On 8/21/23 09:57, Takashi Iwai wrote: > On Mon, 21 Aug 2023 16:43:31 +0200, > Pierre-Louis Bossart wrote: >> >> >>>>> +static void tas2781_hda_playback_hook(struct device *dev, int action) >>>>> +{ >>>>> + struct tasdevice_priv *tas_priv = dev_get_drvdata(dev); >>>>> + >>>>> + dev_dbg(tas_priv->dev, "%s: action = %d\n", __func__, action); >>>>> + switch (action) { >>>>> + case HDA_GEN_PCM_ACT_OPEN: >>>>> + pm_runtime_get_sync(dev); >>>> >>>> test if this actually works? >>> >>> To be fair, most of driver codes don't check it, including the >>> HD-audio core. (Actually, over 900 of 1300 calls have no check in the >>> whole tree.) >>> >>> It implies that forcing the check in each place is moot; rather the >>> helper needs to be coded not to fail, IMO. >> >> Maybe that's true for HDaudio, for the SoundWire parts we absolutely >> need to detect if the resume worked. There are more steps involved, the >> clock-stop mode entry/exit, context restoration, re-enumeration, etc. >> >> I think it'd be a mistake to sit on our hands and assume the world is >> perfect. We have to track cases where the codec isn't properly resumed >> and prevent it from accessing resources that are just unavailable. > > Yeah, I don't mean that it's wrong or bad to have the check. The > check should be there. > > But, I feel that it's time to rather switch to the proper call. > Basically pm_runtime_resume_and_get() is the better alternative > (except for its long naming), and we may think of converting the > whole. Oh, I broke so many drivers by trying a well-indented conversion to pm_runtime_resume_and_get(). The flow is different wrt -EACCESs and we ended-up with multiple errors. In hindsight I wish we had left the legacy code alone. >>>>> +static int tas2781_system_suspend(struct device *dev) >>>>> +{ >>>>> + struct tasdevice_priv *tas_priv = dev_get_drvdata(dev); >>>>> + int ret; >>>>> + >>>>> + dev_dbg(tas_priv->dev, "System Suspend\n"); >>>>> + >>>>> + ret = pm_runtime_force_suspend(dev); >>>>> + if (ret) >>>>> + return ret; >>>> >>>> that's usually the other way around, for system suspend you either want >>>> the device to be pm_runtime active, or if it's already suspended do nothing. >>>> >>>> This is very odd to me. >>> >>> This is a normal procedure, as stated in pm_runtime_force_suspend() >>> definition: >>> >>> /** >>> * pm_runtime_force_suspend - Force a device into suspend state if needed. >>> .... >>> * Typically this function may be invoked from a system suspend callback to make >>> * sure the device is put into low power state and it should only be used during >>> * system-wide PM transitions to sleep states. It assumes that the analogous >>> * pm_runtime_force_resume() will be used to resume the device. >> >> It's possible that it's fine for HDaudio, it wouldn't work in all cases >> for SoundWire where we have to make sure all pm_runtime suspended >> devices are brought back to D0 and then the regular system suspend >> happens. That's mainly because pm_runtime suspend relies on clock stop >> and system suspend does not. >> >> In other words, this isn't a generic solution at all. > > Well, I suppose rather that soundwire is an exception :) > > For majority of devices, the system suspend/resume is nothing but > pm_runtime_force_*() calls. e.g. take a look at > DEFINE_RUNTIME_DEV_PM_OPS() in linux/pm_runtime.h. I guess you are right. SoundWire has indeed these quirky modes and differences between SOC vendors that will force us to be extra careful in what the codec driver implements.