linux-kernel - Re: [PATCH 03/16] soundwire: cadence: add interface to check clock status

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Message-ID: <20200313120607.GE4885@vkoul-mobl>
Date:   Fri, 13 Mar 2020 17:36:07 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        tiwai@...e.de, broonie@...nel.org, gregkh@...uxfoundation.org,
        jank@...ence.com, srinivas.kandagatla@...aro.org,
        slawomir.blauciak@...el.com,
        Bard liao <yung-chuan.liao@...ux.intel.com>,
        Rander Wang <rander.wang@...ux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Hui Wang <hui.wang@...onical.com>,
        Rander Wang <rander.wang@...el.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>
Subject: Re: [PATCH 03/16] soundwire: cadence: add interface to check clock
 status

On 11-03-20, 13:41, Pierre-Louis Bossart wrote:
> From: Rander Wang <rander.wang@...el.com>
> 
> If master is in clock stop state, driver can't modify registers
> in master except the registers for clock stop setting.
> 
> Signed-off-by: Rander Wang <rander.wang@...el.com>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> ---
>  drivers/soundwire/cadence_master.c | 19 +++++++++++++++++++
>  drivers/soundwire/cadence_master.h |  2 ++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
> index 941809ea00a8..71cba2585151 100644
> --- a/drivers/soundwire/cadence_master.c
> +++ b/drivers/soundwire/cadence_master.c
> @@ -1207,6 +1207,25 @@ static const struct sdw_master_port_ops cdns_port_ops = {
>  	.dpn_port_enable_ch = cdns_port_enable,
>  };
>  
> +/**
> + * sdw_cdns_is_clock_stop: Check clock status
> + *
> + * @cdns: Cadence instance
> + */
> +bool sdw_cdns_is_clock_stop(struct sdw_cdns *cdns)
> +{
> +	u32 status;
> +
> +	status = cdns_readl(cdns, CDNS_MCP_STAT) & CDNS_MCP_STAT_CLK_STOP;
> +	if (status) {
> +		dev_dbg(cdns->dev, "Clock is stopped\n");
> +		return true;
> +	}

This can be further optimized to:

        return !!(cdns_readl(cdns, CDNS_MCP_STAT) & CDNS_MCP_STAT_CLK_STOP);

-- 
~Vinod