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 3D7D6CA5FE4 for ; Sat, 3 Oct 2026 20:39:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=KtQBzVs/5zH2wzz3DTTqz4sbFVRyoTRJfH8knqfr5ok=; b=ItAslT0CfDcS9O OciQGgbDHGZ+H4r5m6nEFFKGnlPCsoVlHpjav2tCghE6uszbOT6hKbulRcAwePXcaxkCiniP1ZXj/ cF+603cANY05GYh8jyMO1KiuPyk7UeJlAvll1k7eBPWnXldr7oDugfKrlHQxg7z8eoKjdtekE9cQi upPm5DIdXxVelLUhVDsPhLxA3DqVXrskQC8sFPjipzPJgtaIdZT2FRNgBcs48X6i5UGnW0NDruU8D bVes5MD45QHBE2zopdLZq4Y4GKZgz7K+v28tPIw+/KBzHvKykmw2j76kpyK5uOS4I2EPcmSVjrtRp 1Ao9kUAFCMuP5CrfamcA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xD6WC-0000000E1Cb-0Vnh; Sat, 03 Oct 2026 20:39:40 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xD6WB-0000000E1CG-04pY; Sat, 03 Oct 2026 20:39:39 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id E6F2560120; Sat, 3 Oct 2026 20:39:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5A7D1F0089B; Sat, 3 Oct 2026 20:39:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791059977; bh=tSUhjkfC0Q2//h6dWhCqwgi4jeXYnkhNBRpnLdYChkc=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=noA68/7ksmbSP7UWWC0+zA5kZh994tu+Z+faRzxxNrfp0AT6nCJlGUpSNMXxx1fUP GRIbAYUlUrqClUoxTLdcx0TP8SVcfUtkH+sAaETa9Z8whx8gxSbLAjebarfJitsFJF 7XHDuUURtnQGPfZYoHN2F8p+EXF5ACwpGpguq31uHjm3yolN7WBeTPNBs3Z2NS5TNV DwJksVsvtfbsS5ObA9cWGmuGLG1RKCry+TCfkDNBR7d57lxhkrKnD6yM4B8R33rsD1 yN2OmBM2kE9RRGwbcMgGOMQzjVKgx3pCmUzyUuVqfypnWNqg8MMkoAz6dR3ba7HeVD zxLHpuf9ort0A== Date: Sat, 3 Oct 2026 22:39:34 +0200 From: Vinod Koul To: Cristian Ciocaltea 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 Subject: Re: [PATCH v2 1/3] phy: hdmi: Add optional FRL TxFFE config options Message-ID: References: <20260901-hdptx-ffe-v2-0-3a5922c76fc5@collabora.com> <20260901-hdptx-ffe-v2-1-3a5922c76fc5@collabora.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20260901-hdptx-ffe-v2-1-3a5922c76fc5@collabora.com> X-BeenThere: linux-rockchip@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Upstream kernel work for Rockchip platforms List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+linux-rockchip=archiver.kernel.org@lists.infradead.org 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..? > > The flag-based approach reflects an important invariant in the link > training process: whenever the FRL rate or lane count changes, the TxFFE > level must be reset to zero. A separate phy_configure() call with > set_ffe_level can only follow after the rate has been established, > making the two operations deliberately distinct. > > Signed-off-by: Cristian Ciocaltea > --- > include/linux/phy/phy-hdmi.h | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/include/linux/phy/phy-hdmi.h b/include/linux/phy/phy-hdmi.h > index d4cf4430ee8f..1d4b62475079 100644 > --- a/include/linux/phy/phy-hdmi.h > +++ b/include/linux/phy/phy-hdmi.h > @@ -19,6 +19,10 @@ enum phy_hdmi_mode { > * @tmds_char_rate: HDMI TMDS Character Rate in Hertz. > * @frl.rate_per_lane: HDMI FRL Rate per Lane in Gbps. > * @frl.lanes: HDMI FRL lanes count. > + * @frl.ffe_level: Transmitter Feed Forward Equalizer Level. > + * Optional, only meaningful when set_ffe_level flag is on. > + * @frl.set_ffe_level: Flag indicating whether or not to reconfigure ffe_level. > + * All the other struct fields must be ignored when this is used. > * > * This structure is used to represent the configuration state of a