linux-kernel - Re: [alsa-devel] [RFC PATCH 15/40] soundwire: cadence_master: handle multiple status reports per Slave

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Message-ID: <20190725223100.GC16003@ubuntu>
Date:   Fri, 26 Jul 2019 00:31:01 +0200
From:   Guennadi Liakhovetski <guennadi.liakhovetski@...ux.intel.com>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     alsa-devel@...a-project.org, 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 15/40] soundwire: cadence_master: handle
 multiple status reports per Slave

On Thu, Jul 25, 2019 at 06:40:07PM -0500, Pierre-Louis Bossart wrote:
> When a Slave reports multiple status in the sticky bits, find the
> latest configuration from the mirror of the PING frame status and
> update the status directly.
> 
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> ---
>  drivers/soundwire/cadence_master.c | 34 ++++++++++++++++++++++++------
>  1 file changed, 28 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
> index 889fa2cd49ae..25d5c7267c15 100644
> --- a/drivers/soundwire/cadence_master.c
> +++ b/drivers/soundwire/cadence_master.c
> @@ -643,13 +643,35 @@ static int cdns_update_slave_status(struct sdw_cdns *cdns,
>  
>  		/* first check if Slave reported multiple status */
>  		if (set_status > 1) {
> +			u32 val;
> +
>  			dev_warn_ratelimited(cdns->dev,
> -					     "Slave reported multiple Status: %d\n",
> -					     mask);
> -			/*
> -			 * TODO: we need to reread the status here by
> -			 * issuing a PING cmd
> -			 */
> +					     "Slave %d reported multiple Status: %d\n",
> +					     i, mask);
> +
> +			/* re-check latest status extracted from PING commands */
> +			val = cdns_readl(cdns, CDNS_MCP_SLAVE_STAT);
> +			val >>= (i * 2);

Superfluous parentheses.

> +
> +			switch (val & 0x3) {
> +			case 0:
> +				status[i] = SDW_SLAVE_UNATTACHED;
> +				break;
> +			case 1:
> +				status[i] = SDW_SLAVE_ATTACHED;
> +				break;
> +			case 2:
> +				status[i] = SDW_SLAVE_ALERT;
> +				break;
> +			default:

There aren't many values left for the "default" case :-) But I'm not sure whether
any of

+			case 3:

or

+			case 3:
+			default:

would improve readability.

Thanks
Guennadi

> +				status[i] = SDW_SLAVE_RESERVED;
> +				break;
> +			}
> +
> +			dev_warn_ratelimited(cdns->dev,
> +					     "Slave %d status updated to %d\n",
> +					     i, status[i]);
> +
>  		}
>  	}
>  
> -- 
> 2.20.1
> 
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel@...a-project.org
> https://mailman.alsa-project.org/mailman/listinfo/alsa-devel

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