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 E04B041F5FC; Mon, 21 Sep 2026 10:46:25 +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=1789987586; cv=none; b=LpEzdYXmtdsO+rhAcIjVlN0qbF0x7eegsFV96R7hQ6tZ6DTaiG7DKlDG+unnjk5K+DYN3kMXI8xa43W9rQi/SFHHsLWAtdRKOCgym1h1UAuAhbGGGmZU2nJPkOSMwHzt2jPs53mc8+9eUT8adpJxW623yzRirahWWUaPFYtT7co= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789987586; c=relaxed/simple; bh=n5z+D92Tf4v9853MGiqmofw4VuQ92a5uY5YoXMvv1HM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=A+nlyJKeiBBvsxeK5eVoD6VC2DCYe8xB6ZzJM0wetF9JEHMMY50domNg7Vr1KDxtJKpp3p/KCk4sPhS5fN3fQgaWDlVFC8YcmPUQIsc+g+wL/UirW3ux4ft1qrycdGJ77UYyAWKm+m0HsJ/X+8+gxjz+E+wa+tknjW+Xtc8TNDA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LdsBzRI0; 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="LdsBzRI0" Received: by smtp.kernel.org (Postfix) with ESMTPS id A8F2DC2BD01; Mon, 21 Sep 2026 10:46:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1789987585; bh=n5z+D92Tf4v9853MGiqmofw4VuQ92a5uY5YoXMvv1HM=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=LdsBzRI0poE8Pac0jEJIHy0xETKGcgs1X8jPzVOnpRfMcsuHEjlyFUlEfsLlUDlCt 5faZuG06K6sLYL6OGHiNsX1YWrAVf2xVLUEqXAn/WdkLwXgOBwOjrCnGDd4Cwu56IA O9mOK5DLy0Ae9IPfVExTbpdu33pimXfmoir++82S/O4ke8aW89N0kww/P/liEWgrBm FCYy/isODMU5FP+UrQrNreRPb8r+vSAgG7g4rKilfxSSq/feA0ZPtzKNbZkgBaJsZa bNQn/v2oMGR02gQfymrJCi/fJXVD8yEXMmOSlMqobbRVQPZOYYNxrbswIvxu9QNZwg 5yyr0peM+B8lA== 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 90C3AC982F1; Mon, 21 Sep 2026 10:46:25 +0000 (UTC) From: David Heidelberg via B4 Relay Date: Mon, 21 Sep 2026 12:46:25 +0200 Subject: [PATCH v4 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: <20260921-qcom-wled-backlight-v4-4-bab8c7ef73cb@ixit.cz> References: <20260921-qcom-wled-backlight-v4-0-bab8c7ef73cb@ixit.cz> In-Reply-To: <20260921-qcom-wled-backlight-v4-0-bab8c7ef73cb@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=6134; i=david@ixit.cz; h=from:subject:message-id; bh=Vd0mK0QtPcwQRIQctDNdJy4/aT9MYS6AbqA9R9Lgs7M=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqsQr/SPXXhzir5slfNf//B0RQVNzZfsL8bCu40 sNHQe0OfyqJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCarEK/wAKCRBgAj/E00kg cohSD/43ZwcZK12PiDRqLFQ1BSQj/qpvka/d9RpoDqvnRgqK4kf2y0NM4dS2TQK/FdW5WZ+/Yi6 y31aalt+YjK/Bq+IGnkO6rBIQHuRhNA6r3pDZKFVV2t0IG8sYVENY97njnDu2/NTvsBQ3UsSv4j pK9l2rU88hLobLSxO1zzEYAUrApOR/ibpYipJ12A7jwGrVUeJNF5eKYaLAudIO7AZv+B7UUms/h ssYYHA8EeTaukyFUvWw8PDd0KJsuEHa8GqolTOJxdQND6CJdl5Lx0Mlg7jWry/2wZZmtxPMjVBR JBZBXFs+8EeMXM9QapCVLV/aIgVeO+xUcOoQbMyQBMauFfXF0e/YDW/PR7Qhk4SlpHW8TMCvPWg ZYbG23sGon4Qo54P9PNe9IAQuwaHXq3eQJWZxkmfL0ExRhPhas0EUGledpjCjvTuiOOSNBnl4jW E6VPMZpoTLa1X5wUymOunEKw1tq8BWTDaw8Ic0mdjY0UhOahKxEhQ9AhiaJxPa9nouVdKZJnGSt rRS1pntI1oWsfwPcJClyNmXPLt51XZygdR1JLCUo65JPn5rqBWvMQLba4eXLY7xSCSKNToM1/2K BJMD71JkHf15/fCsvsPbv1dPF0z71Z2d1YZZTa5AoRBjjg6sTfUal+29YX7AOYBax7jxN95Hlzv F3B9oCckP7WZJdg== 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 | 74 +++++++++++++++++++++++++++++++------ 1 file changed, 63 insertions(+), 11 deletions(-) diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c index 3ce3bade3b8dd..ca350f320e177 100644 --- a/drivers/video/backlight/qcom-wled.c +++ b/drivers/video/backlight/qcom-wled.c @@ -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; } @@ -1729,41 +1785,37 @@ 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); return PTR_ERR_OR_ZERO(bl); }; static void wled_remove(struct platform_device *pdev) -- 2.55.0