From: Li.Xiubo@freescale.com (Li Xiubo)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCHv2 1/8] ALSA: Add SAI SoC Digital Audio Interface driver.
Date: Wed, 20 Nov 2013 03:37:45 +0000 [thread overview]
Message-ID: <1DD289F6464F0949A2FCA5AA6DC23F828AE980@039-SN2MPN1-012.039d.mgd.msft.net> (raw)
In-Reply-To: <20131104043338.GA2345@MrMyself>
> The udelay just doesn't make sense to what you are talking about.
>
> Does SAI really need 10us delay between two register-updating?
>
No, this is not must be.
> We basically use udelay only if the IP hardware actually needs it: some
> IP needs time to boot itself up after doing software reset for example.
> But it doesn't look reasonable to me by using udelay to make sure "the
> last enabled".
>
> And from the 'Synchronous mode' you just provided, there're another issue:
>
> + case SNDRV_PCM_TRIGGER_START:
> + case SNDRV_PCM_TRIGGER_RESUME:
> + case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
> + tcsr |= FSL_SAI_CSR_TERE;
> + rcsr |= FSL_SAI_CSR_TERE;
> + writel(rcsr, sai->base + FSL_SAI_RCSR);
> + udelay(10);
> + writel(tcsr, sai->base + FSL_SAI_TCSR);
> + break;
> +
> + case SNDRV_PCM_TRIGGER_STOP:
> + case SNDRV_PCM_TRIGGER_SUSPEND:
> + case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
> + if (!(dai->playback_active || dai->capture_active)) {
> + tcsr &= ~FSL_SAI_CSR_TERE;
> + rcsr &= ~FSL_SAI_CSR_TERE;
> + }
> + writel(rcsr, sai->base + FSL_SAI_RCSR);
> + udelay(10);
> + writel(tcsr, sai->base + FSL_SAI_TCSR);
> + break;
>
> ISSUE 1: You might make sure transmitter is the last enabled.
> However, it's not the first disabled. Is this okay?
>
Yes, this is just programming mistake. I'll revise it.
In this case the transmitter should be the last enabled and the first disabled.
> ISSUE 2: There are two cases listed in 'Synchronous mode'.
> However, your driver doesn't take care of them.
> The SAI's synchronous mode looks like more flexible
> than SSI's. The driver needs to be more sophisticated
> so that it can handle multiple cases when TX/RX clocks
> are controlled by either TX or RX, and surely, the
> asynchronous mode as well.
>
Because in Vybrid the transmitter bit clock and frame sync are to be used by both the transmitter and receiver, and only this case can be used here, so now I only handle this case.
>
> And there's another personal tip: I think you can first try to focus on
> this SAI driver and pend the others. There might be two many things you
> need to refine if you are doing them at the same time.
>
I'll implement them later if needed.
--
Best Regards,
Xiubo
next prev parent reply other threads:[~2013-11-20 3:37 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-01 7:04 No subject Xiubo Li
2013-11-01 7:04 ` [PATCHv2 1/8] ALSA: Add SAI SoC Digital Audio Interface driver Xiubo Li
2013-11-01 8:59 ` Nicolin Chen
2013-11-04 3:45 ` Li Xiubo
2013-11-04 4:33 ` Nicolin Chen
2013-11-20 3:37 ` Li Xiubo [this message]
2013-11-20 3:37 ` Nicolin Chen
2013-11-20 4:16 ` Li Xiubo
2013-11-05 13:26 ` Timur Tabi
2013-11-06 3:27 ` Li Xiubo
2013-11-06 3:31 ` Timur Tabi
2013-11-06 3:53 ` Li Xiubo
2013-11-06 8:12 ` Shawn Guo
2013-11-06 9:38 ` Li Xiubo
2013-11-01 18:25 ` Mark Brown
2013-11-04 7:35 ` Li Xiubo
2013-11-04 16:15 ` Mark Brown
2013-11-05 3:21 ` Li Xiubo
2013-11-06 9:53 ` Mark Brown
2013-11-01 7:04 ` [PATCHv2 2/8] ARM: dts: Add Freescale SAI ALSA SoC Digital Audio Interface node for VF610 Xiubo Li
2013-11-01 7:04 ` [PATCHv2 3/8] ARM: dts: Enables SAI ALSA SoC DAI device for Vybrid VF610 TOWER board Xiubo Li
2013-11-18 18:07 ` Bill Pringlemeir
2013-11-20 3:14 ` Li Xiubo
2013-11-20 16:04 ` Bill Pringlemeir
2013-11-21 2:58 ` Li Xiubo
2013-11-21 14:55 ` Bill Pringlemeir
2013-11-22 6:46 ` Li Xiubo
2013-11-22 15:09 ` Bill Pringlemeir
2013-11-28 7:45 ` Li Xiubo
2013-11-01 7:04 ` [PATCHv2 4/8] Documentation: Add device tree bindings for Freescale SAI Xiubo Li
2013-11-01 7:04 ` [PATCHv2 5/8] ASoC: SGTL5000: Enhance the SGTL5000 codec driver about regulator Xiubo Li
2013-11-01 10:02 ` Nicolin Chen
2013-11-01 18:50 ` Mark Brown
2013-11-06 8:59 ` Li Xiubo
2013-11-06 10:03 ` Mark Brown
2013-11-07 3:01 ` Li Xiubo
2013-11-07 20:38 ` Mark Brown
2013-11-01 7:04 ` [PATCHv2 6/8] ASoC: fsl: add SGTL5000 based audio machine driver Xiubo Li
2013-11-01 10:17 ` Oskar Schirmer
2013-11-05 3:26 ` Li Xiubo
2013-11-01 10:28 ` Nicolin Chen
2013-11-01 12:07 ` Shawn Guo
2013-11-05 6:17 ` Li Xiubo
2013-11-05 3:50 ` Li Xiubo
2013-11-01 18:40 ` Mark Brown
2013-11-04 9:52 ` Li Xiubo
2013-11-20 7:49 ` Li Xiubo
2013-11-01 7:04 ` [PATCHv2 7/8] ARM: dts: Enable SGTL5000 codec based audio driver node for VF610 Xiubo Li
2013-11-01 7:04 ` [PATCHv2 8/8] Documentation: Add device tree bindings for Freescale VF610 sound Xiubo Li
2013-11-01 7:52 ` [PATCHv1 0/8] ALSA: Add SAI driver and enable SGT15000 codec Li Xiubo
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