From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6E0F4499F14; Mon, 14 Sep 2026 18:14:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789409658; cv=none; b=u8BSAtPxckX96rw9jL52oi/Z+hxcrjnoLNLFGwmbHDS2ZAuF40U/MWFWoCjKVlpEvccuV7fsOJssmvkFMZlapRKq28Y7A+saIS3TprRTXmZsrzJXebQfauFpsEogdPRgdq8pwufsedHarv2RS64z5m572VKige4Vl3slLw5aqlM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789409658; c=relaxed/simple; bh=Her6yhG8c/Pu9YromXbt/KuJgoEzdzspjxJpC/NhJbk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=H38FeY70qqJKX5RW4taSUIbBXc9HiAeg3a3FPy/FGxVLD90v/Uc+zJFSbw5gblOp+FSVMMQ8W50h942JiJkI7/BQtyTiJU2ZMq/fih0S2CLKEF6b8ccuAiTceJAShVv6fC3Ld5jPwPapTr/W2u3D0KCrmFL5UjJGYlMgTCEQvLg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=uJS3ewsv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="uJS3ewsv" Received: by smtp.kernel.org (Postfix) with ESMTPS id F116DC4AF09; Mon, 14 Sep 2026 18:14:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1789409658; bh=Her6yhG8c/Pu9YromXbt/KuJgoEzdzspjxJpC/NhJbk=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=uJS3ewsvBANIlj5aylRX+D11xbZ/Q8vudEhviW73tsr5p+1tdXwLoKfuXKhHnTaQA xSw9z8V0chQiGiAOB2XxpaTd+F3ZXzV8rBFiHj0TK/mv7WXRS5KWGVBAvXAFmKXR+b RYFxSXCW9+ocGsPMxCpt5WjbohC5ug+MnKzlPtxk/a2vgBpkn5Gk0HPvTW2wl74dqp JAac+TIJN2PtopfjO/YEe7CA9fxOKmoZxVsmAKixitnkIJ6JyPO4wwAjiUTJ6YiFbW YyJmPGXNY4zUUKM1cyfSZWCcifUG0m+KTj9HPH8UuWoTzlJ/b7U1haqkANxd2GMkFf 4ooN50+U2Vnsw== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id DC932C88E7D; Mon, 14 Sep 2026 18:14:17 +0000 (UTC) From: David Heidelberg via B4 Relay Date: Mon, 14 Sep 2026 20:14:17 +0200 Subject: [PATCH v3 4/4] backlight: qcom-wled: Read back the programmed brightness at probe Precedence: bulk X-Mailing-List: linux-fbdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260914-qcom-wled-backlight-v3-4-d69fe9843841@ixit.cz> References: <20260914-qcom-wled-backlight-v3-0-d69fe9843841@ixit.cz> In-Reply-To: <20260914-qcom-wled-backlight-v3-0-d69fe9843841@ixit.cz> To: Lee Jones , Daniel Thompson , Jingoo Han , Helge Deller , Kiran Gunda , Marco Mattiolo , =?utf-8?q?Barnab=C3=A1s_Cz=C3=A9m=C3=A1n?= Cc: linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, phone-devel@vger.kernel.org, Konrad Dybcio , Joel Selvaraj , David Heidelberg X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=6845; i=david@ixit.cz; h=from:subject:message-id; bh=Nidh9qw4K//eY6dG1HyoeNGnuAFJH6nbVwPXrtUb50U=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqqDl4V+pJrmV2561jKJU01TGxU8vgcqrIh5X2a PlsSuXv6ESJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCaqg5eAAKCRBgAj/E00kg ckUyD/4kelPr0O/PIMcfSR+A8dfZvlicHAnRvsnN+cmtuK0OC3QRHLcyZnmSMxYm52OmlJ9g6Bo clOpYrBCRKVkkwqPYtRFTwb76dByJqUHR8uSPhY6YQpWXdLxJqM73lHsgCDC52dxoFs5Vv3DZC8 RvdzYWpI6rDCsQ5vQIWPXWfkLe7z0cORtgAUXYW7ZFV4vHMKXZJy9owHFFcDLMDpHZx6IRM/r/g 3T5vTeFsGj8kX0DgRjBMFiwX6NnYyGCiXCrJ9Jq2/+Vf5ovJv0qcJJvthTagR6Gqs9NswdJI8WL bNoG2P/5Z87z5Lk+DojHqExxLYHnL7S+BNSRrfPmiA1cS/8SXyOgiIW6X2lEjdCxmKVnsb0aF7E YX1RNRn6fmo8ZihYxi6oH17H+fwmq1tE5Dv4Agg3DxDKlOjHhcM1LQ0DQESZOeo126EZBiFqSFx BsKhQy5mew9AMTiDiliXS2mKzwZaVuZqj2HYSuAbgrMuffuL21bvV2ShwAGVexqCgKvgwKbQ7M/ svmTCV+tgboZauA8PxBt6wu6HRfenR11R/RL2f8QK/GW0O5G7zmjCWbsfjIyOXV9RYHjXyc6sOV 3knegkXTvUi1fdGjMaE7wYTKPn3jgWgiLA/9/bQRLfk9HhXQouMTUbrUmSym6c3tbrkZMb/DrnB 