From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=148.251.105.195 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794632459; b=u4/MKfCIz46t2SLqIqJC7s/tz4CIPN1PwBvrNors0XLDXZ6GQBYKQ45Lj3JBaC9mevpU 6g0E22mv3QFk6IKBy5nQLjTwFmOxh58NdKOjRslrGgH5FWxilMSvremVVU+EgsJyGCCBX mXZyZqFeH7cASTP8Fk1RL1a4XJ0K6CryFEytkTqTi33Utxq+EQhsfH2MEVWOKcXc4N5WY ns4tkMIIHJGynYeRpzN9OM/4reU+JteIB4w/rytjjeRv6yDJ7MnC7xomcgptZ0eCsVOvy p3NBt3Ic7nBbxo5rLdwAdDJ1Zs4RPZ/sgmBmW3RIv4D7qBkoOGWaJVo4dbyI8OhAiOg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794632459; h=DMARC-Filter:DKIM-Signature:Received:Received:From:Date:Subject: MIME-Version:Content-Type:Content-Transfer-Encoding:Message-Id: References:In-Reply-To:To:Cc:X-Mailer:X-Developer-Signature: X-Developer-Key; bh=IuiYOKD4YLpreD/nLJGrziEMcmfonKY4MY8JFDw5E7k=; b=XnTgxU1viqGKtvUFy+zBD568mEGK4265GSuWINx6Iykmlhj3iYI4U+ItA7lzhy5Lc+ji nwIYCcVC85TWRW+e+6k2Zky1PPfWZsx0G7YCozXB/3S4pn1Zhs4+t4kU9NtEpPCZUOzxU rYlIy6Uyku7mgm13dj1BuJtpLUNxVH6JrnwCOqueFxFHq55sdtcAhoaN4qlqvPIyclgJp dHvSfFBjEFWXGsizu3gxpGvWdi7hrbh+a8NVfSJhcbohm9sV2/Q18PH/oGiMPBZ6lyByc I5PsgkWVscu50Qg3sG/V/Bzi21OJjxZaDoEXvSWaj6/yWgtFJL+aLbroJyEftay1HDw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass header.d=collabora.com header.i=@collabora.com header.a=rsa-sha256 header.s=mail header.b=b0QWyK4f; arc=none smtp.remote-ip=148.251.105.195 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A6440606A32D; Sat, 14 Nov 2026 05:00:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org A6440606A32D Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.a=rsa-sha256 header.s=mail header.b=b0QWyK4f DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1794632456; bh=gVPDlukkMHav3dijaRJZnGw/xEdv0jNsddzU7nlThLs=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=b0QWyK4fZqxYjqzTac6iJikkx3E7WcQRCNd3Tss5HQzOuzUngnFhQLv/G+V37eZw7 yZsWwfBMI9WpBuqQgIBgIHBbCJnU+MPLrdBtwmtyZWF5PxUw6SY4HeMxEaDFQrMbSp Ytmwpl8zlMDcO0CJu8svNY8q2mkAJ/1RkNGsLnIjnOU4QVULacTWQvRmf2JsSwFxVN KXhKK29JY2bHObsux1Kj2yLMoZxcOthNrdP6tQCR/NK6H0EuOKl2tgXN3BLWamKQ9d xKPSi3sdKIepyJofzG4LuXBmtnOKKMZq50TFwhUwwW9BavKcay13oJxkwYEhjERehs lERU7WxzV+Huw== Received: from jupiter.universe (unknown [100.64.1.62]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: sre) by bali.collaboradmins.com (Postfix) with ESMTPSA id 5764417E12E0; Sat, 14 Nov 2026 06:00:56 +0100 (CET) Received: by jupiter.universe (Postfix, from userid 1000) id 10E70480035; Sat, 14 Nov 2026 06:00:56 +0100 (CET) From: Sebastian Reichel Date: Sat, 14 Nov 2026 06:00:37 +0100 Subject: [PATCH v12 04/23] drm/bridge: synopsys: dw-dp: Document missing reset line deassert X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261114-synopsys-dw-dp-improvements-v12-4-d42d3dc5bdd4@collabora.com> References: <20261114-synopsys-dw-dp-improvements-v12-0-d42d3dc5bdd4@collabora.com> In-Reply-To: <20261114-synopsys-dw-dp-improvements-v12-0-d42d3dc5bdd4@collabora.com> To: Sandy Huang , =?utf-8?q?Heiko_St=C3=BCbner?