From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from na01-by2-obe.outbound.protection.outlook.com (mail-by2on0128.outbound.protection.outlook.com [207.46.100.128]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 1027C1A0C2A for ; Thu, 22 Jan 2015 17:19:14 +1100 (AEDT) Date: Thu, 22 Jan 2015 14:20:06 +0800 From: Zidan Wang To: Nicolin Chen Subject: Re: [alsa-devel][PATCH 2/3] ASoC: fsl_sai: Add support for tdm slots operation Message-ID: <20150122062004.GA7046@b50113> References: <1421756480-7055-1-git-send-email-zidan.wang@freescale.com> <1421756480-7055-3-git-send-email-zidan.wang@freescale.com> <20150121180801.GA3361@Alpha> <20150122045515.GA3467@b50113> <20150122054409.GA7748@Asurada> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" In-Reply-To: <20150122054409.GA7748@Asurada> Cc: alsa-devel@alsa-project.org, timur@tabi.org, Zidan Wang , Xiubo.Lee@gmail.com, tiwai@suse.de, linux-kernel@vger.kernel.org, lgirdwood@gmail.com, perex@perex.cz, broonie@kernel.org, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, Jan 21, 2015 at 09:44:10PM -0800, Nicolin Chen wrote: > On Thu, Jan 22, 2015 at 12:55:35PM +0800, Zidan Wang wrote: > > On Wed, Jan 21, 2015 at 10:08:03AM -0800, Nicolin Chen wrote: > > > On Tue, Jan 20, 2015 at 08:21:19PM +0800, Zidan Wang wrote: > > > > @@ -369,10 +380,25 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream, > > > > u32 word_width = snd_pcm_format_width(params_format(params)); > > > > u32 val_cr4 = 0, val_cr5 = 0; > > > > int ret; > > > > + u32 bclk; > > > > + > > > > + if (channels == 1) > > > > + channels = 2; > > > > + > > > > + if (!sai->slots || sai->slots % channels) > > > > + sai->slots = channels; > > > > + > > > > + sai->slots = sai->slots / channels; > > > > + > > > > + if (sai->slot_width < word_width || sai->is_dsp_mode) > > > > + sai->slot_width = word_width; > > > > > > Could you pls explain a bit what's this overriding for? > > > Or it might be better to put into a comment. > > > > > In machine driver, we should use snd_soc_dai_set_tdm_slot to set slots > > and slot width. In my opinion, slots in machine driver means the slot > > number of all channels. But in sai driver, the slots means the slot number > > of one channel. So snd_soc_calc_bclk use fs*sample_size*channels*tdm_slots > > to caculate bclk. > > Could you pls use the standard way as you described for slot number > in machine driver instead of defining some other meanings? That one > is really confusing, not to mention a code without any comment. > > You can add some extra local variables with extinguished names and > calculate the slot number and channels you want without changing > the original sai->slots and channels in the hw_params(). As you said, > you only need that new slot number and channels for snd_soc_calc_bclk > call. So you may also put this code right before the call -- a normal > routine doesn't need to recalculate the special slots and channels, > right? > > Nicolin Actually i don't kown which meaning is the standard way. Because i found in wm8993 and wm8904 codec driver, they also use slots/channels to set tdm_slots in set_tdm_slot function. Best Regards, Zidan