7+0Ax2FRYsLpz3w== X-Developer-Key: i=david@ixit.cz; a=openpgp; fpr=D77A09CFEEDC2BBD53A7047460023FC4D3492072 X-Endpoint-Received: by B4 Relay for david@ixit.cz/default with auth_id=355 X-Original-From: David Heidelberg Reply-To: david@ixit.cz From: David Heidelberg Since the previous change wled_probe() seeds wled->brightness from MOD_EN, but with default-brightness rather than the level the hardware is actually driving, so a backlight left lit by the bootloader still visibly steps on the first update, and actual_brightness reports the last value written rather than what the panel shows. Add wled_read_brightness(), which returns 0 when MOD_EN is clear and otherwise reads the brightness register the matching wledN_set_brightness() writes: the first enabled string on WLED3 and WLED4, the selected modulator on WLED5. Use it to seed both wled->brightness and the initial backlight property, and expose it as backlight_ops.get_brightness so that actual_brightness reflects the hardware too. A module that is enabled with the brightness registers at zero, which wled4_setup() and wled_auto_string_detection() can leave behind on a cold boot, now reads back as off. The OVP interrupt is then armed by the first brightness update rather than from probe, which is what happens on every other board where the module starts out disabled. Suggested-by: Konrad Dybcio Assisted-by: LLM Signed-off-by: David Heidelberg --- drivers/video/backlight/qcom-wled.c | 76 +++++++++++++++++++++++++++++++------ 1 file changed, 64 insertions(+), 12 deletions(-) diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c index eb742a6598173..471a0cb2b81f6 100644 --- a/drivers/video/backlight/qcom-wled.c +++ b/drivers/video/backlight/qcom-wled.c @@ -54,17 +54,17 @@ #define WLED3_SINK_REG_SYNC 0x47 #define WLED3_SINK_REG_SYNC_CLEAR 0x00 #define WLED3_SINK_REG_CURR_SINK 0x4f #define WLED3_SINK_REG_CURR_SINK_MASK GENMASK(7, 5) #define WLED3_SINK_REG_CURR_SINK_SHFT 5 /* WLED3 specific per-'string' registers below */ -#define WLED3_SINK_REG_BRIGHT(n) (0x40 + (n * 0x10)) +#define WLED3_SINK_REG_BRIGHT(n) (0x40 + (n * 0x2)) #define WLED3_SINK_REG_STR_MOD_EN(n) (0x60 + (n * 0x10)) #define WLED3_SINK_REG_STR_MOD_MASK BIT(7) #define WLED3_SINK_REG_STR_FULL_SCALE_CURR(n) (0x62 + (n * 0x10)) #define WLED3_SINK_REG_STR_FULL_SCALE_CURR_MASK GENMASK(4, 0) #define WLED3_SINK_REG_STR_MOD_SRC(n) (0x63 + (n * 0x10)) @@ -285,16 +285,60 @@ static int wled5_set_brightness(struct wled *wled, u16 brightness) WLED5_SINK_REG_MOD_A_BRIGHTNESS_LSB : WLED5_SINK_REG_MOD_B_BRIGHTNESS_LSB; rc = regmap_bulk_write(wled->regmap, wled->sink_addr + offset, &v, sizeof(v)); return rc; } +static int wled_read_brightness(struct wled *wled) +{ + u16 addr, mask; + __le16 v; + u32 val; + int rc; + + rc = regmap_read(wled->regmap, wled->ctrl_addr + WLED3_CTRL_REG_MOD_EN, + &val); + if (rc < 0) + return rc; + + if (!