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Message-ID: <CAGXv+5GS5Bj1hzbUEP340FU4yYmEVf4wyNd2B_HEUAMz3OKw6A@mail.gmail.com>
Date: Mon, 9 Jan 2023 19:33:22 +0800
From: Chen-Yu Tsai <wenst@...omium.org>
To: Pin-yen Lin <treapking@...omium.org>
Cc: Andrzej Hajda <andrzej.hajda@...el.com>,
Neil Armstrong <neil.armstrong@...aro.org>,
Robert Foss <robert.foss@...aro.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>,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
Marek Vasut <marex@...x.de>, chrome-platform@...ts.linux.dev,
Javier Martinez Canillas <javierm@...hat.com>,
linux-acpi@...r.kernel.org, devicetree@...r.kernel.org,
Kees Cook <keescook@...omium.org>,
Nícolas F . R . A . Prado
<nfraprado@...labora.com>, Jani Nikula <jani.nikula@...el.com>,
Allen Chen <allen.chen@....com.tw>,
Stephen Boyd <swboyd@...omium.org>,
Hsin-Yi Wang <hsinyi@...omium.org>,
Xin Ji <xji@...logixsemi.com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com>,
Douglas Anderson <dianders@...omium.org>,
Thomas Zimmermann <tzimmermann@...e.de>
Subject: Re: [PATCH v9 3/9] drm/display: Add Type-C switch helpers
On Mon, Jan 9, 2023 at 6:10 PM Chen-Yu Tsai <wenst@...omium.org> wrote:
>
> On Mon, Jan 9, 2023 at 4:41 PM 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 "data-lanes" properties are available in Device Tree.
> >
> > Signed-off-by: Pin-yen Lin <treapking@...omium.org>
>
> Tested-by: Chen-Yu Tsai <wenst@...omium.org>
>
> on MT8192 based Hayato (ASUS Chromebook Flip CM3200).
>
> > ---
> >
> > (no changes since v8)
> >
> > 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/drm_dp_helper.c | 132 ++++++++++++++++++++++++
> > include/drm/display/drm_dp_helper.h | 16 +++
> > 2 files changed, 148 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
> > index 16565a0a5da6..fb9e23744c08 100644
> > --- a/drivers/gpu/drm/display/drm_dp_helper.c
> > +++ b/drivers/gpu/drm/display/drm_dp_helper.c
> > @@ -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_REACHABLE(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)
Using "typec_mux_set_fn_t" instead of "void *" for mux_set would be
more explicit. Same for all the other instances where this parameter
gets declared.
ChenYu
> > +{
> > + 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);
>
> Also printing out the full node name (endpoint@N) would be more helpful.
>
> > + 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);
>
> Same here.
>
> > + 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;
> > +
> > + 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");
>
> Maybe change this to dev_info or even dev_debug? A warning would be too
> noisy if the bridge drivers are calling this helper unconditionally.
>
> Otherwise,
>
> Reviewed-by: Chen-Yu Tsai <wenst@...omium.org>
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