From patchwork Thu Apr 30 19:46:12 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 201269 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DBD2C4724C for ; Thu, 30 Apr 2020 19:46:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A64820774 for ; Thu, 30 Apr 2020 19:46:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="XkUJdR8V" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726902AbgD3Tqa (ORCPT ); Thu, 30 Apr 2020 15:46:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54382 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726861AbgD3Tq2 (ORCPT ); Thu, 30 Apr 2020 15:46:28 -0400 Received: from mail-pf1-x442.google.com (mail-pf1-x442.google.com [IPv6:2607:f8b0:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0DBB4C08E859 for ; Thu, 30 Apr 2020 12:46:28 -0700 (PDT) Received: by mail-pf1-x442.google.com with SMTP id x2so373970pfx.7 for ; Thu, 30 Apr 2020 12:46:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=NxGWym6M39FpWdScigAXkwBmrVrNXh+0LWhd39ynj6c=; b=XkUJdR8V1C3am+EJyt9UZIe3TO+QKdIR5fwICpZC4ZHIh7XC6dK2m/2frGsFFmVF4+ XFvFRZDs/uKFuBsrAMBeFg/o5gbGXanTomcJTZ9gpykF5Op/zXbfwstVNm9poKskcXUU D4k5+FuOjdrHtSTiIAZzl4puSjm+lATNc65ww= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=NxGWym6M39FpWdScigAXkwBmrVrNXh+0LWhd39ynj6c=; b=BQ6LjlZgyJ5AuI8LdyUQApYnhIqtuBXE61SulAK1gL2X6MRwm4YqneSrqDQeNapQh3 X7TXh1W6E8qK4EyNZ7cCk75eoRVCSpDpek4or/pUoyh/GpnWqnSNsaNpBlM6PY9+m30S FdtMO3WpOle4rvruRONt0KtnXd1DPnVr026YuNyHpJYwggOXnyPyiGBEzhyitAI/jJDi Hrn2lpg8DD5gjx/coZXz/YwAnzIVSlhdWFOgMxiB1SPtLFNZRChj0MG27EhMFpVwYXF9 wh4BG1oA+oNzjmIkSvhgnS9Kcdf0no9+mDhto4yN8dPsawYPGMh5TIl0xO+Mf+YPpXHc rxPw== X-Gm-Message-State: AGi0PuZv8OUPl51nPMdg+svG9oLVbVGCn2BZeFuBIIGuOgjA7hzYUrMu 9aQayaGAw6sHkvxao9FQFZqYIg== X-Google-Smtp-Source: APiQypI8SL4AfT1E4wyLsRXT6pVJShj3Chcf1e1fcW4Z6r9ohTrqxNdAMX2KVlkj3fEWUtQ5+gqT5Q== X-Received: by 2002:a62:f247:: with SMTP id y7mr387808pfl.200.1588275987416; Thu, 30 Apr 2020 12:46:27 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:1:24fa:e766:52c9:e3b2]) by smtp.gmail.com with ESMTPSA id u3sm495993pfb.105.2020.04.30.12.46.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Apr 2020 12:46:26 -0700 (PDT) From: Douglas Anderson To: linus.walleij@linaro.org, bgolaszewski@baylibre.com, airlied@linux.ie, daniel@ffwll.ch, robh+dt@kernel.org, narmstrong@baylibre.com, a.hajda@samsung.com, Laurent.pinchart@ideasonboard.com, spanda@codeaurora.org Cc: linux-gpio@vger.kernel.org, jonas@kwiboo.se, robdclark@chromium.org, bjorn.andersson@linaro.org, jeffrey.l.hugo@gmail.com, jernej.skrabec@siol.net, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, swboyd@chromium.org, Douglas Anderson , linux-kernel@vger.kernel.org Subject: [PATCH v4 1/6] drm/bridge: ti-sn65dsi86: Export bridge GPIOs to Linux Date: Thu, 30 Apr 2020 12:46:12 -0700 Message-Id: <20200430124442.v4.1.Ia50267a5549392af8b37e67092ca653a59c95886@changeid> X-Mailer: git-send-email 2.26.2.526.g744177e7f7-goog In-Reply-To: <20200430194617.197510-1-dianders@chromium.org> References: <20200430194617.197510-1-dianders@chromium.org> MIME-Version: 1.0 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org The ti-sn65dsi86 MIPI DSI to eDP bridge chip has 4 pins on it that can be used as GPIOs in a system. Each pin can be configured as input, output, or a special function for the bridge chip. These are: - GPIO1: SUSPEND Input - GPIO2: DSIA VSYNC - GPIO3: DSIA HSYNC or VSYNC - GPIO4: PWM Let's expose these pins as GPIOs. A few notes: - Access to ti-sn65dsi86 is via i2c so we set "can_sleep". - These pins can't be configured for IRQ. - There are no programmable pulls or other fancy features. - Keeping the bridge chip powered might be expensive. The driver