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

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Message-ID: <552565d2-1734-3c24-3a78-379d08e35110@linux.intel.com>
Date:   Fri, 26 Jul 2019 13:56:45 +0800
From:   "rander.wang" <rander.wang@...ux.intel.com>
To:     Bard liao <yung-chuan.liao@...ux.intel.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        alsa-devel@...a-project.org
Cc:     tiwai@...e.de, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, vkoul@...nel.org, broonie@...nel.org,
        srinivas.kandagatla@...aro.org, jank@...ence.com,
        slawomir.blauciak@...el.com, Sanyog Kale <sanyog.r.kale@...el.com>
Subject: Re: [alsa-devel] [RFC PATCH 26/40] soundwire: cadence_master: fix
 divider setting in clock register


在 7/26/2019 1:19 PM, Bard liao 写道:
>
> On 7/26/2019 7:40 AM, 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);
>
>
> Do we still need to read cdns_readl(cdns, CDNS_MCP_CLK_CTRL0)
>
> after this change?
>
The val is used to print debug message,  and my opinion is to change the log

from pr_err("plb: ........") to dev_dbg(bus->dev, "........") to follow 
the dev_dbg

usage in this file.

>
>> -    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 here.
>
Also refine the debug log.
>
>> -    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,