From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (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 C7CA11D63E4 for ; Sat, 3 Oct 2026 21:33:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.251.105.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791063230; cv=none; b=eBoSAmAtWiP2QmenKw6PXuNT1Vi0OGIJFL/P+psYQyyZKflA5+xFS3BpWLO6JrL5KX36fBH+ANMnMz+XLJQXbuiSAOuQhGO0aWv7MiDxBiiUlR3Vvtq9yVxROzuquW762IBIxGQ9SKBa9+roCGO2gJKyg3Yz0VnMc9pggMGn+iw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791063230; c=relaxed/simple; bh=kDXqnGMv+3/dGk6DPxEqeXvBQLgvyQU5ZWM8ZzjXf08=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RBD2eeA7dmAEPSJMXzMxu5VQ9Q86kJoiFkln0pwQ6qul748et4/Vd5uBTMhYtqIH4kZO5IJYoMyuZEptzqy/ATs6J/5l2jcgOICDYQ7vXlct0LkQ/hzJg+OP9METFwYAX5enjmluU415h73pzr2qFAt9V9Eckr+1Jxh0DIIN0Ns= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=OpnIRgT1; arc=none smtp.client-ip=148.251.105.195 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.b="OpnIRgT1" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1791063221; bh=kDXqnGMv+3/dGk6DPxEqeXvBQLgvyQU5ZWM8ZzjXf08=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=OpnIRgT17QQtur0E7ZQ1+4nbWFI2gwCemx/0KapAoxCvcfbqCtyXKndD4Y+fQ/EM4 SqhioB0vXIvFRNbrKcA0akg79VEJVi6YYscqU1hSEo3YXe4L/RHhabOeEzRRi7Ln9i SSh1J8rjqKFZf/dDdmtSXDdNjZE/UwDH0smNer4XqntGgxKFm8IE6xzEgk3EeVzHAh yZGuZF7ayBD43yRIH2gtEJc9jjtZ9y16CZZR9A04TYETZJCc90911F5G3rAO3U0DN+ Bgfn6E9GoboB1gZGX+Oqt9rLkjryemH9M9FvyJ27hT1DtEIMtNPG7c/uZvjHnqzRMN +cXR9cJyjrgLA== Received: from [100.64.0.241] (unknown [100.64.0.241]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange x25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: cristicc) by bali.collaboradmins.com (Postfix) with ESMTPSA id 0716617E022A; Sat, 03 Oct 2026 23:33:40 +0200 (CEST) Message-ID: <3c0dc77b-b692-498e-aed6-aa97d827b2f4@collabora.com> Date: Sun, 4 Oct 2026 00:33:40 +0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/3] phy: hdmi: Add optional FRL TxFFE config options To: Vinod Koul Cc: Neil Armstrong , Manivannan Sadhasivam , Heiko Stuebner , Andy Yan , kernel@collabora.com, linux-phy@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org References: <20260901-hdptx-ffe-v2-0-3a5922c76fc5@collabora.com> <20260901-hdptx-ffe-v2-1-3a5922c76fc5@collabora.com> Content-Language: en-US From: Cristian Ciocaltea In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Vinod, On 10/3/26 11:39 PM, Vinod Koul wrote: > On 01-09-26, 22:55, Cristian Ciocaltea wrote: >> During HDMI 2.1 FRL link training, the source and sink can negotiate a >> Transmitter Feed-Forward Equalization (TxFFE) level to improve the >> signal quality. Starting from zero, the source may increment the TxFFE >> level up to a maximum agreed during the LTS3 stage if the sink keeps >> reporting FLT failures. TxFFE adjustment is optional and only attempted >> when both the source and the connected sink support it. >> >> Since the existing HDMI PHY configuration API covers the FRL rate/lane >> selection only, provide the following fields to the frl sub-struct of >> phy_configure_opts_hdmi: >> >> * ffe_level: the TxFFE level to apply, only meaningful when >> set_ffe_level is set. >> >> * set_ffe_level: a 1-bit flag that changes the semantics of the >> phy_configure() call, i.e. when set, the PHY driver must apply the new >> ffe_level and ignore the other frl related fields. > > The ffe_level 0 implies it is disabled, so why should we use a flag for > this? Rather use if value valid (non zero) logic to apply..? That's not quite possible because level 0 is valid (and the default) according to HDMI 2.1 spec. The source is expected to reset TxFFE to default whenever a new FRL rate is set, hence the API shall be conformant. Regards, Cristian