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SubjectRe: [alsa-devel] [RFC PATCH 16/40] soundwire: cadence_master: improve startup sequence with link hw_reset
On Thu, Jul 25, 2019 at 06:40:08PM -0500, Pierre-Louis Bossart wrote:
> Enable interrupts first, then engage hardware bus reset with maximum
> duration to make sure the Slave(s) correctly detect the reset pattern
> and to ensure electrical conflicts can be resolved.
>
> Without these changes the initialization is randomly corrupted by bus
> clashes, parity errors and Slave attachment does not generate any
> interrupt, despite the status showing them being attached.
>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
> ---
> drivers/soundwire/cadence_master.c | 35 +++++++++++++++++++++++++-----
> 1 file changed, 30 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
> index 25d5c7267c15..442f78c00f09 100644
> --- a/drivers/soundwire/cadence_master.c
> +++ b/drivers/soundwire/cadence_master.c
> @@ -778,6 +778,31 @@ EXPORT_SYMBOL(sdw_cdns_thread);
> * init routines
> */
>
> +static int do_reset(struct sdw_cdns *cdns)
> +{
> + int ret;
> +
> + /* program maximum length reset to be safe */
> + cdns_updatel(cdns, CDNS_MCP_CONTROL,
> + CDNS_MCP_CONTROL_RST_DELAY,
> + CDNS_MCP_CONTROL_RST_DELAY);
> +
> + /* use hardware generated reset */
> + cdns_updatel(cdns, CDNS_MCP_CONTROL,
> + CDNS_MCP_CONTROL_HW_RST,
> + CDNS_MCP_CONTROL_HW_RST);
> +
> + /* enable bus operations with clock and data */
> + cdns_updatel(cdns, CDNS_MCP_CONFIG,
> + CDNS_MCP_CONFIG_OP,
> + CDNS_MCP_CONFIG_OP_NORMAL);
> +
> + /* commit changes */
> + ret = cdns_update_config(cdns);
> +
> + return ret;

+ return cdns_update_config(cdns);

and remove the "ret" variable.

Thanks
Guennadi

> +}
> +
> /**
> * sdw_cdns_enable_interrupt() - Enable SDW interrupts and update config
> * @cdns: Cadence instance
> @@ -809,7 +834,7 @@ int sdw_cdns_enable_interrupt(struct sdw_cdns *cdns)
>
> cdns_writel(cdns, CDNS_MCP_INTMASK, mask);
>
> - return 0;
> + return do_reset(cdns);
> }
> EXPORT_SYMBOL(sdw_cdns_enable_interrupt);
>
> @@ -958,6 +983,10 @@ int sdw_cdns_init(struct sdw_cdns *cdns)
> cdns_writel(cdns, CDNS_MCP_SSP_CTRL0, CDNS_DEFAULT_SSP_INTERVAL);
> cdns_writel(cdns, CDNS_MCP_SSP_CTRL1, CDNS_DEFAULT_SSP_INTERVAL);
>
> + /* flush command FIFOs */
> + cdns_updatel(cdns, CDNS_MCP_CONTROL, CDNS_MCP_CONTROL_CMD_RST,
> + CDNS_MCP_CONTROL_CMD_RST);
> +
> /* Set cmd accept mode */
> cdns_updatel(cdns, CDNS_MCP_CONTROL, CDNS_MCP_CONTROL_CMD_ACCEPT,
> CDNS_MCP_CONTROL_CMD_ACCEPT);
> @@ -980,10 +1009,6 @@ int sdw_cdns_init(struct sdw_cdns *cdns)
> /* Set cmd mode for Tx and Rx cmds */
> val &= ~CDNS_MCP_CONFIG_CMD;
>
> - /* Set operation to normal */
> - val &= ~CDNS_MCP_CONFIG_OP;
> - val |= CDNS_MCP_CONFIG_OP_NORMAL;
> -
> cdns_writel(cdns, CDNS_MCP_CONFIG, val);
>
> /* commit changes */
> --
> 2.20.1
>
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel@alsa-project.org
> https://mailman.alsa-project.org/mailman/listinfo/alsa-devel

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