= , Andy Yan , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Rob Herring , Krzysztof Kozlowski , Conor Dooley , David Airlie , Simona Vetter , Dmitry Baryshkov , Luca Ceresoli , Philipp Zabel Cc: Cristian Ciocaltea , Damon Ding , Dmitry Baryshkov , Alexey Charkov , dri-devel@lists.freedesktop.org, linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, kernel@collabora.com, linux-arm-kernel@lists.infradead.org, Sebastian Reichel , Sashiko , Andy Yan X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1659; i=sebastian.reichel@collabora.com; h=from:subject:message-id; bh=gVPDlukkMHav3dijaRJZnGw/xEdv0jNsddzU7nlThLs=; b=owJ4nAFtApL9kA0DAAoB2O7X88g7+poByyZiAGr36wfSqzx2QfkGHKW8EK8uQUKg308joTDPL 4umTdCfrivmXIkCMwQAAQoAHRYhBO9mDQdGP4tyanlUE9ju1/PIO/qaBQJq9+sHAAoJENju1/PI O/qaReQP/1XxlW/jNg3nUvjTtgHCnJ+piAlDVuw9Ow1SV/ZaGAbPW1tHnddufVDtARiBNdGyF7I xS89bBmwPHuCmUaboYdK+HmrI5ZWr25icGs/HP8mzG4XweCPVgvsZZ92VoPtjmiuuqu7C2249om MpEs9oWoXmk57SzkmXJ76RDD0VYR/U8qOpKxRt4dcL+eV0cjxpo5QzxayLe+JJfBiYGjdbl6Qgp 5ohVIyqyEq5z4C7lRoBJN0eh3FuwD6namvjPnwKx2r9U0BFAn2YikAGLsgR9DRlpMWHCCw5+u3Z grjksAunRiTL7pgU5AjGr5FvpTl05hpb+TUvGLg4QD0PKJXaZI1nzBLGwiLwA74wtXPpaPcYJ5H O6dblw36qkXJqDRZV6p9vrP6MZeiTa3bPkDInl7BOCoqcBtJYe7zxuc9D8LmpflvVZ764eMEtN3 97wTNJYVzWlTTAzGuqI3tYGOSVrf/89EJAXdfY4ZRaSyNXwKSYVW9h9r7UYiAfsvvr7FNt4eMK7 VBOyvUBA2p6mK3It1PH2OwzzNQl+2apdII6ZSOxCli3DupBrPI+V1ORmLyPgRvcM3TBdwG5kqor SWm2qR6alwXYmNwdV1HPuowvzpH7wE1aW2NtNRbSCq6/Y7rZ7GjIwHR8tvpnXXpD7u8OURr8nry /bYPIk/KvIWRjSVOKbw82Ew== X-Developer-Key: i=sebastian.reichel@collabora.com; a=openpgp; fpr=EF660D07463F8B726A795413D8EED7F3C83BFA9A If the driver uses devm_reset_control_get_exclusive_deasserted() instead of devm_reset_control_get() and thus automatically deasserts during probe, the SoC will hang when the device is unbound. This does not happen, when runtime PM is being used (not yet supported in mainline), which suggests the power-domain involved requires this reset line to be deasserted. Even with runtime PM there is no guarantee that the power-domain is disabled as it is shared. Considering the power-domain does not have the reset dependency described in DT, document the problem but leave things in the current state until a better solution is found as the reset line is deasserted by default on all supported platforms. Reported-by: Sashiko Reviewed-by: Andy Yan Signed-off-by: Sebastian Reichel --- drivers/gpu/drm/bridge/synopsys/dw-dp.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c index 93d52a76044f..9677f789c986 100644 --- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c +++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c @@ -2091,6 +2091,10 @@ struct dw_dp *dw_dp_probe(struct platform_device *pdev, const struct dw_dp_plat_ return ERR_CAST(dp->hdcp_clk); } + /* + * This reset line is deasserted by default; asserting it hangs the SoC if the + * related power-domain is still active. + */ dp->rstc = devm_reset_control_get(dev, NULL); if (IS_ERR(dp->rstc)) { dev_err_probe(dev, PTR_ERR(dp->rstc), "failed to get reset control\n"); -- 2.53.0