[PATCH] soundwire: stream: Fix test for DP prepare complete

[Pierre-Louis Bossart]

On 6/18/21 9:47 AM, Richard Fitzgerald wrote:
> In sdw_prep_deprep_slave_ports(), after the wait_for_completion()
> the DP prepare status register is read. If this indicates that the
> port is now prepared, the code should continue with the port setup.
> It is irrelevant whether the wait_for_completion() timed out if the
> port is now ready.
> 
> The previous implementation would always fail if the
> wait_for_completion() timed out, even if the port was reporting
> successful prepare.
> 
> This patch also fixes a minor bug where the return from sdw_read()
> was not checked for error - any error code with LSBits clear could
> be misinterpreted as a successful port prepare.
> 
> Fixes: 79df15b7d37c ("soundwire: Add helpers for ports operations")
> Signed-off-by: Richard Fitzgerald <rf at opensource.cirrus.com>

Looks good to me

Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>

> ---
>  drivers/soundwire/stream.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
> index 1eaedaaba094..1a18308f4ef4 100644
> --- a/drivers/soundwire/stream.c
> +++ b/drivers/soundwire/stream.c
> @@ -422,7 +422,6 @@ static int sdw_prep_deprep_slave_ports(struct sdw_bus *bus,
>  	struct completion *port_ready;
>  	struct sdw_dpn_prop *dpn_prop;
>  	struct sdw_prepare_ch prep_ch;
> -	unsigned int time_left;
>  	bool intr = false;
>  	int ret = 0, val;
>  	u32 addr;
> @@ -479,15 +478,15 @@ static int sdw_prep_deprep_slave_ports(struct sdw_bus *bus,
>  
>  		/* Wait for completion on port ready */
>  		port_ready = &s_rt->slave->port_ready[prep_ch.num];
> -		time_left = wait_for_completion_timeout(port_ready,
> -				msecs_to_jiffies(dpn_prop->ch_prep_timeout));
> +		wait_for_completion_timeout(port_ready,
> +			msecs_to_jiffies(dpn_prop->ch_prep_timeout));
>  
>  		val = sdw_read(s_rt->slave, SDW_DPN_PREPARESTATUS(p_rt->num));
> -		val &= p_rt->ch_mask;
> -		if (!time_left || val) {
> +		if ((val < 0) || (val & p_rt->ch_mask)) {
> +			ret = (val < 0) ? val : -ETIMEDOUT;
>  			dev_err(&s_rt->slave->dev,
> -				"Chn prep failed for port:%d\n", prep_ch.num);
> -			return -ETIMEDOUT;
> +				"Chn prep failed for port %d: %d\n", prep_ch.num, ret);
> +			return ret;
>  		}
>  	}
>  
>