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    SubjectRe: [alsa-devel] [RFC PATCH 26/40] soundwire: cadence_master: fix divider setting in clock register
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    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@linux.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@linux.intel.com>
    >> Signed-off-by: Pierre-Louis Bossart
    >> <pierre-louis.bossart@linux.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,

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