is setup such that if all used GPIOs are only inputs we'll power the bridge chip on just long enough to read the GPIO and then power it off again. Setting a GPIO as output will keep the bridge powered. - If someone releases a GPIO we'll implicitly switch it to an input so we no longer need to keep the bridge powered for it. Because of all of the above limitations we just need to implement a bare-bones GPIO driver. The device tree bindings already account for this device being a GPIO controller so we only need the driver changes for it. NOTE: Despite the fact that these pins are nominally muxable I don't believe it makes sense to expose them through the pinctrl interface as well as the GPIO interface. The special functions are things that the bridge chip driver itself would care about and it can just configure the pins as needed. Signed-off-by: Douglas Anderson Cc: Linus Walleij Cc: Bartosz Golaszewski Reviewed-by: Stephen Boyd --- Changes in v4: - Don't include gpio.h - Use gpiochip_get_data() instead of container_of() to get data. - GPIOF_DIR_XXX => GPIO_LINE_DIRECTION_XXX - Use Linus W's favorite syntax to read a bit from a bitfield. - Define and use SN_GPIO_MUX_MASK. - Add a comment about why we use a bitmap for gchip_output. Changes in v3: - Becaue => Because - Add a kernel-doc to our pdata to clarify double-duty of gchip_output. - More comments about how powering off affects us (get_dir, dir_input). - Cleanup tail of ti_sn_setup_gpio_controller() to avoid one "return". - Use a bitmap rather than rolling my own. Changes in v2: - ("Export...GPIOs") is 1/2 of replacement for ("Allow...bridge GPIOs") drivers/gpu/drm/bridge/ti-sn65dsi86.c | 195 ++++++++++++++++++++++++++ 1 file changed, 195 insertions(+) diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c index 6ad688b320ae..1a125423eb07 100644 --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c @@ -4,9 +4,11 @@ * datasheet: http://www.ti.com/lit/ds/symlink/sn65dsi86.pdf */ +#include #include #include #include +#include #include #include #include @@ -54,6 +56,14 @@ #define BPP_18_RGB BIT(0) #define SN_HPD_DISABLE_REG 0x5C #define HPD_DISABLE BIT(0) +#define SN_GPIO_IO_REG 0x5E +#define SN_GPIO_INPUT_SHIFT 4 +#define SN_GPIO_OUTPUT_SHIFT 0 +#define SN_GPIO_CTRL_REG 0x5F +#define SN_GPIO_MUX_INPUT 0 +#define SN_GPIO_MUX_OUTPUT 1 +#define SN_GPIO_MUX_SPECIAL 2 +#define SN_GPIO_MUX_MASK 0x3 #define SN_AUX_WDATA_REG(x) (0x64 + (x)) #define SN_AUX_ADDR_19_16_REG 0x74 #define SN_AUX_ADDR_15_8_REG 0x75 @@ -88,6 +98,34 @@ #define SN_REGULATOR_SUPPLY_NUM 4 +#define SN_NUM_GPIOS 4 + +/** + * struct ti_sn_bridge - Platform data for ti-sn65dsi86 driver. + * @dev: Pointer to our device. + * @regmap: Regmap for accessing i2c. + * @aux: Our aux channel. + * @bridge: Our bridge. + * @connector: Our connector. + * @debugfs: Used for managing our debugfs. + * @host_node: Remote DSI node. + * @dsi: Our MIPI DSI source. + * @refclk: Our reference clock. + * @panel: Our panel. + * @enable_gpio: The GPIO we toggle to enable the bridge. + * @supplies: Data for bulk enabling/disabling our regulators. + * @dp_lanes: Count of dp_lanes we're using. + * + * @gchip: If we expose our GPIOs, this is used. + * @gchip_output: A cache of whether we've set GPIOs to output. This + * serves double-duty of keeping track of the direction and + * also keeping track of whether we've incremented the + * pm_runtime reference count for this pin, which we do + * whenever a pin is configured as an output. This is a + * bitmap so we can do atomic ops on it without an extra + * lock so concurrent users of our 4 GPIOs don't stomp on + * each other's read-modify-write. + */ struct ti_sn_bridge { struct device *dev; struct regmap *regmap; @@ -102,6 +140,9 @@ struct ti_sn_bridge { struct gpio_desc *enable_gpio; struct regulator_bulk_data supplies[SN_REGULATOR_SUPPLY_NUM]; int dp_lanes; + + struct gpio_chip gchip; + DECLARE_BITMAP(gchip_output, SN_NUM_GPIOS); }; static const struct regmap_range ti_sn_bridge_volatile_ranges[] = { @@ -874,6 +915,154 @@ static int ti_sn_bridge_parse_dsi_host(struct ti_sn_bridge *pdata) return 0; } +static int ti_sn_bridge_gpio_get_direction(struct gpio_chip *chip, + unsigned int offset) +{ + struct ti_sn_bridge *pdata = gpiochip_get_data(chip); + + /* + * We already have to keep track of the direction because we use + * that to figure out whether we've powered the device. We can + * just return that rather than (maybe) powering up the device + * to ask its direction. + */ + return test_bit(offset, pdata->gchip_output) ? + GPIO_LINE_DIRECTION_OUT : GPIO_LINE_DIRECTION_IN; +} + +static int ti_sn_bridge_gpio_get(struct gpio_chip *chip, unsigned int offset) +{ + struct ti_sn_bridge *pdata = gpiochip_get_data(chip); + unsigned int val; + int ret; + + /* + * When the pin is an input we don't forcibly keep the bridge + * powered--we just power it on to read the pin. NOTE: part of + * the reason this works is that the bridge defaults (when + * powered back on) to all 4 GPIOs being configured as GPIO input. + * Also note that if something else is keeping the chip powered the + * pm_runtime functions are lightweight increments of a refcount. + */ + pm_runtime_get_sync(pdata->dev); + ret = regmap_read(pdata->regmap, SN_GPIO_IO_REG, &val); + pm_runtime_put(pdata->dev); + + if (ret) + return ret; + + return !!(val & BIT(SN_GPIO_INPUT_SHIFT + offset)); +} + +static void ti_sn_bridge_gpio_set(struct gpio_chip *chip, unsigned int offset, + int val) +{ + struct ti_sn_bridge *pdata = gpiochip_get_data(chip); + int ret; + + if (!test_bit(offset, pdata->gchip_output)) { + dev_err(pdata->dev, "Ignoring GPIO set while input\n"); + return; + } + + val &= 1; + ret = regmap_update_bits(pdata->regmap, SN_GPIO_IO_REG, + BIT(SN_GPIO_OUTPUT_SHIFT + offset), + val << (SN_GPIO_OUTPUT_SHIFT + offset)); +} + +static int ti_sn_bridge_gpio_direction_input(struct gpio_chip *chip, + unsigned int offset) +{ + struct ti_sn_bridge *pdata = gpiochip_get_data(chip); + int shift = offset * 2; + int ret; + + if (!test_and_clear_bit(offset, pdata->gchip_output)) + return 0; + + ret = regmap_update_bits(pdata->regmap, SN_GPIO_CTRL_REG, + SN_GPIO_MUX_MASK << shift, + SN_GPIO_MUX_INPUT << shift); + if (ret) { + set_bit(offset, pdata->gchip_output); + return ret; + } + + /* + * NOTE: if nobody else is powering the device this may fully power + * it off and when it comes back it will have lost all state, but + * that's OK because the default is input and we're now an input. + */ + pm_runtime_put(pdata->dev); + + return 0; +} + +static int ti_sn_bridge_gpio_direction_output(struct gpio_chip *chip, + unsigned int offset, int val) +{ + struct ti_sn_bridge *pdata = gpiochip_get_data(chip); + int shift = offset * 2; + int ret; + + if (test_and_set_bit(offset, pdata->gchip_output)) + return 0; + + pm_runtime_get_sync(pdata->dev); + + /* Set value first to avoid glitching */ + ti_sn_bridge_gpio_set(chip, offset, val); + + /* Set direction */ + ret = regmap_update_bits(pdata->regmap, SN_GPIO_CTRL_REG, + SN_GPIO_MUX_MASK << shift, + SN_GPIO_MUX_OUTPUT << shift); + if (ret) { + clear_bit(offset, pdata->gchip_output); + pm_runtime_put(pdata->dev); + } + + return ret; +} + +static void ti_sn_bridge_gpio_free(struct gpio_chip *chip, unsigned int offset) +{ + /* We won't keep pm_runtime if we're input, so switch there on free */ + ti_sn_bridge_gpio_direction_input(chip, offset); +} + +static