[v13,03/10] drm/display: Add Type-C switch helpers
Commit Message
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
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.
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
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?
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
@@ -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
new file mode 100644
@@ -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);
@@ -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_ */