linux-kernel - Re: [RFC PATCH 26/40] soundwire: cadence_master: fix divider setting in clock register

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Date:   Mon, 5 Aug 2019 16:10:47 +0530
From:   Sanyog Kale <sanyog.r.kale@...el.com>
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, vkoul@...nel.org,
        gregkh@...uxfoundation.org, jank@...ence.com,
        srinivas.kandagatla@...aro.org, slawomir.blauciak@...el.com,
        Rander Wang <rander.wang@...ux.intel.com>
Subject: Re: [RFC PATCH 26/40] soundwire: cadence_master: fix divider setting
 in clock register

On Thu, Jul 25, 2019 at 06:40:18PM -0500, Pierre-Louis Bossart wrote:
> From: Rander Wang <rander.wang@...ux.intel.com>
> 
> The existing code uses an OR operation which would mix the original
> divider setting with the new one, resulting in an invalid
> configuration that can make codecs hang.
> 
> Add the mask definition and use cdns_updatel to update divider
> 
> Signed-off-by: Rander Wang <rander.wang@...ux.intel.com>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> ---
>  drivers/soundwire/cadence_master.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
> index 10ebcef2e84e..18c6ac026e85 100644
> --- a/drivers/soundwire/cadence_master.c
> +++ b/drivers/soundwire/cadence_master.c
> @@ -57,6 +57,7 @@
>  #define CDNS_MCP_SSP_CTRL1			0x28
>  #define CDNS_MCP_CLK_CTRL0			0x30
>  #define CDNS_MCP_CLK_CTRL1			0x38
> +#define CDNS_MCP_CLK_MCLKD_MASK		GENMASK(7, 0)
>  
>  #define CDNS_MCP_STAT				0x40
>  
> @@ -988,9 +989,11 @@ int sdw_cdns_init(struct sdw_cdns *cdns)
>  	/* Set clock divider */
>  	divider	= (prop->mclk_freq / prop->max_clk_freq) - 1;
>  	val = cdns_readl(cdns, CDNS_MCP_CLK_CTRL0);

reg read of CLK_CTRL0 can be removed.

> -	val |= divider;
> -	cdns_writel(cdns, CDNS_MCP_CLK_CTRL0, val);
> -	cdns_writel(cdns, CDNS_MCP_CLK_CTRL1, val);
> +
> +	cdns_updatel(cdns, CDNS_MCP_CLK_CTRL0,
> +		     CDNS_MCP_CLK_MCLKD_MASK, divider);
> +	cdns_updatel(cdns, CDNS_MCP_CLK_CTRL1,
> +		     CDNS_MCP_CLK_MCLKD_MASK, divider);
>  
>  	pr_err("plb: mclk %d max_freq %d divider %d register %x\n",
>  	       prop->mclk_freq,
> @@ -1064,8 +1067,7 @@ int cdns_bus_conf(struct sdw_bus *bus, struct sdw_bus_params *params)
>  		mcp_clkctrl_off = CDNS_MCP_CLK_CTRL0;
>  
>  	mcp_clkctrl = cdns_readl(cdns, mcp_clkctrl_off);

same as above.

> -	mcp_clkctrl |= divider;
> -	cdns_writel(cdns, mcp_clkctrl_off, mcp_clkctrl);
> +	cdns_updatel(cdns, mcp_clkctrl_off, CDNS_MCP_CLK_MCLKD_MASK, divider);
>  
>  	pr_err("plb: mclk * 2 %d curr_dr_freq %d divider %d register %x\n",
>  	       prop->mclk_freq * SDW_DOUBLE_RATE_FACTOR,
> -- 
> 2.20.1
> 

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