When PM is disabled it returns -EACCES, which is currently
threated as an error, and prevents accessing the slave's
registers.
This patch ignores the -EACCES return value from
pm_runtime_get_sync() to let the SoundWire work in systems
without runtime PM.
Signed-off-by: Jan Kotas <[email protected]>
---
drivers/soundwire/bus.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 1cbfedfc2..6567ff439 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -328,7 +328,7 @@ int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
return ret;
ret = pm_runtime_get_sync(slave->bus->dev);
- if (ret < 0)
+ if (ret < 0 && ret != -EACCES)
return ret;
ret = sdw_transfer(slave->bus, &msg);
@@ -356,7 +356,7 @@ int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
return ret;
ret = pm_runtime_get_sync(slave->bus->dev);
- if (ret < 0)
+ if (ret < 0 && ret != -EACCES)
return ret;
ret = sdw_transfer(slave->bus, &msg);
--
2.15.0
> On 5 Apr 2019, at 17:04, Pierre-Louis Bossart <[email protected]> wrote:
>
> On 4/5/19 2:26 AM, Jan Kotas wrote:
>>
>>
>> ret = pm_runtime_get_sync(slave->bus->dev);
>> - if (ret < 0)
>> + if (ret < 0 && ret != -EACCES)
>>
> There was a patch submitted on 3/28 by Srinivas Kandagatla who suggested an alternate solution for exactly the same code.
>
> + if (pm_runtime_enabled(slave->bus->dev)) {
> + ret = pm_runtime_get_sync(slave->bus->dev);
> + if (ret < 0)
> + return ret;
>
> I am far from an expert on pm_runtime but Srinivas' solution looks more elegant to me.
Hello Pierre,
Please take a look at this patch, that was my inspiration:
https://lists.linuxfoundation.org/pipermail/linux-pm/2011-June/031930.html
I also took a look, and it seems the value returned by
pm_runtime_get_syncis simply ignored in a lot of places,
so checking its value may be excessive.
Regards,
Jan
On 4/8/19 2:12 AM, Jan Kotas wrote:
>
>
>> On 5 Apr 2019, at 17:04, Pierre-Louis Bossart <[email protected]> wrote:
>>
>> On 4/5/19 2:26 AM, Jan Kotas wrote:
>>>
>>>
>>> ret = pm_runtime_get_sync(slave->bus->dev);
>>> - if (ret < 0)
>>> + if (ret < 0 && ret != -EACCES)
>>>
>> There was a patch submitted on 3/28 by Srinivas Kandagatla who suggested an alternate solution for exactly the same code.
>>
>> + if (pm_runtime_enabled(slave->bus->dev)) {
>> + ret = pm_runtime_get_sync(slave->bus->dev);
>> + if (ret < 0)
>> + return ret;
>>
>> I am far from an expert on pm_runtime but Srinivas' solution looks more elegant to me.
>
> Hello Pierre,
>
> Please take a look at this patch, that was my inspiration:
> https://lists.linuxfoundation.org/pipermail/linux-pm/2011-June/031930.html
The two patches seems to be identical:
static inline bool pm_runtime_enabled(struct device *dev)
{
return !dev->power.disable_depth;
}
static int rpm_resume()
[...]
else if (dev->power.disable_depth > 0)
retval = -EACCES;
However I am still not clear on why this might fail.
I can only think of one possible explanation: there is no explicit
pm_runtime_enable() in the soundwire code, so maybe the expectation is
that the pm_runtime status is inherited from the parent (in the intel
case the PCI driver), and that's missing in non-intel configurations?
> I also took a look, and it seems the value returned by
> pm_runtime_get_syncis simply ignored in a lot of places,
> so checking its value may be excessive.
But not checking seems careless at best...
On 08-04-19, 12:43, Pierre-Louis Bossart wrote:
>
>
> On 4/8/19 2:12 AM, Jan Kotas wrote:
> >
> >
> > > On 5 Apr 2019, at 17:04, Pierre-Louis Bossart <[email protected]> wrote:
> > >
> > > On 4/5/19 2:26 AM, Jan Kotas wrote:
> > > >
> > > > ret = pm_runtime_get_sync(slave->bus->dev);
> > > > - if (ret < 0)
> > > > + if (ret < 0 && ret != -EACCES)
> > > >
> > > There was a patch submitted on 3/28 by Srinivas Kandagatla who suggested an alternate solution for exactly the same code.
> > >
> > > + if (pm_runtime_enabled(slave->bus->dev)) {
> > > + ret = pm_runtime_get_sync(slave->bus->dev);
> > > + if (ret < 0)
> > > + return ret;
> > >
> > > I am far from an expert on pm_runtime but Srinivas' solution looks more elegant to me.
> >
> > Hello Pierre,
> >
> > Please take a look at this patch, that was my inspiration:
> > https://lists.linuxfoundation.org/pipermail/linux-pm/2011-June/031930.html
>
> The two patches seems to be identical:
>
> static inline bool pm_runtime_enabled(struct device *dev)
> {
> return !dev->power.disable_depth;
> }
>
> static int rpm_resume()
> [...]
> else if (dev->power.disable_depth > 0)
> retval = -EACCES;
>
>
> However I am still not clear on why this might fail.
>
> I can only think of one possible explanation: there is no explicit
> pm_runtime_enable() in the soundwire code, so maybe the expectation is that
> the pm_runtime status is inherited from the parent (in the intel case the
> PCI driver), and that's missing in non-intel configurations?
IIRC that needs to be called by the Intel driver and those patches were
not upstreamed. So we dont have fully supported PM on upstream yet!
>
> > I also took a look, and it seems the value returned by
> > pm_runtime_get_syncis simply ignored in a lot of places,
> > so checking its value may be excessive.
> But not checking seems careless at best...
--
~Vinod