const char * const ti_sn_bridge_gpio_names[SN_NUM_GPIOS] = { + "GPIO1", "GPIO2", "GPIO3", "GPIO4" +}; + +static int ti_sn_setup_gpio_controller(struct ti_sn_bridge *pdata) +{ + int ret; + + /* Only init if someone is going to use us as a GPIO controller */ + if (!of_property_read_bool(pdata->dev->of_node, "gpio-controller")) + return 0; + + pdata->gchip.label = dev_name(pdata->dev); + pdata->gchip.parent = pdata->dev; + pdata->gchip.owner = THIS_MODULE; + pdata->gchip.free = ti_sn_bridge_gpio_free; + pdata->gchip.get_direction = ti_sn_bridge_gpio_get_direction; + pdata->gchip.direction_input = ti_sn_bridge_gpio_direction_input; + pdata->gchip.direction_output = ti_sn_bridge_gpio_direction_output; + pdata->gchip.get = ti_sn_bridge_gpio_get; + pdata->gchip.set = ti_sn_bridge_gpio_set; + pdata->gchip.can_sleep = true; + pdata->gchip.names = ti_sn_bridge_gpio_names; + pdata->gchip.ngpio = SN_NUM_GPIOS; + ret = devm_gpiochip_add_data(pdata->dev, &pdata->gchip, pdata); + if (ret) + dev_err(pdata->dev, "can't add gpio chip\n"); + + return ret; +} + static int ti_sn_bridge_probe(struct i2c_client *client, const struct i2c_device_id *id) { @@ -937,6 +1126,12 @@ static int ti_sn_bridge_probe(struct i2c_client *client, pm_runtime_enable(pdata->dev); + ret = ti_sn_setup_gpio_controller(pdata); + if (ret) { + pm_runtime_disable(pdata->dev); + return ret; + } + i2c_set_clientdata(client, pdata); pdata->aux.name = "ti-sn65dsi86-aux"; From patchwork Thu Apr 30 19:46:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 201267 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1BFFDC47257 for ; 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Thu, 30 Apr 2020 12:46:30 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:1:24fa:e766:52c9:e3b2]) by smtp.gmail.com with ESMTPSA id u3sm495993pfb.105.2020.04.30.12.46.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Apr 2020 12:46:30 -0700 (PDT) From: Douglas Anderson To: linus.walleij@linaro.org, bgolaszewski@baylibre.com, airlied@linux.ie, daniel@ffwll.ch, robh+dt@kernel.org, narmstrong@baylibre.com, a.hajda@samsung.com, Laurent.pinchart@ideasonboard.com, spanda@codeaurora.org Cc: linux-gpio@vger.kernel.org, jonas@kwiboo.se, robdclark@chromium.org, bjorn.andersson@linaro.org, jeffrey.l.hugo@gmail.com, jernej.skrabec@siol.net, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, swboyd@chromium.org, Douglas Anderson , Sam Ravnborg , Thierry Reding , linux-kernel@vger.kernel.org Subject: [PATCH v4 3/6] drm/panel-simple: Support hpd-gpios for delaying prepare() Date: Thu, 30 Apr 2020 12:46:14 -0700 Message-Id: <20200430124442.v4.3.I53fed5b501a31e7a7fa13268ebcdd6b77bd0cadd@changeid> X-Mailer: git-send-email 2.26.2.526.g744177e7f7-goog In-Reply-To: <20200430194617.197510-1-dianders@chromium.org> References: <20200430194617.197510-1-dianders@chromium.org> MIME-Version: 1.0 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org People use panel-simple when they have panels that are builtin to their device. In these cases the HPD (Hot Plug Detect) signal isn't really used for hotplugging devices but instead is used for power sequencing. Panel timing diagrams (especially for eDP panels) usually have the HPD signal in them and it acts as an indicator that the panel is ready for us to talk to it. Sometimes the HPD signal is hooked up to a normal GPIO on a system. In this case we need to poll it in the correct place to know that the panel is ready for us. In some system designs the right place for this is panel-simple. When adding this support, we'll account for the case that there might be a circular dependency between panel-simple and the provider of the GPIO. The case this