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SubjectRe: [PATCH 1/7] soundwire: bus: use sdw_update_no_pm when initializing a device
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Thanks for the review Vinod.

On 12/5/20 1:45 AM, Vinod Koul wrote:
> On 03-12-20, 04:46, Bard Liao wrote:
>> From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
>>
>> When a Slave device is resumed, it may resume the bus and restart the
>> enumeration. During that process, we absolutely don't want to call
>> regular read/write routines which will wait for the resume to
>> complete, otherwise a deadlock occurs.
>>
>> Fixes: 60ee9be25571 ('soundwire: bus: add PM/no-PM versions of read/write functions')
>
> Change looks okay, but not sure why this is a fix for adding no pm
> version?

when we added the no_pm version, we missed the two cases below where
sdw_update() was used and that creates a deadlock. To me that's a
conceptual bug, we didn't fully use the no_pm versions, hence the Fixes tag.

It's ok to remove the tag if you don't think it's useful/relevant, what
matters is that we agree on the content.

>> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
>> Reviewed-by: Rander Wang <rander.wang@linux.intel.com>
>> Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
>> ---
>> drivers/soundwire/bus.c | 16 ++++++++++++++--
>> 1 file changed, 14 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
>> index d1e8c3a54976..60c42508c6c6 100644
>> --- a/drivers/soundwire/bus.c
>> +++ b/drivers/soundwire/bus.c
>> @@ -489,6 +489,18 @@ sdw_read_no_pm(struct sdw_slave *slave, u32 addr)
>> return buf;
>> }
>>
>> +static int sdw_update_no_pm(struct sdw_slave *slave, u32 addr, u8 mask, u8 val)
>> +{
>> + int tmp;
>> +
>> + tmp = sdw_read_no_pm(slave, addr);
>> + if (tmp < 0)
>> + return tmp;
>> +
>> + tmp = (tmp & ~mask) | val;
>> + return sdw_write_no_pm(slave, addr, tmp);
>> +}
>> +
>> /**
>> * sdw_nread() - Read "n" contiguous SDW Slave registers
>> * @slave: SDW Slave
>> @@ -1256,7 +1268,7 @@ static int sdw_initialize_slave(struct sdw_slave *slave)
>> val = slave->prop.scp_int1_mask;
>>
>> /* Enable SCP interrupts */
>> - ret = sdw_update(slave, SDW_SCP_INTMASK1, val, val);
>> + ret = sdw_update_no_pm(slave, SDW_SCP_INTMASK1, val, val);
>> if (ret < 0) {
>> dev_err(slave->bus->dev,
>> "SDW_SCP_INTMASK1 write failed:%d\n", ret);
>> @@ -1271,7 +1283,7 @@ static int sdw_initialize_slave(struct sdw_slave *slave)
>> val = prop->dp0_prop->imp_def_interrupts;
>> val |= SDW_DP0_INT_PORT_READY | SDW_DP0_INT_BRA_FAILURE;
>>
>> - ret = sdw_update(slave, SDW_DP0_INTMASK, val, val);
>> + ret = sdw_update_no_pm(slave, SDW_DP0_INTMASK, val, val);
>> if (ret < 0)
>> dev_err(slave->bus->dev,
>> "SDW_DP0_INTMASK read failed:%d\n", ret);
>> --
>> 2.17.1
>

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