linux-kernel - Re: [PATCH 5/5] ASoC: rsnd: dma: use extended audio dmac registers when available

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Message-ID: <eb7ac3a6-e386-09e8-54b0-2e0eda90ad66@mentor.com>
Date:   Wed, 13 Mar 2019 15:34:00 +0900
From:   Jiada Wang <jiada_wang@...tor.com>
To:     Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
CC:     <horms@...ge.net.au>, <magnus.damm@...il.com>,
        <robh+dt@...nel.org>, <mark.rutland@....com>,
        <lgirdwood@...il.com>, <broonie@...nel.org>, <perex@...ex.cz>,
        <tiwai@...e.com>, <geert@...ux-m68k.org>,
        <linux-renesas-soc@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <alsa-devel@...a-project.org>
Subject: Re: [PATCH 5/5] ASoC: rsnd: dma: use extended audio dmac registers
 when available

Hi Morimoto-san

thanks for your comments

On 2019/03/13 15:23, Kuninori Morimoto wrote:
> 
> Hi Jiada
> 
>> Some of SoCs have both basic and extended dmac registers set
>> basic set only supports busif0 ~ busif3, in order to use
>> busif4 ~ busif7, extended audio dmac registers need to be used.
>>
>> This patch changes to use extended dmac registers set when it is
>> available in device-tree.
>>
>> Signed-off-by: Jiada Wang <jiada_wang@...tor.com>
>> ---
> 
> 1st of all, if you want to post this kind of patch-set,
> you *should* post driver side patch 1st, and if it was accepted,
> you need to post SoC side patch. Then, you need to indicate
> to SoC maintainer which branch/commit should be based.
> Otherwise, it will 100% breaks git-bisect.
> 
yes, you're right,
sorry about this

> 2nd, in my understanding, our conclusion at Renesas-ML
> is that we don't need to think about basic/extend DMAC register.
> Because extend area is 100% covering basic area.
> In other words, it is compatible.
> Driver side don't need to think about it.
>
I am a little confused,
because latest comment received from simon, suggests to let driver to 
decide which register set to use.

for me, I think it's not necessary, if extended register set is available,
driver shall always use it.

Thanks,
Jiada


>> --- a/sound/soc/sh/rcar/dma.c
>> +++ b/sound/soc/sh/rcar/dma.c
>> @@ -830,7 +830,10 @@ int rsnd_dma_probe(struct rsnd_priv *priv)
>>   	/*
>>   	 * for Gen2 or later
>>   	 */
>> -	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "audmapp");
>> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "extaudmapp");
>> +	if (!res)
>> +		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>> +						   "audmapp");
>>   	dmac = devm_kzalloc(dev, sizeof(*dmac), GFP_KERNEL);
>>   	if (!dmac || !res) {
>>   		dev_err(dev, "dma allocate failed\n");
>> -- 
>> 2.19.2
>>