[v7,3/9] 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 "data-lanes" properties are available in Device Tree.
Signed-off-by: Pin-yen Lin <treapking@chromium.org>
---
Changes in v7:
- Extracted the common codes to a helper function
- New in v7
drivers/gpu/drm/display/drm_dp_helper.c | 132 ++++++++++++++++++++++++
include/drm/display/drm_dp_helper.h | 16 +++
2 files changed, 148 insertions(+)
Comments
On Thu, Jan 05, 2023 at 09:24:51PM +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 "data-lanes" 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;
...
> + struct device_node *sw;
> + int ret = 0;
It's easy to break things if you squeeze more code in the future in this
function, so I recommend to split assignment to be closer to its first user
(see below).
> + for_each_child_of_node(port, sw) {
> + if (of_property_read_bool(sw, "mode-switch"))
> + switch_desc->num_typec_switches++;
> + }
> +
> + if (!switch_desc->num_typec_switches) {
> + dev_warn(dev, "No Type-C switches node found\n");
> + return ret;
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_child_of_node(port, sw) {
> + if (!of_property_read_bool(sw, "mode-switch"))
> + continue;
> + ret = drm_dp_register_mode_switch(dev, sw, switch_desc, data, mux_set);
> + if (ret) {
> + dev_err(dev, "Failed to register mode switch: %d\n", ret);
> + of_node_put(sw);
> + break;
> + }
> + }
> + if (ret)
> + drm_dp_unregister_typec_switches(switch_desc);
> +
> + return ret;
Why not adding a goto label?
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:
of_node_put(sw);
drm_dp_unregister_typec_switches(switch_desc);
dev_err(dev, "Failed to register mode switch: %d\n", ret);
return ret;
Hi Pin-yen,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on drm-misc/drm-misc-next]
[also build test ERROR on driver-core/driver-core-testing driver-core/driver-core-next driver-core/driver-core-linus chrome-platform/for-next drm/drm-next linus/master v6.2-rc2 next-20230105]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Pin-yen-Lin/device-property-Add-remote-endpoint-to-devcon-matcher/20230105-212902
base: git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link: https://lore.kernel.org/r/20230105132457.4125372-4-treapking%40chromium.org
patch subject: [PATCH v7 3/9] drm/display: Add Type-C switch helpers
config: arm-defconfig
compiler: arm-linux-gnueabi-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/c037bdca262df88564fff58cb5233d50180c7215
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Pin-yen-Lin/device-property-Add-remote-endpoint-to-devcon-matcher/20230105-212902
git checkout c037bdca262df88564fff58cb5233d50180c7215
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
All errors (new ones prefixed by >>):
arm-linux-gnueabi-ld: drivers/gpu/drm/display/drm_dp_helper.o: in function `drm_dp_unregister_typec_switches':
>> drm_dp_helper.c:(.text+0x1298): undefined reference to `typec_mux_unregister'
arm-linux-gnueabi-ld: drivers/gpu/drm/display/drm_dp_helper.o: in function `drm_dp_register_typec_switches':
>> drm_dp_helper.c:(.text+0x160c): undefined reference to `typec_mux_register'
>> arm-linux-gnueabi-ld: drm_dp_helper.c:(.text+0x16e8): undefined reference to `typec_mux_unregister'
Hi Andy,
Thanks for the review.
On Thu, Jan 5, 2023 at 11:41 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>
> On Thu, Jan 05, 2023 at 09:24:51PM +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 "data-lanes" 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;
>
> ...
>
> > + struct device_node *sw;
>
> > + int ret = 0;
>
> It's easy to break things if you squeeze more code in the future in this
> function, so I recommend to split assignment to be closer to its first user
> (see below).
>
> > + for_each_child_of_node(port, sw) {
> > + if (of_property_read_bool(sw, "mode-switch"))
> > + switch_desc->num_typec_switches++;
> > + }
> > +
> > + if (!switch_desc->num_typec_switches) {
> > + dev_warn(dev, "No Type-C switches node found\n");
>
> > + return ret;
>
> return 0;
Thanks for the suggestion. I'll update this in v8.
>
> > + }
> > +
> > + 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_child_of_node(port, sw) {
> > + if (!of_property_read_bool(sw, "mode-switch"))
> > + continue;
> > + ret = drm_dp_register_mode_switch(dev, sw, switch_desc, data, mux_set);
> > + if (ret) {
> > + dev_err(dev, "Failed to register mode switch: %d\n", ret);
> > + of_node_put(sw);
> > + break;
> > + }
> > + }
>
> > + if (ret)
> > + drm_dp_unregister_typec_switches(switch_desc);
> > +
> > + return ret;
>
> Why not adding a goto label?