was designed for was for the "ti-sn65dsi86" bridge chip. If HPD is hooked up to one of the GPIOs provided by the bridge chip then in our probe function we'll always get back -EPROBE_DEFER. Let's handle this by allowing this GPIO to show up late if we saw -EPROBE_DEFER during probe. NOTE: since the gpio_get_optional() is used, if the "hpd-gpios" isn't there our variable will just be NULL and we won't do anything in prepare(). Signed-off-by: Douglas Anderson Reviewed-by: Stephen Boyd Reviewed-by: Linus Walleij --- Changes in v4: None Changes in v3: - Remind how gpio_get_optional() works in the commit message. Changes in v2: - ("simple...hpd-gpios") is 1/2 of replacement for ("Allow...bridge GPIOs") drivers/gpu/drm/panel/panel-simple.c | 53 ++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c index 3ad828eaefe1..f816e2aa29cd 100644 --- a/drivers/gpu/drm/panel/panel-simple.c +++ b/drivers/gpu/drm/panel/panel-simple.c @@ -23,6 +23,7 @@ #include #include +#include #include #include #include @@ -108,6 +109,7 @@ struct panel_simple { struct i2c_adapter *ddc; struct gpio_desc *enable_gpio; + struct gpio_desc *hpd_gpio; struct drm_display_mode override_mode; }; @@ -259,11 +261,37 @@ static int panel_simple_unprepare(struct drm_panel *panel) return 0; } +static int panel_simple_get_hpd_gpio(struct device *dev, + struct panel_simple *p, bool from_probe) +{ + int err; + + p->hpd_gpio = devm_gpiod_get_optional(dev, "hpd", GPIOD_IN); + if (IS_ERR(p->hpd_gpio)) { + err = PTR_ERR(p->hpd_gpio); + + /* + * If we're called from probe we won't consider '-EPROBE_DEFER' + * to be an error--we'll leave the error code in "hpd_gpio". + * When we try to use it we'll try again. This allows for + * circular dependencies where the component providing the + * hpd gpio needs the panel to init before probing. + */ + if (err != -EPROBE_DEFER || !from_probe) { + dev_err(dev, "failed to get 'hpd' GPIO: %d\n", err); + return err; + } + } + + return 0; +} + static int panel_simple_prepare(struct drm_panel *panel) { struct panel_simple *p = to_panel_simple(panel); unsigned int delay; int err; + int hpd_asserted; if (p->prepared) return 0; @@ -282,6 +310,26 @@ static int panel_simple_prepare(struct drm_panel *panel) if (delay) msleep(delay); + if (p->hpd_gpio) { + if (IS_ERR(p->hpd_gpio)) { + err = panel_simple_get_hpd_gpio(panel->dev, p, false); + if (err) + return err; + } + + err = readx_poll_timeout(gpiod_get_value_cansleep, p->hpd_gpio, + hpd_asserted, hpd_asserted, + 1000, 2000000); + if (hpd_asserted < 0) + err = hpd_asserted; + + if (err) { + dev_err(panel->dev, + "error waiting for hpd GPIO: %d\n", err); + return err; + } + } + p->prepared = true; return 0; @@ -462,6 +510,11 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc) panel->desc = desc; panel->no_hpd = of_property_read_bool(dev->of_node, "no-hpd"); + if (!panel->no_hpd) { + err = panel_simple_get_hpd_gpio(dev, panel, true); + if (err) + return err; + } panel->supply = devm_regulator_get(dev, "power"); if (IS_ERR(panel->supply)) From patchwork Thu Apr 30 19:46:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 201268 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4DDF1C4725A for ; Thu, 30 Apr 2020 19:46:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 30737207DD for ; 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Thu, 30 Apr 2020 12:46:33 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:1:24fa:e766:52c9:e3b2]) by smtp.gmail.com with ESMTPSA id u3sm495993pfb.105.2020.04.30.12.46.