Re: [alsa-devel] [PATCH 1/6] soundwire: fix startup sequence for Intel/Cadence

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

On 9/4/19 2:11 AM, Vinod Koul wrote:
> On 13-08-19, 16:32, Pierre-Louis Bossart wrote:
>> Multiple changes squashed in single patch to avoid tick-tock effect.
>>
>> 1. Per the hardware documentation, all changes to MCP_CONFIG,
>> MCP_CONTROL, MCP_CMDCTRL and MCP_PHYCTRL need to be validated with a
>> self-clearing write to MCP_CONFIG_UPDATE. Add a helper and do the
>> update when the CONFIG is changed.
>>
>> 2. Move interrupt enable after interrupt handler registration
>>
>> 3. Add a new helper to start the 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.
>>
>> 4. flush command FIFOs
>>
>> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
>> ---
>>   drivers/soundwire/cadence_master.c | 84 +++++++++++++++++++++---------
>>   drivers/soundwire/cadence_master.h |  1 +
>>   drivers/soundwire/intel.c          | 14 ++++-
>>   3 files changed, 73 insertions(+), 26 deletions(-)
>>
>> diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
>> index 502ed4ec8f07..046622e4b264 100644
>> --- a/drivers/soundwire/cadence_master.c
>> +++ b/drivers/soundwire/cadence_master.c
>> @@ -231,6 +231,22 @@ static int cdns_clear_bit(struct sdw_cdns *cdns, int offset, u32 value)
>>   	return -EAGAIN;
>>   }
>>   
>> +/*
>> + * all changes to the MCP_CONFIG, MCP_CONTROL, MCP_CMDCTRL and MCP_PHYCTRL
>> + * need to be confirmed with a write to MCP_CONFIG_UPDATE
>> + */
>> +static int cdns_update_config(struct sdw_cdns *cdns)
>> +{
>> +	int ret;
>> +
>> +	ret = cdns_clear_bit(cdns, CDNS_MCP_CONFIG_UPDATE,
>> +			     CDNS_MCP_CONFIG_UPDATE_BIT);
>> +	if (ret < 0)
>> +		dev_err(cdns->dev, "Config update timedout\n");
>> +
>> +	return ret;
>> +}
>> +
>>   /*
>>    * debugfs
>>    */
>> @@ -752,7 +768,42 @@ EXPORT_SYMBOL(sdw_cdns_thread);
>>   /*
>>    * init routines
>>    */
>> -static int _cdns_enable_interrupt(struct sdw_cdns *cdns)
>> +
>> +/**
>> + * sdw_cdns_exit_reset() - Program reset parameters and start bus operations
>> + * @cdns: Cadence instance
>> + */
>> +int sdw_cdns_exit_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() ?

ok

> 
> 
>> +}
>> +EXPORT_SYMBOL(sdw_cdns_exit_reset);
>> +
>> +/**
>> + * sdw_cdns_enable_interrupt() - Enable SDW interrupts and update config
>> + * @cdns: Cadence instance
>> + */
>> +int sdw_cdns_enable_interrupt(struct sdw_cdns *cdns)
>>   {
>>   	u32 mask;
>>   
>> @@ -784,24 +835,8 @@ static int _cdns_enable_interrupt(struct sdw_cdns *cdns)
>>   
>>   	cdns_writel(cdns, CDNS_MCP_INTMASK, mask);
>>   
>> -	return 0;
>> -}
>> -
>> -/**
>> - * sdw_cdns_enable_interrupt() - Enable SDW interrupts and update config
>> - * @cdns: Cadence instance
>> - */
>> -int sdw_cdns_enable_interrupt(struct sdw_cdns *cdns)
>> -{
>> -	int ret;
>> -
>> -	_cdns_enable_interrupt(cdns);
>> -	ret = cdns_clear_bit(cdns, CDNS_MCP_CONFIG_UPDATE,
>> -			     CDNS_MCP_CONFIG_UPDATE_BIT);
>> -	if (ret < 0)
>> -		dev_err(cdns->dev, "Config update timedout\n");
>> -
>> -	return ret;
>> +	/* commit changes */
>> +	return cdns_update_config(cdns);
>>   }
>>   EXPORT_SYMBOL(sdw_cdns_enable_interrupt);
>>   
>> @@ -975,6 +1010,10 @@ 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);
>> @@ -997,13 +1036,10 @@ 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);
>>   
>> -	return 0;
>> +	/* commit changes */
>> +	return cdns_update_config(cdns);
>>   }
>>   EXPORT_SYMBOL(sdw_cdns_init);
>>   
>> diff --git a/drivers/soundwire/cadence_master.h b/drivers/soundwire/cadence_master.h
>> index 0b72b7094735..1a67728c5000 100644
>> --- a/drivers/soundwire/cadence_master.h
>> +++ b/drivers/soundwire/cadence_master.h
>> @@ -161,6 +161,7 @@ irqreturn_t sdw_cdns_thread(int irq, void *dev_id);
>>   int sdw_cdns_init(struct sdw_cdns *cdns);
>>   int sdw_cdns_pdi_init(struct sdw_cdns *cdns,
>>   		      struct sdw_cdns_stream_config config);
>> +int sdw_cdns_exit_reset(struct sdw_cdns *cdns);
>>   int sdw_cdns_enable_interrupt(struct sdw_cdns *cdns);
>>   
>>   #ifdef CONFIG_DEBUG_FS
>> diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
>> index 13c54eac0cc3..5f14c6acce80 100644
>> --- a/drivers/soundwire/intel.c
>> +++ b/drivers/soundwire/intel.c
> 
> As I have said in the past it doesnt help having a patch touching two
> components. The patch is titled cadence!

no, it's called 'fix startup sequence for Intel/Cadence' and it's 
intentional to modify the two parts in a single patch.
I tried to split this but it's very difficult due to the dependencies. 
If you look at all the initial comments from early July people were lost 
when I did these changes in steps. I try to keep patches local and 
self-contained, but in this case it's nearly impossible or makes the 
review very hard for no good reason.

> 
>> @@ -1043,8 +1043,6 @@ static int intel_probe(struct platform_device *pdev)
>>   	if (ret)
>>   		goto err_init;
>>   
>> -	ret = sdw_cdns_enable_interrupt(&sdw->cdns);
>> -
>>   	/* Read the PDI config and initialize cadence PDI */
>>   	intel_pdi_init(sdw, &config);
>>   	ret = sdw_cdns_pdi_init(&sdw->cdns, config);
>> @@ -1062,6 +1060,18 @@ static int intel_probe(struct platform_device *pdev)
>>   		goto err_init;
>>   	}
>>   
>> +	ret = sdw_cdns_enable_interrupt(&sdw->cdns);
>> +	if (ret < 0) {
>> +		dev_err(sdw->cdns.dev, "cannot enable interrupts\n");
>> +		goto err_init;
>> +	}
>> +
>> +	ret = sdw_cdns_exit_reset(&sdw->cdns);
>> +	if (ret < 0) {
>> +		dev_err(sdw->cdns.dev, "unable to exit bus reset sequence\n");
>> +		goto err_init;
> 
> Don't you want to disable interrupts at least... before you return
> error? err_init does bus cleanup and not controller one

yes good point, let me look at this.