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SubjectRe: [RFC PATCH 25/40] soundwire: intel: use BIOS information to set clock dividers
On Thu, Jul 25, 2019 at 06:40:17PM -0500, Pierre-Louis Bossart wrote:
> The BIOS provides an Intel-specific property, let's use it to avoid
> hard-coded clock dividers.
>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
> ---
> drivers/soundwire/cadence_master.c | 26 ++++++++++++++++++++++----
> drivers/soundwire/intel.c | 26 ++++++++++++++++++++++++++
> include/linux/soundwire/sdw.h | 2 ++
> 3 files changed, 50 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
> index d84344e29f71..10ebcef2e84e 100644
> --- a/drivers/soundwire/cadence_master.c
> +++ b/drivers/soundwire/cadence_master.c
> @@ -173,8 +173,6 @@
> #define CDNS_PDI_CONFIG_PORT GENMASK(4, 0)
>
> /* Driver defaults */
> -
> -#define CDNS_DEFAULT_CLK_DIVIDER 0
> #define CDNS_DEFAULT_SSP_INTERVAL 0x18
> #define CDNS_TX_TIMEOUT 2000
>
> @@ -973,7 +971,10 @@ static u32 cdns_set_default_frame_shape(int n_rows, int n_cols)
> */
> int sdw_cdns_init(struct sdw_cdns *cdns)
> {
> + struct sdw_bus *bus = &cdns->bus;
> + struct sdw_master_prop *prop = &bus->prop;
> u32 val;
> + int divider;
> int ret;
>
> /* Exit clock stop */
> @@ -985,9 +986,17 @@ int sdw_cdns_init(struct sdw_cdns *cdns)
> }
>
> /* Set clock divider */
> + divider = (prop->mclk_freq / prop->max_clk_freq) - 1;

Do you expect mclk_freq and max_clk_freq to be same?

> val = cdns_readl(cdns, CDNS_MCP_CLK_CTRL0);
> - val |= CDNS_DEFAULT_CLK_DIVIDER;
> + val |= divider;
> cdns_writel(cdns, CDNS_MCP_CLK_CTRL0, val);
> + cdns_writel(cdns, CDNS_MCP_CLK_CTRL1, val);
> +
> + pr_err("plb: mclk %d max_freq %d divider %d register %x\n",
> + prop->mclk_freq,
> + prop->max_clk_freq,
> + divider,
> + val);

This can be removed.

>
> /* Set the default frame shape */
> val = cdns_set_default_frame_shape(prop->default_row,
> @@ -1035,6 +1044,7 @@ EXPORT_SYMBOL(sdw_cdns_init);
>
> int cdns_bus_conf(struct sdw_bus *bus, struct sdw_bus_params *params)
> {
> + struct sdw_master_prop *prop = &bus->prop;
> struct sdw_cdns *cdns = bus_to_cdns(bus);
> int mcp_clkctrl_off, mcp_clkctrl;
> int divider;
> @@ -1044,7 +1054,9 @@ int cdns_bus_conf(struct sdw_bus *bus, struct sdw_bus_params *params)
> return -EINVAL;
> }
>
> - divider = (params->max_dr_freq / params->curr_dr_freq) - 1;
> + divider = prop->mclk_freq * SDW_DOUBLE_RATE_FACTOR /

What is the reason for not using max_dr_freq? Its precomputed as
prop->max_clk_freq * SDW_DOUBLE_RATE_FACTOR;

> + params->curr_dr_freq;
> + divider--; /* divider is 1/(N+1) */
>
> if (params->next_bank)
> mcp_clkctrl_off = CDNS_MCP_CLK_CTRL1;
> @@ -1055,6 +1067,12 @@ int cdns_bus_conf(struct sdw_bus *bus, struct sdw_bus_params *params)
> mcp_clkctrl |= divider;
> cdns_writel(cdns, mcp_clkctrl_off, mcp_clkctrl);
>
> + pr_err("plb: mclk * 2 %d curr_dr_freq %d divider %d register %x\n",
> + prop->mclk_freq * SDW_DOUBLE_RATE_FACTOR,
> + params->curr_dr_freq,
> + divider,
> + mcp_clkctrl);
> +
> return 0;
> }
> EXPORT_SYMBOL(cdns_bus_conf);
> diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
> index c718c9c67a37..796ac2bc8cea 100644
> --- a/drivers/soundwire/intel.c
> +++ b/drivers/soundwire/intel.c
> @@ -917,11 +917,37 @@ static int intel_register_dai(struct sdw_intel *sdw)
> dais, num_dai);
> }
>
> +static int sdw_master_read_intel_prop(struct sdw_bus *bus)
> +{
> + struct sdw_master_prop *prop = &bus->prop;
> + struct fwnode_handle *link;
> + char name[32];
> + int nval, i;
> +
> + /* Find master handle */
> + snprintf(name, sizeof(name),
> + "mipi-sdw-link-%d-subproperties", bus->link_id);
> +
> + link = device_get_named_child_node(bus->dev, name);
> + if (!link) {
> + dev_err(bus->dev, "Master node %s not found\n", name);
> + return -EIO;
> + }
> +
> + fwnode_property_read_u32(link,
> + "intel-sdw-ip-clock",
> + &prop->mclk_freq);
> + return 0;
> +}
> +
> static int intel_prop_read(struct sdw_bus *bus)
> {
> /* Initialize with default handler to read all DisCo properties */
> sdw_master_read_prop(bus);
>
> + /* read Intel-specific properties */
> + sdw_master_read_intel_prop(bus);
> +
> return 0;
> }
>
> diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
> index 31d1e8acf25b..b6acc436ac80 100644
> --- a/include/linux/soundwire/sdw.h
> +++ b/include/linux/soundwire/sdw.h
> @@ -379,6 +379,7 @@ struct sdw_slave_prop {
> * @dynamic_frame: Dynamic frame shape supported
> * @err_threshold: Number of times that software may retry sending a single
> * command
> + * @mclk_freq: clock reference passed to SoundWire Master, in Hz.
> */
> struct sdw_master_prop {
> u32 revision;
> @@ -393,6 +394,7 @@ struct sdw_master_prop {
> u32 default_col;
> bool dynamic_frame;
> u32 err_threshold;
> + u32 mclk_freq;
> };
>
> int sdw_master_read_prop(struct sdw_bus *bus);
> --
> 2.20.1
>

--

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