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Message-ID: <CAA8EJpqFuhAtTaTJNMmfaQoYaKF_t6N2QMgbOS1c9XVey8Jf3w@mail.gmail.com>
Date: Thu, 23 Mar 2023 00:38:49 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Pin-yen Lin <treapking@...omium.org>
Cc: Andrzej Hajda <andrzej.hajda@...el.com>,
Neil Armstrong <neil.armstrong@...aro.org>,
Robert Foss <rfoss@...nel.org>,
Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
Jonas Karlman <jonas@...boo.se>,
Jernej Skrabec <jernej.skrabec@...il.com>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Daniel Scally <djrscally@...il.com>,
Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
Sakari Ailus <sakari.ailus@...ux.intel.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J . Wysocki" <rafael@...nel.org>,
Prashant Malani <pmalani@...omium.org>,
Benson Leung <bleung@...omium.org>,
Guenter Roeck <groeck@...omium.org>,
Xin Ji <xji@...logixsemi.com>, linux-kernel@...r.kernel.org,
Thomas Zimmermann <tzimmermann@...e.de>,
linux-acpi@...r.kernel.org,
Javier Martinez Canillas <javierm@...hat.com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com>,
Hsin-Yi Wang <hsinyi@...omium.org>,
Lyude Paul <lyude@...hat.com>,
Nícolas F . R . A . Prado
<nfraprado@...labora.com>, Allen Chen <allen.chen@....com.tw>,
dri-devel@...ts.freedesktop.org, Marek Vasut <marex@...x.de>,
Stephen Boyd <swboyd@...omium.org>,
chrome-platform@...ts.linux.dev, devicetree@...r.kernel.org,
Andi Shyti <andi.shyti@...ux.intel.com>,
Douglas Anderson <dianders@...omium.org>,
Imre Deak <imre.deak@...el.com>,
Jani Nikula <jani.nikula@...el.com>,
Linus Walleij <linus.walleij@...aro.org>,
YueHaibing <yuehaibing@...wei.com>
Subject: Re: [PATCH v14 03/10] drm/display: Add Type-C switch helpers
On Wed, 22 Mar 2023 at 12:47, Pin-yen Lin <treapking@...omium.org> 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.
>
> Signed-off-by: Pin-yen Lin <treapking@...omium.org>
>
> ---
>
> Changes in v14:
> - Introduce a new Kconfig becuase it didn't build when CONFIG_TYPEC=m
> - Add comments about devm_* usage
> - Fix style issues
>
> 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/Kconfig | 8 ++
> drivers/gpu/drm/display/Makefile | 2 +
> drivers/gpu/drm/display/drm_dp_typec_helper.c | 105 ++++++++++++++++++
> include/drm/display/drm_dp_helper.h | 46 ++++++++
> 4 files changed, 161 insertions(+)
> create mode 100644 drivers/gpu/drm/display/drm_dp_typec_helper.c
>
> diff --git a/drivers/gpu/drm/display/Kconfig b/drivers/gpu/drm/display/Kconfig
> index 09712b88a5b8..d61076947a1c 100644
> --- a/drivers/gpu/drm/display/Kconfig
> +++ b/drivers/gpu/drm/display/Kconfig
> @@ -29,6 +29,14 @@ config DRM_DISPLAY_HDMI_HELPER
> help
> DRM display helpers for HDMI.
>
> +config DRM_DISPLAY_DP_TYPEC_HELPER
> + bool
> + default y
> + depends on DRM_DISPLAY_HELPER
> + depends on DRM_DISPLAY_HELPER=TYPEC || TYPEC=y
If it is a select'able option, it doesn't make sense to use "depends"
here. Select will override depends.
> + help
> + DRM display helpers for USB Type-C Displayport Alternate mode.
> +
> config DRM_DP_AUX_CHARDEV
> bool "DRM DP AUX Interface"
> depends on DRM && DRM_DISPLAY_HELPER
> diff --git a/drivers/gpu/drm/display/Makefile b/drivers/gpu/drm/display/Makefile
> index 17ac4a1006a8..2202a6aea38e 100644
> --- a/drivers/gpu/drm/display/Makefile
> +++ b/drivers/gpu/drm/display/Makefile
> @@ -8,6 +8,8 @@ drm_display_helper-$(CONFIG_DRM_DISPLAY_DP_HELPER) += \
> drm_dp_helper.o \
> drm_dp_mst_topology.o \
> drm_dsc_helper.o
> +drm_display_helper-$(CONFIG_DRM_DISPLAY_DP_TYPEC_HELPER) += \
> + drm_dp_typec_helper.o
> drm_display_helper-$(CONFIG_DRM_DISPLAY_HDCP_HELPER) += drm_hdcp_helper.o
> drm_display_helper-$(CONFIG_DRM_DISPLAY_HDMI_HELPER) += \
> drm_hdmi_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..1562a9ccdaf2
> --- /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];
Why 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);
I think it makes more sense to use dev_name here instead of fwnode.
> + mux_desc.name = name;
> + mux_desc.set = mux_set;
> +
> + 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;
> +}
> +
> +/**
> + * 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. This function uses devm_kcalloc
> + * to allocate memory, so it is expected to only call this in the driver probe
> + * functions.
> + *
> + * 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..0fe56586d7bc 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;
> +}
> +
> +#ifdef CONFIG_DRM_DISPLAY_DP_TYPEC_HELPER
> +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_ */
> --
> 2.40.0.rc1.284.g88254d51c5-goog
>
--
With best wishes
Dmitry
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