Messages in this thread | | | Date | Thu, 12 Jan 2023 07:50:10 +0200 | Subject | Re: [PATCH v10 3/9] drm/display: Add Type-C switch helpers | From | Dmitry Baryshkov <> |
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On 12/01/2023 07:48, Pin-yen Lin wrote: > On Thu, Jan 12, 2023 at 1:24 PM Dmitry Baryshkov > <dmitry.baryshkov@linaro.org> wrote: >> >> On 12/01/2023 07:19, Pin-yen Lin wrote: >>> Hi Dmitry, >>> >>> Thanks for the review. >>> >>> On Thu, Jan 12, 2023 at 12:40 PM Dmitry Baryshkov >>> <dmitry.baryshkov@linaro.org> wrote: >>>> >>>> On 12/01/2023 06:20, 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. >>>>> >>>>> Signed-off-by: Pin-yen Lin <treapking@chromium.org> >>>>> Tested-by: Chen-Yu Tsai <wenst@chromium.org> >>>>> Reviewed-by: Chen-Yu Tsai <wenst@chromium.org> >>>>> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> >>>>> >>>>> --- >>>>> >>>>> 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/drm_dp_helper.c | 134 ++++++++++++++++++++++++ >>>>> include/drm/display/drm_dp_helper.h | 17 +++ >>>>> 2 files changed, 151 insertions(+) >>>>> >>>>> diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c >>>>> index 16565a0a5da6..a2ec40a621cb 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 +3893,135 @@ 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, 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 dp_lanes[2]; >>>>> + int ret, num_lanes, port_num = -1; >>>>> + >>>>> + num_lanes = drm_of_get_data_lanes_count(node, 0, 2); >>>> >>>> 2 looks incorrect. IIRC DP altmode can support up to 4 lanes. >>> >>> This function is implemented for 4-lane DP bridges to switch its >>> outputs between 2 downstreams. So, I assume that there will only be at >>> most 2 lanes for each downstream. I don't think a 4-lane downstream >>> makes sense for mode switches unless we want to support bridges with >>> more than 4 lanes. >> >> Yes. However by using 4 here you'd make the helper generic and cover >> both your case and the generic case. We don't need this for the msm case >> (since the mux is handled by the PHY). But if not for the PHY, I'd have >> used such helper (with max_lanes = 4). >> > I wonder if simply using 4 here really makes it more generic here. > This function assumes the mapping between "data-lanes" and the port > number (e.g., 0/1 --> port 0) and hard-coded the way to parse the > property. > > Is it better to use "reg" instead of "data-lanes" to determine the > port number? The drivers can still read the DT node to get the > "data-lanes" property if they want to do some fancy stuffs around > that.
Yes, I admit, this sounds more logical.
>>>> >>>>> + if (num_lanes <= 0) { >>>>> + dev_err(dev, "Error on getting data lanes count from %s: %d\n", >>>>> + node->name, 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 from %s: %d\n", >>>>> + node->name, 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; >>>>> + } >>>>> + >>>>> + 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. >>>>> + * 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, typec_mux_set_fn_t 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_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_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) >>>>> + 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; >>>>> +} >>>>> +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, typec_mux_set_fn_t mux_set) >>>>> +{ >>>>> + return 0; >>>>> +} >>>>> +EXPORT_SYMBOL(drm_dp_unregister_typec_switches); >>>>> +#endif >>>>> diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h >>>>> index ab55453f2d2c..5a3824f13b4e 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 +764,20 @@ 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, typec_mux_set_fn_t mux_set); >>>>> + >>>>> #endif /* _DRM_DP_HELPER_H_ */ >>>> >>>> -- >>>> With best wishes >>>> Dmitry >>>> >>> >>> Best regards, >>> Pin-yen >> >> -- >> With best wishes >> Dmitry >> > Best regards, > Pin-yen
-- With best wishes Dmitry
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