Re: [PATCH 1/8] ASoC: tegra: Add a TDM configuration callback

From: Mark Brown <broonie@kernel.org>
To: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Cc: linux-kernel@lists.codethink.co.uk, alsa-devel@alsa-project.org,
	Takashi Iwai <tiwai@suse.com>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Ben Dooks <ben.dooks@codethink.co.uk>,
	Thierry Reding <thierry.reding@gmail.com>,
	Edward Cragg <edward.cragg@codethink.co.uk>,
	linux-tegra@vger.kernel.org, Jon Hunter <jonathanh@nvidia.com>,
	linux-tegra-owner@vger.kernel.org
Subject: Re: [PATCH 1/8] ASoC: tegra: Add a TDM configuration callback
Date: Wed, 18 Sep 2019 16:02:48 +0100	[thread overview]
Message-ID: <20190918150248.GM2596@sirena.co.uk> (raw)
In-Reply-To: <40d78f13-c1b9-3e2d-c144-2209a4c0d716@linux.intel.com>

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On Wed, Sep 18, 2019 at 08:33:50AM -0500, Pierre-Louis Bossart wrote:
> On 9/18/19 5:48 AM, Mark Brown wrote:

> > In DSP modes only one edge really matters anyway so it's not super
> > important how long the pulse is.

> There are exceptions to the rule.
> In the early days of SOF, we had to provide support for amplifiers that did
> require a pulse larger than a bit. In the SOF IPC we added an
> 'frame_pulse_width' field to pass the configuration all the way from
> topology to the firmware and Intel SSP driver.
> The other quirk we added is the ability to control zero-padding per slot
> instead of at the end of the frame, e.g. 1 bit of padding after 24 bits when
> using 4 slots w/ 25 bits in a 100-bit frame.

Neither of those is part of the core DSP mode definition though in the
same way that constraints like MCLK or BCLK ratios aren't.  They're
modifiers on top.

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