From nobody Tue Sep 29 09:09:02 2026 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 70E683B47E2; Mon, 10 Aug 2026 09:55:43 +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=1786355743; cv=none; b=o4EGGe4A6X/sEZhuOsZtgXhWJ1Eym7+HJoDnxVtGmTP+GAKJk4VyBj9QJfvGdUi1KlD56YwIW37jhuNbgnJ9FJGbYI7umtgxVyTuILA2+s7Xl/bEgLfETTj4+/6kNhJwM2Q74+Y2X93DMIDcwAW0ZjiZxBwfi5vQTclL7IIXClM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786355743; c=relaxed/simple; bh=lRKV8H74Co2qH7BGcr2cTswTqZvkze7IH7Sbt/O3Weg=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=E/thhCWXfdYCWyh7U2HjcdiHbz6IOmjZxxKmCnfTmXmmxXgNh6mxcj/fz5fm0GpndfoXAbz3zpclgOwnRJTVbFwkrbl8EK8l/OmQK8npJ9QC8G9ON2lFgad+eSl87B4nvXJ1tp+ufY18KrXFKpoWNDuUVl4TLLhFeqE1Xo8IKec= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HgnS7ODo; 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="HgnS7ODo" Received: by smtp.kernel.org (Postfix) with ESMTPS id A513EC19425; Mon, 10 Aug 2026 09:55:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1786355742; bh=lRKV8H74Co2qH7BGcr2cTswTqZvkze7IH7Sbt/O3Weg=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=HgnS7ODoDhTe+xdr8JMh+UR7U8ZRkEyTBrtJyyKHlI9fb28qnikx4JhUmKSCvN9Oe A0oC3WtThVDIgNNamDH2j/ko7/4WUinlhBmczWxGY474B9AZMFo0WU8W149DA5bhj0 yEtwS2cpT+DCF5sGSEPPdqzs3KjggbqoDZv11sdr2JrGdcf0Sck1E96ZTUgJB/gIS4 SLeBTBnqq0tYDAepf/Ku94mbJT96Tk8PEGn1dH4QMqCN1WKu7jlUuXpXMJaj/tJFRm +L5slBEkQl/scsDwjA24DqwtPlWB4CNO20kdoijVjPjdDAB7bJ8R97d3IHbosraaBz hD8ZWoOZNw/zw== 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 87031C5AD4E; Mon, 10 Aug 2026 09:55:42 +0000 (UTC) From: David Heidelberg via B4 Relay Date: Mon, 10 Aug 2026 11:55:37 +0200 Subject: [PATCH v2 1/2] drm/panel: lg-sw43408: do not assert reset across unprepare Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260810-fix-blueline-panel-v2-1-9344dfdbc3f9@ixit.cz> References: <20260810-fix-blueline-panel-v2-0-9344dfdbc3f9@ixit.cz> In-Reply-To: <20260810-fix-blueline-panel-v2-0-9344dfdbc3f9@ixit.cz> To: Sumit Semwal , Casey Connolly , Neil Armstrong , Jessica Zhang , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Dmitry Baryshkov , Marijn Suijten , Vinod Koul Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, phone-devel@vger.kernel.org, David Heidelberg X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=2520; i=david@ixit.cz; h=from:subject:message-id; bh=di2OzEU0PRnOGKu5XRkp3UwJDiN4YcH6Uzw5Ht/qTmo=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqeaAcmfWFxH/vXpRpVSRZ7tC+z5dEZIMfcu5sL pQk4pwKikOJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCanmgHAAKCRBgAj/E00kg cimrEACOKggloVunUqSkYEPAHQr9QpRUmDqwumRVhly4Re0KbUuKUFJp0AsDuvTWwtxd53PtnRg IOlbZckmFq2U/CXxSa/cPs7dlDe3dUs9PqKONnGQ793Wg+P0eTtBCVdHvYS1kivf931dtcbvkU5 skzV5687haaSbffYyDXc9ZD6zD4NV8KZ4cmFVA2CoNVxRCbdbr8XdaC+OKdtu7k9E2OQ9iMt+Sc 22OpDEg5Uvjxxp9wn0dDIDGKSse5okN2LPgkgbuUwc8TI33kdy8iP4fiQOc+/CLue7NWvDJXHMX UypepwnQXyUgtUzD0QE8JTysjFdnzexKJKvl0F1kaIxMOUm9yfkvq0mJxq+tPQGZviaTh2MpoL7 Zojo5Nf3shniVfa1m5z6pjQl2GHQVQ/FVtL4xUeSYW9gf8rKYLlTopdIYoHcmDXCygcTFtKoq/X Q5KUQof/hwkyhOfhuyvEHRbn94HRhn7EOc9+eXk793a7dsPxMM2aJRhtcV7g1JcU9jDYSDrolMd hpbxW2dsSACH2OZ4uGKJ6WHqaPVkuXDRlJR3c7BqQtPSR28pNLI68MIWT68yL1FcRKv2VW/hB2P 