I didn't know that goto label is preferred even when there are no
duplicated code blocks in the function.
I'll update this accordingly in v8.
>
> 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:
> of_node_put(sw);
> drm_dp_unregister_typec_switches(switch_desc);
> dev_err(dev, "Failed to register mode switch: %d\n", ret);
> return ret;
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
Best regards,
Pin-yen
@@ -30,11 +30,13 @@
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/string_helpers.h>
+#include <linux/usb/typec_mux.h>
#include <linux/dynamic_debug.h>
#include <drm/display/drm_dp_helper.h>
#include <drm/display/drm_dp_mst_helper.h>
#include <drm/drm_edid.h>
+#include <drm/drm_of.h>
#include <drm/drm_print.h>
#include <drm/drm_vblank.h>
#include <drm/drm_panel.h>
@@ -3891,3 +3893,133 @@ int drm_panel_dp_aux_backlight(struct drm_panel *panel, struct drm_dp_aux *aux)
EXPORT_SYMBOL(drm_panel_dp_aux_backlight);
#endif
+
+#if IS_ENABLED(CONFIG_TYPEC)
+static int drm_dp_register_mode_switch(struct device *dev, struct device_node *node,
+ struct drm_dp_typec_switch_desc *switch_desc,
+ void *data, void *mux_set)
+{
+ struct drm_dp_typec_port_data *port_data;
+ struct typec_mux_desc mux_desc = {};
+ char name[32];
+ u32 dp_lanes[2];
+ int ret, num_lanes, port_num = -1;
+
+ num_lanes = drm_of_get_data_lanes_count(node, 0, 2);
+ if (num_lanes <= 0) {
+ dev_err(dev, "Error on getting data lanes count: %d\n",
+ num_lanes);
+ return num_lanes;
+ }
+
+ ret = of_property_read_u32_array(node, "data-lanes", dp_lanes, num_lanes);
+ if (ret) {
+ dev_err(dev, "Failed to read the data-lanes variable: %d\n",
+ ret);
+ return ret;
+ }
+
+ port_num = dp_lanes[0] / 2;
+
+ port_data = &switch_desc->typec_ports[port_num];
+ port_data->data = data;
+ mux_desc.fwnode = &node->fwnode;
+ mux_desc.drvdata = port_data;
+ snprintf(name, sizeof(name), "%s-%u", node->name, 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;
+}
+
+/**
+ * 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.
+ * Register the endpoint as port 0 if the "data-lanes" property falls in 0/1,
+ * and register it as port 1 if "data-lanes" falls in 2/3.
+ */
+int drm_dp_register_typec_switches(struct device *dev, struct device_node *port,
+ struct drm_dp_typec_switch_desc *switch_desc,
+ void *data, void *mux_set)
+{
+ struct device_node *sw;
+ int ret = 0;
+
+ for_each_child_of_node(port, sw) {
+ if (of_property_read_bool(sw, "mode-switch"))
+ switch_desc->num_typec_switches++;
+ }
+
+ if (!switch_desc->num_typec_switches) {
+ dev_warn(dev, "No Type-C switches node found\n");
+ 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;
+
+ /* Register switches for each connector. */
+ for_each_child_of_node(port, sw) {
+ if (!of_property_read_bool(sw, "mode-switch"))
+ continue;
+ ret = drm_dp_register_mode_switch(dev, sw, switch_desc, data, mux_set);
+ if (ret) {
+ dev_err(dev, "Failed to register mode switch: %d\n", ret);
+ of_node_put(sw);
+ break;
+ }
+ }
+
+ if (ret)
+ 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)
+{
+ 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);
+#else
+void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc)
+{
+}
+EXPORT_SYMBOL(drm_dp_register_typec_switches);
+int drm_dp_register_typec_switches(struct device *dev, struct device_node *port,
+ struct drm_dp_typec_switch_desc *switch_desc,
+ void *data, void *mux_set)
+{
+ return 0;
+}
+EXPORT_SYMBOL(drm_dp_unregister_typec_switches);
+#endif
@@ -763,4 +763,20 @@ 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;
+ void *data;
+ bool dp_connected;
+};
+
+struct drm_dp_typec_switch_desc {
+ int num_typec_switches;
+ struct drm_dp_typec_port_data *typec_ports;
+};
+
+void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc);
+int drm_dp_register_typec_switches(struct device *dev, struct device_node *port,
+ struct drm_dp_typec_switch_desc *switch_desc,
+ void *data, void *mux_set);
+
#endif /* _DRM_DP_HELPER_H_ */