linux-kernel - Re: [PATCH v1 2/3] ASoC: rsnd: Allow reconfiguration of clock rate

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Date:   23 Jul 2019 10:40:53 +0900
From:   Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
To:     Jiada Wang <jiada_wang@...tor.com>
Cc:     <lgirdwood@...il.com>, <broonie@...nel.org>, <perex@...ex.cz>,
        <tiwai@...e.com>, <twischer@...adit-jv.com>,
        <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 2/3] ASoC: rsnd: Allow reconfiguration of clock rate


Hi Jiada, again

> The solution looks very over-kill to me,
> especiallyq [3/3] patch is too much to me.
> 
> 1st, can we start clock at .hw_param, instead of .prepare ?
> and stop it at .hw_free ?
> 
> 2nd, can we keep usrcnt setup as-is ?
> I guess we can just avoid rsnd_ssi_master_clk_start() if ssi->rate was not 0 ?
> similar for rsnd_ssi_master_clk_stop()

In my quick check, I used your [1/3] patch and below.
It works for me, but I don't know detail of your test case.

----------
diff --git a/sound/soc/sh/rcar/ssi.c b/sound/soc/sh/rcar/ssi.c
index f6a7466..f26ffd1 100644
--- a/sound/soc/sh/rcar/ssi.c
+++ b/sound/soc/sh/rcar/ssi.c
@@ -286,19 +286,8 @@ static int rsnd_ssi_master_clk_start(struct rsnd_mod *mod,
 	if (rsnd_ssi_is_multi_slave(mod, io))
 		return 0;
 
-	if (ssi->usrcnt > 0) {
-		if (ssi->rate != rate) {
-			dev_err(dev, "SSI parent/child should use same rate\n");
-			return -EINVAL;
-		}
-
-		if (ssi->chan != chan) {
-			dev_err(dev, "SSI parent/child should use same chan\n");
-			return -EINVAL;
-		}
-
+	if (ssi->rate)
 		return 0;
-	}
 
 	if (rsnd_runtime_is_tdm_split(io))
 		chan = rsnd_io_converted_chan(io);
@@ -349,7 +338,7 @@ static void rsnd_ssi_master_clk_stop(struct rsnd_mod *mod,
 	if (!rsnd_ssi_can_output_clk(mod))
 		return;
 
-	if (ssi->usrcnt > 1)
+	if (!ssi->rate)
 		return;
 
 	ssi->cr_clk	= 0;
@@ -539,6 +528,17 @@ static int rsnd_ssi_hw_params(struct rsnd_mod *mod,
 	return 0;
 }
 
+static int rsnd_ssi_hw_free(struct rsnd_mod *mod, struct rsnd_dai_stream *io,
+			    struct snd_pcm_substream *substream)
+{
+	if (!rsnd_ssi_is_run_mods(mod, io))
+		return 0;
+
+	rsnd_ssi_master_clk_stop(mod, io);
+
+	return 0;
+}
+
 static int rsnd_ssi_start(struct rsnd_mod *mod,
 			  struct rsnd_dai_stream *io,
 			  struct rsnd_priv *priv)
@@ -925,6 +925,7 @@ static struct rsnd_mod_ops rsnd_ssi_pio_ops = {
 	.pointer	= rsnd_ssi_pio_pointer,
 	.pcm_new	= rsnd_ssi_pcm_new,
 	.hw_params	= rsnd_ssi_hw_params,
+	.hw_free	= rsnd_ssi_hw_free,
 	.prepare	= rsnd_ssi_prepare,
 	.get_status	= rsnd_ssi_get_status,
 };
@@ -1012,6 +1013,7 @@ static struct rsnd_mod_ops rsnd_ssi_dma_ops = {
 	.pcm_new	= rsnd_ssi_pcm_new,
 	.fallback	= rsnd_ssi_fallback,
 	.hw_params	= rsnd_ssi_hw_params,
+	.hw_free	= rsnd_ssi_hw_free,
 	.prepare	= rsnd_ssi_prepare,
 	.get_status	= rsnd_ssi_get_status,
 };
----------