From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EE95ACA5FE4 for ; Sat, 3 Oct 2026 21:33:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=lybFAex9WxGAgZ+zpS5TZW8MDwPCoDmGh2YO/5uBlvI=; b=RCjl3Mxvi3iMi37NmAqgyj6/c3 9LKermv+HrxB+Ve5me+gm2+OAnkV+BAtomzx22ZZvf8o57bub9BhIFUICkR7c77kZYCwkM/b4uasD t83OERV5uBXhp+FdwEDeE6QRvlYoQ5aXR8y4AOIIYcrnNCxcY6GE2PXXT49JvFXeG/wQJvrwtUK53 /zQ2GKj+eZz6vIVnjlzCs6b2gJjK94Mby60g5KTLUDsR1iXVPyXAomxQe+fmJJbTlOntxneVYaKXb 8vNZZiWIFFAzHt23Sa70oNhJSFy66QAYSnpeD5MCA1QbNTCVcM1vNG52S67vInWmZDbdnAWJZ/4EL hyowZ6Wg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xD7Mf-0000000E53O-0M5n; Sat, 03 Oct 2026 21:33:53 +0000 Received: from bali.collaboradmins.com ([2a01:4f8:201:9162::2]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xD7MY-0000000E51M-22x3; Sat, 03 Oct 2026 21:33:52 +0000 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 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261003_143346_685891_ED2AEE7C X-CRM114-Status: GOOD ( 12.00 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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