From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guennadi Liakhovetski Subject: Re: [alsa-devel] [RFC PATCH 17/40] soundwire: bus: use runtime_pm_get_sync/pm when enabled Date: Fri, 26 Jul 2019 20:25:35 +0200 Message-ID: <20190726182534.GO16003@ubuntu> References: <20190725234032.21152-1-pierre-louis.bossart@linux.intel.com> <20190725234032.21152-18-pierre-louis.bossart@linux.intel.com> <45a912c5-134b-8642-70ef-8c1060389300@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <45a912c5-134b-8642-70ef-8c1060389300@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org To: Pierre-Louis Bossart Cc: alsa-devel@alsa-project.org, "Rafael J. Wysocki" , tiwai@suse.de, gregkh@linuxfoundation.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, vkoul@kernel.org, broonie@kernel.org, srinivas.kandagatla@linaro.org, jank@cadence.com, slawomir.blauciak@intel.com, Sanyog Kale , Andy Shevchenko List-Id: alsa-devel@alsa-project.org On Fri, Jul 26, 2019 at 01:08:57PM -0500, Pierre-Louis Bossart wrote: > 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 > > Signed-off-by: Pierre-Louis Bossart > > --- > > 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? option 4: fix this in runtime PM :-) This seems like the best option to me, but probably not the easiest one. Otherwise I'd go with (2), I think, since that's also the official purpose of the -EACCESS return code: https://lists.linuxfoundation.org/pipermail/linux-pm/2011-June/031930.html Thanks Guennadi