1L97kPJQ7dhxysOpb2dRrRHWWmpZw9xlX8HLHHzEhrswoGvIBUNEjRCLV37NXSn4/WXBmgzg0a/ CUNK+ROeb9jAxzQ== 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 Asserting the reset GPIO in unprepare() and leaving it asserted puts the DDIC into a state it never recovers from: after the following prepare() the panel answers all DCS commands, reports display-on with clean self-diagnostics, and its configuration registers read back identical to a working panel, but it never lights up again. On the Pixel 3, vddi is shared with the touchscreen controller and remains powered while the panel is off, so with this driver the DDIC sits in reset with its logic rail up for the whole blank period - a state the vendor stack never creates: the vendor firmware only toggles reset as part of a full power-on sequence, and the vendor OS never power-cycles the panel at all (LP mode is used instead). Leave reset alone in unprepare(); prepare() performs the regular reset sequence anyway. Without this, the Pixel 3 display never comes back after the first blank/unblank cycle. Since there isn't any other panel or device using this DDIC, this approach seems resoanble to address the issue. Fixes: 069a6c0e94f9 ("drm: panel: Add LG sw43408 panel driver") Reviewed-by: Neil Armstrong Signed-off-by: David Heidelberg --- drivers/gpu/drm/panel/panel-lg-sw43408.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/panel/panel-lg-sw43408.c b/drivers/gpu/drm/pan= el/panel-lg-sw43408.c index 293826c5006b9..0bf8e08f10b9c 100644 --- a/drivers/gpu/drm/panel/panel-lg-sw43408.c +++ b/drivers/gpu/drm/panel/panel-lg-sw43408.c @@ -50,18 +50,24 @@ static int sw43408_unprepare(struct drm_panel *panel) int ret; =20 mipi_dsi_dcs_set_display_off_multi(&ctx); =20 mipi_dsi_dcs_enter_sleep_mode_multi(&ctx); =20 mipi_dsi_msleep(&ctx, 100); =20 - gpiod_set_value(sw43408->reset_gpio, 1); - + /* + * Keep reset deasserted: vddi may stay powered (it is shared with + * the touchscreen on Pixel 3) and holding the DDIC in reset while + * its logic rail is up puts it into a state that no init sequence + * recovers from - the panel keeps answering DCS commands and + * reports display-on, but never lights up again. The vendor stack + * only ever toggles reset as part of a powered-up init sequence. + */ ret =3D regulator_bulk_disable(ARRAY_SIZE(sw43408_supplies), sw43408->sup= plies); =20 return ret ? : ctx.accum_err; } =20 static int sw43408_program(struct drm_panel *panel) { struct sw43408_panel *sw43408 =3D to_panel_info(panel); --=20 2.55.0 From nobody Tue Sep 29 09:09:02 2026 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 6EB333B47D9; Mon, 10 Aug 2026 09:55:43 +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=1786355743; cv=none; b=Trwy/rA2lmfx+YPZIwUeq02xp8RFpCIaNC2GboXosAYjoqcj8/Zf3SjXodalumF3gin2cGTdMH8m5v6yzh9kJQ4rMWsGsxomDikotJrvBY2Spo80jb0xy4O9K8VtAbztbFec8Mn7mzu38rDewJKCucoaylNCoagliHGglVVlR0M= ARC-Message-Signature: i=1; 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b=BdlyOso0B4McvQe/cnE6EKBioXOJ9NbJmPHbvkJD+1ErZcu+JO+Mm6kGykBocjG5H Uohucq5kVHxSkeYwcGKq1VdoJuClgf9Kk57Q889MB/IbXmnyBjinPu6aC9Hwc1CrLS 530K4I8ffS4Ab6tiO993d3DfYLZrqG//vv7pKjV0g3ixH1kEW4LceDa05jEKndUaHU fAITzLm6hAjo8lgYQvCbrsRUgWYvFLnMnC78x97KO7xSpeR2AVcvrGDETHmpnwkTGS