Re: [RFC PATCH 17/40] soundwire: bus: use runtime_pm_get_sync/pm when enabled

[Pierre-Louis Bossart]

This thread became unreadable with interleaved top-posting, allow me 
restate the options and ask PM folks what they think

On 7/25/19 6:40 PM, Pierre-Louis Bossart wrote:
Not all platforms support runtime_pm for now, let's use runtime_pm
only when enabled.
Suggested-by: Srinivas Kandagatla <srinivas.kandaga...@linaro.org>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.boss...@linux.intel.com>
---
  drivers/soundwire/bus.c | 25 ++++++++++++++++---------
  1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 5ad4109dc72f..0a45dc5713df 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -332,12 +332,16 @@ int sdw_nread(struct sdw_slave *slave, u32 addr, size_t 
count, u8 *val)
        if (ret < 0)
                return ret;
  
-	ret = pm_runtime_get_sync(slave->bus->dev);
-       if (ret < 0)
-               return ret;
+       if (pm_runtime_enabled(slave->bus->dev)) {
+               ret = pm_runtime_get_sync(slave->bus->dev);
+               if (ret < 0)
+                       return ret;
+       }
  
  	ret = sdw_transfer(slave->bus, &msg);
-       pm_runtime_put(slave->bus->dev);
+
+       if (pm_runtime_enabled(slave->bus->dev))
+               pm_runtime_put(slave->bus->dev);

This is option1: we explicitly test if pm_runtime is enabled before 
calling _get_sync() and _put()

option2 (suggested by Jan Kotas): catch the -EACCESS error code

        ret = pm_runtime_get_sync(slave->bus->dev);
-       if (ret < 0)
+       if (ret < 0 && ret != -EACCES)
                return ret;

option3: ignore the return value as done in quite a few drivers

Are there any other options? I am personally surprised this is not 
handled in the pm_runtime core, not sure why users need to test for this?

Thanks
Pierre