(val & WLED3_CTRL_REG_MOD_EN_MASK)) + return 0; + + switch (wled->version) { + case 3: + addr = wled->sink_addr + + WLED3_SINK_REG_BRIGHT(wled->cfg.enabled_strings[0]); + mask = WLED3_SINK_REG_BRIGHT_MAX; + break; + case 4: + addr = wled->sink_addr + + WLED4_SINK_REG_BRIGHT(wled->cfg.enabled_strings[0]); + mask = WLED3_SINK_REG_BRIGHT_MAX; + break; + case 5: + addr = wled->sink_addr + (wled->cfg.mod_sel == MOD_A ? + WLED5_SINK_REG_MOD_A_BRIGHTNESS_LSB : + WLED5_SINK_REG_MOD_B_BRIGHTNESS_LSB); + mask = WLED5_SINK_REG_BRIGHT_MAX_15B; + break; + default: + dev_err(wled->dev, "Invalid WLED version\n"); + return -EINVAL; + } + + rc = regmap_bulk_read(wled->regmap, addr, &v, sizeof(v)); + if (rc < 0) + return rc; + + return min_t(u32, le16_to_cpu(v) & mask, wled->max_brightness); +} + static void wled_ovp_work(struct work_struct *work) { struct wled *wled = container_of(work, struct wled, ovp_work.work); enable_irq(wled->ovp_irq); } static int wled_module_enable(struct wled *wled, int val) @@ -475,16 +519,28 @@ static int wled_update_status(struct backlight_device *bl) wled->brightness = brightness; unlock_mutex: mutex_unlock(&wled->lock); return rc; } +static int wled_get_brightness(struct backlight_device *bl) +{ + struct wled *wled = bl_get_data(bl); + int rc; + + mutex_lock(&wled->lock); + rc = wled_read_brightness(wled); + mutex_unlock(&wled->lock); + + return rc; +} + static int wled4_cabc_config(struct wled *wled, bool enable) { int i, j, rc; u8 val; for (i = 0; i < wled->cfg.num_strings; i++) { j = wled->cfg.enabled_strings[i]; @@ -1646,25 +1702,25 @@ static int wled_configure_ovp_irq(struct wled *wled, if (!wled->brightness) disable_irq(wled->ovp_irq); return 0; } static const struct backlight_ops wled_ops = { .update_status = wled_update_status, + .get_brightness = wled_get_brightness, }; static int wled_probe(struct platform_device *pdev) { struct backlight_properties props; struct backlight_device *bl; struct wled *wled; struct regmap *regmap; - u32 mod_en; u32 val; int rc; regmap = dev_get_regmap(pdev->dev.parent, NULL); if (!regmap) { dev_err(&pdev->dev, "Unable to get regmap\n"); return -EINVAL; } @@ -1728,41 +1784,37 @@ static int wled_probe(struct platform_device *pdev) } INIT_DELAYED_WORK(&wled->ovp_work, wled_ovp_work); val = WLED_DEFAULT_BRIGHTNESS; of_property_read_u32(pdev->dev.of_node, "default-brightness", &val); /* - * The module may already be enabled, either by a bootloader that left - * the backlight lit or by the setup above. Record that, so that the - * first brightness update does not enable an already enabled module, - * and so that the OVP irq is armed from probe rather than from that - * first update. + * The module may already be lit, either by the bootloader or by the + * setup above. Start from what the hardware is driving, so that the + * first brightness update does not step the brightness. */ - rc = regmap_read(wled->regmap, wled->ctrl_addr + WLED3_CTRL_REG_MOD_EN, - &mod_en); + rc = wled_read_brightness(wled); if (rc < 0) return rc; - if (mod_en & WLED3_CTRL_REG_MOD_EN_MASK) - wled->brightness = val; + wled->brightness = rc; rc = wled_configure_short_irq(wled, pdev); if (rc < 0) return rc; rc = wled_configure_ovp_irq(wled, pdev); if (rc < 0) return rc; memset(&props, 0, sizeof(struct backlight_properties)); props.type = BACKLIGHT_RAW; - props.brightness = val; + props.brightness = wled->brightness ?: val; props.max_brightness = wled->max_brightness; bl = devm_backlight_device_register(&pdev->dev, wled->name, &pdev->dev, wled, &wled_ops, &props); platform_set_drvdata(pdev, bl); return PTR_ERR_OR_ZERO(bl); }; -- 2.55.0