j9Sn129ZYPgZcJWkByS9kHurJJ3BtNf8jD22fD7HDTiF2XRltfSM6Z6kTMibu3yFEe d/WD16sV3P9eQ== 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 9F34DC5AC82; Mon, 10 Aug 2026 09:55:42 +0000 (UTC) From: David Heidelberg via B4 Relay Date: Mon, 10 Aug 2026 11:55:38 +0200 Subject: [PATCH v2 2/2] drm/panel: lg-sw43408: use the full DCS brightness range Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260810-fix-blueline-panel-v2-2-9344dfdbc3f9@ixit.cz> References: <20260810-fix-blueline-panel-v2-0-9344dfdbc3f9@ixit.cz> In-Reply-To: <20260810-fix-blueline-panel-v2-0-9344dfdbc3f9@ixit.cz> To: Sumit Semwal , Casey Connolly , Neil Armstrong , Jessica Zhang , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Dmitry Baryshkov , Marijn Suijten , Vinod Koul Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, phone-devel@vger.kernel.org, David Heidelberg X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=1395; i=david@ixit.cz; h=from:subject:message-id; bh=scglJ6aSldaji48JvrBM5A5u97auNkDSvGSlJqKRe5k=; b=owEBbQKS/ZANAwAIAWACP8TTSSByAcsmYgBqeaAc3VgRZEOaTM54OKlXYIzYbhoEhA65NKcDg 1Hc3lGC9UaJAjMEAAEIAB0WIQTXegnP7twrvVOnBHRgAj/E00kgcgUCanmgHAAKCRBgAj/E00kg cg7OD/40s8ISIFOnNA0G1UHYJYr6xaE0We5PGFZzosOsifznr43Ec3S+ss3FAnXBQ69OX8RTwVs kJb+U1thvNoo9EDrtBgyvaBZrGGSYyjxo9VmtLgytOxVi482WD3RG4LuZkgaWu81GUDwZ9zYSVy NO4/xXC3HARtYloGwunPGDZHOhOiz3iC+qScKC6ccLtUKa3jApxVtzMspF4rrIQQxJ2d+e6NNGV gokA/gVp71z/tNSNCv1vftLCqn/nji/w/Iq7iJEi+7QdMhQyMdN94H9Jz5/Pf7gdl07F/tz8GCz MJdsjurpIJbesWJhUNuy7nhnjGQw3g7YSOsHSrFPwuJSRSfzh4EIVzy9G168FdLV6WVuChMhLx5 bp0kQHbgrafoO1jtErlieC6lncLujZQt4MqORy2SD346WkN0cgWiFMREJPGBoBWcPgJxBjEXKaa mVTlnbJJThZ6SM81TKPVBjwouCw6auCzBwKpFmGr3do+kg7a+AICrGrcbKijzQTi2XYC58kVkV8 gK5XqCPRd5Cf8XA2GCSk4eZvVzomoul2uVz0F+ReyHpOdZelZI84QLXtHMS9yOOe6OhIsTKn4PF cXaXsNGbwJVrGhDCEBHxjx87SEKxH2BIGrrFgHM5QHH7A86C2Bokwea9FARk28AgNI2q9NF/T4/ ilWGZFgvrZMA/7Q== 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 The vendor firmware panel configuration (XBL DisplayDxe panel XML) declares DCSMaxBrightness 0x332 with a two-byte brightness command, and the driver already sends two bytes via mipi_dsi_dcs_set_display_brightness_large(). Capping max_brightness at 255 therefore limits the panel to ~31% of its real brightness range. Use the firmware maximum. Fixes: 069a6c0e94f9 ("drm: panel: Add LG sw43408 panel driver") Signed-off-by: David Heidelberg Reviewed-by: Neil Armstrong --- drivers/gpu/drm/panel/panel-lg-sw43408.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/panel/panel-lg-sw43408.c b/drivers/gpu/drm/pan= el/panel-lg-sw43408.c index 0bf8e08f10b9c..be132b65b0c13 100644 --- a/drivers/gpu/drm/panel/panel-lg-sw43408.c +++ b/drivers/gpu/drm/panel/panel-lg-sw43408.c @@ -203,17 +203,17 @@ static const struct backlight_ops sw43408_backlight_o= ps =3D { }; =20 static int sw43408_backlight_init(struct sw43408_panel *ctx) { struct device *dev =3D &ctx->link->dev; const struct backlight_properties props =3D { .type =3D BACKLIGHT_PLATFORM, .brightness =3D 255, - .max_brightness =3D 255, + .max_brightness =3D 818, }; =20 ctx->base.backlight =3D devm_backlight_device_register(dev, dev_name(dev)= , dev, ctx->link, &sw43408_backlight_ops, &props); =20 if (IS_ERR(ctx->base.backlight)) --=20 2.55.0