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Apr 2020 12:46:32 -0700 (PDT) From: Douglas Anderson To: linus.walleij@linaro.org, bgolaszewski@baylibre.com, airlied@linux.ie, daniel@ffwll.ch, robh+dt@kernel.org, narmstrong@baylibre.com, a.hajda@samsung.com, Laurent.pinchart@ideasonboard.com, spanda@codeaurora.org Cc: linux-gpio@vger.kernel.org, jonas@kwiboo.se, robdclark@chromium.org, bjorn.andersson@linaro.org, jeffrey.l.hugo@gmail.com, jernej.skrabec@siol.net, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, swboyd@chromium.org, Douglas Anderson , linux-kernel@vger.kernel.org Subject: [PATCH v4 5/6] dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd Date: Thu, 30 Apr 2020 12:46:16 -0700 Message-Id: <20200430124442.v4.5.I72892d485088e57378a4748c86bc0f6c2494d807@changeid> X-Mailer: git-send-email 2.26.2.526.g744177e7f7-goog In-Reply-To: <20200430194617.197510-1-dianders@chromium.org> References: <20200430194617.197510-1-dianders@chromium.org> MIME-Version: 1.0 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org The ti-sn65dsi86 MIPI DSI to eDP bridge chip has a dedicated hardware HPD (Hot Plug Detect) pin on it, but it's mostly useless for eDP because of excessive debouncing in hardware. Specifically there is no way to disable the debouncing and for eDP debouncing hurts you because HPD is just used for knowing when the panel is ready, not for detecting physical plug events. Currently the driver in Linux just assumes that nobody has HPD hooked up. It relies on folks setting the "no-hpd" property in the panel node to specify that HPD isn't hooked up and then the panel driver using this to add some worst case delays when turning on the panel. Apparently it's also useful to specify "no-hpd" in the bridge node so that the bridge driver can make sure it's doing the right thing without peeking into the panel [1]. This would be used if anyone ever found it useful to implement support for the HW HPD pin on the bridge. Let's add this property to the bindings. NOTES: - This is somewhat of a backward-incompatible change. All current known users of ti-sn65dsi86 didn't have "no-hpd" specified in the bridge node yet none of them had HPD hooked up. This worked because the current Linux driver just assumed that HPD was never hooked up. We could make it less incompatible by saying that for this bridge it's assumed HPD isn't hooked up _unless_ a property is defined, but "no-hpd" is much more standard and it's unlikely to matter unless someone quickly goes and implements HPD in the driver. - It is sensible to specify "no-hpd" at the bridge chip level and specify "hpd-gpios" at the panel level. That would mean HPD is hooked up to some other GPIO in the system, just not the hardware HPD pin on the bridge chip. [1] https://lore.kernel.org/r/20200417180819.GE5861@pendragon.ideasonboard.com Signed-off-by: Douglas Anderson Reviewed-by: Stephen Boyd Reviewed-by: Linus Walleij --- Changes in v4: - Tacked on "or is otherwise unusable." to description. Changes in v3: - useful implement => useful to implement Changes in v2: - ("dt-bindings: drm/bridge: ti-sn65dsi86: Document no-hpd") new for v2. .../devicetree/bindings/display/bridge/ti,sn65dsi86.yaml | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml index 6d7d40ad45ac..75c4e8b8e4b7 100644 --- a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml +++ b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml @@ -28,6 +28,12 @@ properties: maxItems: 1 description: GPIO specifier for GPIO1 pin on bridge (active low). + no-hpd: + type: boolean + description: + Set if the HPD line on the bridge isn't hooked up to anything or is + otherwise unusable. + vccio-supply: description: A 1.8V supply that powers the digital IOs. @@ -207,6 +213,8 @@ examples: clocks = <&rpmhcc RPMH_LN_BB_CLK2>; clock-names = "refclk"; + no-hpd; + ports { #address-cells = <1>; #size-cells = <0>;