HDMI phy. > */ > @@ -29,6 +33,8 @@ struct phy_configure_opts_hdmi { > struct { > u8 rate_per_lane; > u8 lanes; > + u8 ffe_level; > + u8 set_ffe_level : 1; > } frl; > }; > }; > > -- > 2.55.0 -- ~Vinod _______________________________________________ Linux-rockchip mailing list Linux-rockchip@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-rockchip 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 EDBFECA5FDD for ; Sat, 3 Oct 2026 20:39:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; 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Sat, 3 Oct 2026 20:39:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791059977; bh=tSUhjkfC0Q2//h6dWhCqwgi4jeXYnkhNBRpnLdYChkc=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=noA68/7ksmbSP7UWWC0+zA5kZh994tu+Z+faRzxxNrfp0AT6nCJlGUpSNMXxx1fUP GRIbAYUlUrqClUoxTLdcx0TP8SVcfUtkH+sAaETa9Z8whx8gxSbLAjebarfJitsFJF 7XHDuUURtnQGPfZYoHN2F8p+EXF5ACwpGpguq31uHjm3yolN7WBeTPNBs3Z2NS5TNV DwJksVsvtfbsS5ObA9cWGmuGLG1RKCry+TCfkDNBR7d57lxhkrKnD6yM4B8R33rsD1 yN2OmBM2kE9RRGwbcMgGOMQzjVKgx3pCmUzyUuVqfypnWNqg8MMkoAz6dR3ba7HeVD zxLHpuf9ort0A== Date: Sat, 3 Oct 2026 22:39:34 +0200 From: Vinod Koul To: Cristian Ciocaltea 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 Subject: Re: [PATCH v2 1/3] phy: hdmi: Add optional FRL TxFFE config options Message-ID: References: <20260901-hdptx-ffe-v2-0-3a5922c76fc5@collabora.com> <20260901-hdptx-ffe-v2-1-3a5922c76fc5@collabora.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20260901-hdptx-ffe-v2-1-3a5922c76fc5@collabora.com> X-BeenThere: linux-phy@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux Phy Mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-phy" Errors-To: linux-phy-bounces+linux-phy=archiver.kernel.org@lists.infradead.org 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..? > > The flag-based approach reflects an important invariant in the link > training process: whenever the FRL rate or lane count changes, the TxFFE > level must be reset to zero. A separate phy_configure() call with > set_ffe_level can only follow after the rate has been established, > making the two operations deliberately distinct. > > Signed-off-by: Cristian Ciocaltea > --- > include/linux/phy/phy-hdmi.h | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/include/linux/phy/phy-hdmi.h b/include/linux/phy/phy-hdmi.h > index d4cf4430ee8f..1d4b62475079 100644 > --- a/include/linux/phy/phy-hdmi.h > +++ b/include/linux/phy/phy-hdmi.h > @@ -19,6 +19,10 @@ enum phy_hdmi_mode { > * @tmds_char_rate: HDMI TMDS Character Rate in Hertz. > * @frl.rate_per_lane: HDMI FRL Rate per Lane in Gbps. > * @frl.lanes: HDMI FRL lanes count. > + * @frl.ffe_level: Transmitter Feed Forward Equalizer Level. > + * Optional, only meaningful when set_ffe_level flag is on. > + * @frl.set_ffe_level: Flag indicating whether or not to reconfigure ffe_level. > + * All the other struct fields must be ignored when this is used. > * > * This structure is used to represent the configuration state of a HDMI phy. > */ > @@ -29,6 +33,8 @@ struct phy_configure_opts_hdmi { > struct { > u8 rate_per_lane; > u8 lanes; > + u8 ffe_level; > + u8 set_ffe_level : 1; > } frl; > }; > }; > > -- > 2.55.0 -- ~Vinod -- linux-phy mailing list linux-phy@lists.infradead.org https://lists.infradead.org/mailman/listinfo/linux-phy 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 