+
+	return 0;
+
+err_unregister_typec_switches:
+	fwnode_handle_put(sw);
+	drm_dp_unregister_typec_switches(switch_desc);
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_register_typec_switches);
+
+/**
+ * drm_dp_unregister_typec_switches() - unregister Type-C switches
+ * @switch_desc: A Type-C switch descriptor
+ */
+void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc)
+{
+	unsigned int i;
+
+	for (i = 0; i < switch_desc->num_typec_switches; i++)
+		typec_mux_unregister(switch_desc->typec_ports[i].typec_mux);
+}
+EXPORT_SYMBOL(drm_dp_unregister_typec_switches);
diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index ab55453f2d2c..fb359b0cc8e8 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -25,6 +25,7 @@ 
 
 #include <linux/delay.h>
 #include <linux/i2c.h>
+#include <linux/usb/typec_mux.h>
 
 #include <drm/display/drm_dp.h>
 #include <drm/drm_connector.h>
@@ -763,4 +764,49 @@  bool drm_dp_downstream_rgb_to_ycbcr_conversion(const u8 dpcd[DP_RECEIVER_CAP_SIZ
 					       const u8 port_cap[4], u8 color_spc);
 int drm_dp_pcon_convert_rgb_to_ycbcr(struct drm_dp_aux *aux, u8 color_spc);
 
+struct drm_dp_typec_port_data {
+	struct typec_mux_dev *typec_mux;
+	int port_num;
+	struct fwnode_handle *fwnode;
+	void *data;
+};
+
+struct drm_dp_typec_switch_desc {
+	int num_typec_switches;
+	struct drm_dp_typec_port_data *typec_ports;
+};
+
+#define for_each_typec_mode_switch_node(port, sw)	\
+	fwnode_for_each_child_node((port), (sw))	\
+		for_each_if(fwnode_property_present((sw), "mode-switch"))
+
+static inline unsigned int typec_mode_switch_node_count(struct fwnode_handle *port)
+{
+	struct fwnode_handle *sw;
+	unsigned int count = 0;
+
+	for_each_typec_mode_switch_node(port, sw)
+		count++;
+
+	return count;
+}
+
+#if IS_REACHABLE(CONFIG_TYPEC)
+void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc);
+int drm_dp_register_typec_switches(struct device *dev, struct fwnode_handle *port,
+				   struct drm_dp_typec_switch_desc *switch_desc,
+				   void *data, typec_mux_set_fn_t mux_set);
+#else
+static inline void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc)
+{
+}
+static inline int drm_dp_register_typec_switches(
+		struct device *dev, struct fwnode_handle *port,
+		struct drm_dp_typec_switch_desc *switch_desc, void *data,
+		typec_mux_set_fn_t mux_set)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
 #endif /* _DRM_DP_HELPER_H_ */