From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 23076352030 for ; Sun, 4 Oct 2026 10:52:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791111133; cv=none; b=GqF7njFFW0atx5tluXnWNbTRO4Rrx19Rkn3u8gGcf1cEz0h7pREo8bnuwx9qbImRJmvv3xk05qen7zGcBSj39hF452l5hxyFbO1tfLs7NpFtQAbgXGDvwDy9Vank56UIVsbwsCfqPVox7DWieZPO0jyjYYCcJQvJfloARhWNy8s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791111133; c=relaxed/simple; bh=1KnkVSj/piFydI7sB3zDz2RKRsQmO4Rvj3CNKKnUoiE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JVeu2ma6c5aTCxQbvOP59FzSqfCfYc5JA5ymqWShqBKRT91oQjO8HQjQMXjStabSYqGGZUO86fH/nEcs0ES+1kJqt437kYjCf5LMbSxvuuJ5E7r9NLHc0iwg7HG1Cdxulgm8JUntiotYAE+A8P5C2PaaxjdD+MQwIggmzLgu5M4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FFLg41iw; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FFLg41iw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A0C51F000FF; Sun, 4 Oct 2026 10:52:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791111131; bh=Ded2t/lxa5/OOJ87UbsbJnDc5Xdi5OA3X44Xyk2z2B0=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=FFLg41iwcTX3eTrwV8t5ajXGLkgtY0ZvuL5T/qeDdnKQBwVWD6N5vCzTPBYi+bBZY 05fFRj3tAJZR+cbH5AyVdJa2W40q3K3/wb9BimQtqdglNKNr8+LXBwCiacs6srl2OR D1nb+Bqi7YFJkK8yerA5MXws9WGktv/Pf3ROeJSV0kVYffAZuT0/PNGgMQx5+u214k A7n7yhaCNIk/le8m+R9bbMMpGoc9Bfk21DQzyv2XNzjpVvTYeobV8hfnxfA8c0sh0c 1v8WYrvs0C4AMhH4LDWpQBYsyvPmHVsnuGAofGaPT4Eyd4NqyueuT98NECkdbuH0nJ vVE6AkYtBSPsw== Date: Sun, 4 Oct 2026 12:52:07 +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> <3c0dc77b-b692-498e-aed6-aa97d827b2f4@collabora.com> 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=us-ascii Content-Disposition: inline In-Reply-To: <3c0dc77b-b692-498e-aed6-aa97d827b2f4@collabora.com> On 04-10-26, 00:33, Cristian Ciocaltea wrote: > 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. Ah, looks like AI gave me wrong info about 0 being invalid, this is okay then -- ~Vinod