3F938CA5FDD for ; Sat, 3 Oct 2026 20:39:49 +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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tSUhjkfC0Q2//h6dWhCqwgi4jeXYnkhNBRpnLdYChkc=; b=VqEHk/L7iQ9QOwa7E/eqZuKjbA GvLJOlH9zlCzKVJbemfudf8fjV45IRrvai7tKWFbXOUT5fM8cjK1l4oBbwJALb6VKfpHAM1+QS11I Pm8RyzqphBOO54CWcTnBQI4y8w/gLmavPVkXfFFdJWcFCNUaNaIoogbF8c0Ov8RCsquwgzmrJPtF/ INKMjORVLatOZXs9HAiDg5n3gRSwTVqIhMBcJV/w+5BIXCZPS1OXesnVEt7pUN0KhhvIWMTwmmsUA U89tTQUYxBjRzW7Z1+8zYOjrTnzII5LzYmpRH4dBId2n74h3iF7InVYvBfzgSzkWIM4VZQeUdtJJn QQoRL9DA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xD6WB-0000000E1CT-48kK; Sat, 03 Oct 2026 20:39:39 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xD6WB-0000000E1CG-04pY; Sat, 03 Oct 2026 20:39:39 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id E6F2560120; Sat, 3 Oct 2026 20:39:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5A7D1F0089B; Sat, 3 Oct 2026 20:39:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791059977; bh=tSUhjkfC0Q2//h6dWhCqwgi4jeXYnkhNBRpnLdYChkc=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=noA68/7ksmbSP7UWWC0+zA5kZh994tu+Z+faRzxxNrfp0AT6nCJlGUpSNMXxx1fUP GRIbAYUlUrqClUoxTLdcx0TP8SVcfUtkH+sAaETa9Z8whx8gxSbLAjebarfJitsFJF 7XHDuUURtnQGPfZYoHN2F8p+EXF5ACwpGpguq31uHjm3yolN7WBeTPNBs3Z2NS5TNV DwJksVsvtfbsS5ObA9cWGmuGLG1RKCry+TCfkDNBR7d57lxhkrKnD6yM4B8R33rsD1 yN2OmBM2kE9RRGwbcMgGOMQzjVKgx3pCmUzyUuVqfypnWNqg8MMkoAz6dR3ba7HeVD zxLHpuf9ort0A== Date: Sat, 3 Oct 2026 22:39:34 +0200 From: Vinod Koul To: Cristian Ciocaltea 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 Subject: Re: [PATCH v2 1/3] phy: hdmi: Add optional FRL TxFFE config options Message-ID: References: <20260901-hdptx-ffe-v2-0-3a5922c76fc5@collabora.com> <20260901-hdptx-ffe-v2-1-3a5922c76fc5@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260901-hdptx-ffe-v2-1-3a5922c76fc5@collabora.com> 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 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..? > > The flag-based approach reflects an important invariant in the link > training process: whenever the FRL rate or lane count changes, the TxFFE > level must be reset to zero. A separate phy_configure() call with > set_ffe_level can only follow after the rate has been established, > making the two operations deliberately distinct. > > Signed-off-by: Cristian Ciocaltea > --- > include/linux/phy/phy-hdmi.h | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/include/linux/phy/phy-hdmi.h b/include/linux/phy/phy-hdmi.h > index d4cf4430ee8f..1d4b62475079 100644 > --- a/include/linux/phy/phy-hdmi.h > +++ b/include/linux/phy/phy-hdmi.h > @@ -19,6 +19,10 @@ enum phy_hdmi_mode { > * @tmds_char_rate: HDMI TMDS Character Rate in Hertz. > * @frl.rate_per_lane: HDMI FRL Rate per Lane in Gbps. > * @frl.lanes: HDMI FRL lanes count. > + * @frl.ffe_level: Transmitter Feed Forward Equalizer Level. > + * Optional, only meaningful when set_ffe_level flag is on. > + * @frl.set_ffe_level: Flag indicating whether or not to reconfigure ffe_level. > + * All the other struct fields must be ignored when this is used. > * > * This structure is used to represent the configuration state of a HDMI phy. > */ > @@ -29,6 +33,8 @@ struct phy_configure_opts_hdmi { > struct { > u8 rate_per_lane; > u8 lanes; > + u8 ffe_level; > + u8 set_ffe_level : 1; > } frl; > }; > }; > > -- > 2.55.0 -- ~Vinod