| Message ID | 20210421120512.413057-6-jbrunet@baylibre.com |
|---|---|
| State | Accepted |
| Commit | 12f8127fe9e6154dd4197df97e44f3fd67583071 |
| Headers | show |
| Series | None | expand |
On 4/21/21 7:05 AM, Jerome Brunet wrote: > Instead of using the clk embedded in the clk_hw (which is meant to go > away), a clock provider which need to interact with its own clock should > request clk reference through the clock provider API. > > Reviewed-by: Stephen Boyd <sboyd@kernel.org> > Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> This patch seems to introduce a regression in our modprobe/rmmod tests https://github.com/thesofproject/linux/pull/2870 RMMOD snd_soc_da7219 rmmod: ERROR: Module snd_soc_da7219 is in use Reverting this patch restores the ability to remove the module. Wondering if devm_ increases a module/device refcount somehow? > --- > sound/soc/codecs/da7219.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/sound/soc/codecs/da7219.c b/sound/soc/codecs/da7219.c > index 13009d08b09a..bd3c523a8617 100644 > --- a/sound/soc/codecs/da7219.c > +++ b/sound/soc/codecs/da7219.c > @@ -2181,7 +2181,10 @@ static int da7219_register_dai_clks(struct snd_soc_component *component) > ret); > goto err; > } > - da7219->dai_clks[i] = dai_clk_hw->clk; > + > + da7219->dai_clks[i] = devm_clk_hw_get_clk(dev, dai_clk_hw, NULL); > + if (IS_ERR(da7219->dai_clks[i])) > + return PTR_ERR(da7219->dai_clks[i]); > > /* For DT setup onecell data, otherwise create lookup */ > if (np) { >
> On 4/21/21 7:05 AM, Jerome Brunet wrote: >> Instead of using the clk embedded in the clk_hw (which is meant to go >> away), a clock provider which need to interact with its own clock should >> request clk reference through the clock provider API. >> >> Reviewed-by: Stephen Boyd <sboyd@kernel.org> >> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> > > This patch seems to introduce a regression in our modprobe/rmmod tests > > https://github.com/thesofproject/linux/pull/2870 > > RMMOD snd_soc_da7219 > rmmod: ERROR: Module snd_soc_da7219 is in use > > Reverting this patch restores the ability to remove the module. > > Wondering if devm_ increases a module/device refcount somehow? the following diff fixes the issue for me There is an explicit try_module_get() in clk_hw_create_clk, so you end-up increasing the refcount of your own module. devm_ doesn't seem like a good idea here, I think we have to release the clk and its implicit module reference when the component is freed, no? I can send a proper fix if there is consensus. diff --git a/sound/soc/codecs/da7219.c b/sound/soc/codecs/da7219.c index bd3c523a8617..8696ac749af3 100644 --- a/sound/soc/codecs/da7219.c +++ b/sound/soc/codecs/da7219.c @@ -2182,7 +2182,7 @@ static int da7219_register_dai_clks(struct snd_soc_component *component) goto err; } - da7219->dai_clks[i] = devm_clk_hw_get_clk(dev, dai_clk_hw, NULL); + da7219->dai_clks[i] = clk_hw_get_clk(dai_clk_hw, NULL); if (IS_ERR(da7219->dai_clks[i])) return PTR_ERR(da7219->dai_clks[i]); @@ -2218,6 +2218,8 @@ static int da7219_register_dai_clks(struct snd_soc_component *component) if (da7219->dai_clks_lookup[i]) clkdev_drop(da7219->dai_clks_lookup[i]); + clk_put(da7219->dai_clks[i]); + clk_hw_unregister(&da7219->dai_clks_hw[i]); } while (i-- > 0); @@ -2240,6 +2242,8 @@ static void da7219_free_dai_clks(struct snd_soc_component *component) if (da7219->dai_clks_lookup[i]) clkdev_drop(da7219->dai_clks_lookup[i]); + clk_put(da7219->dai_clks[i]); + clk_hw_unregister(&da7219->dai_clks_hw[i]); }
On Mon 26 Apr 2021 at 20:10, Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> wrote: > On 4/21/21 7:05 AM, Jerome Brunet wrote: >> Instead of using the clk embedded in the clk_hw (which is meant to go >> away), a clock provider which need to interact with its own clock should >> request clk reference through the clock provider API. >> Reviewed-by: Stephen Boyd <sboyd@kernel.org> >> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> > > This patch seems to introduce a regression in our modprobe/rmmod tests Really sorry about that :/ > > https://github.com/thesofproject/linux/pull/2870 > > RMMOD snd_soc_da7219 > rmmod: ERROR: Module snd_soc_da7219 is in use > > Reverting this patch restores the ability to remove the module. > > Wondering if devm_ increases a module/device refcount somehow? The driver is the provider and consumer, so it is consuming itself. This was the intent, I think the patch should be correct like this. Maybe I overlooked something on the clock side. I'll check. I'm not sure the problem is devm_ variant, it might be clk_hw_get_clk() simpler variant which also plays with module ref counts. I don't have this particular HW to check but I'll try to replicate the test with a dummy module and report ASAP. Of course, I suppose the same problem applies to PATCH 1 of the series > >> --- >> sound/soc/codecs/da7219.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> diff --git a/sound/soc/codecs/da7219.c b/sound/soc/codecs/da7219.c >> index 13009d08b09a..bd3c523a8617 100644 >> --- a/sound/soc/codecs/da7219.c >> +++ b/sound/soc/codecs/da7219.c >> @@ -2181,7 +2181,10 @@ static int da7219_register_dai_clks(struct snd_soc_component *component) >> ret); >> goto err; >> } >> - da7219->dai_clks[i] = dai_clk_hw->clk; >> + >> + da7219->dai_clks[i] = devm_clk_hw_get_clk(dev, dai_clk_hw, NULL); >> + if (IS_ERR(da7219->dai_clks[i])) >> + return PTR_ERR(da7219->dai_clks[i]); >> /* For DT setup onecell data, otherwise create lookup */ >> if (np) { >>
On Mon 26 Apr 2021 at 21:35, Jerome Brunet <jbrunet@baylibre.com> wrote: > On Mon 26 Apr 2021 at 20:10, Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> wrote: > >> On 4/21/21 7:05 AM, Jerome Brunet wrote: >>> Instead of using the clk embedded in the clk_hw (which is meant to go >>> away), a clock provider which need to interact with its own clock should >>> request clk reference through the clock provider API. >>> Reviewed-by: Stephen Boyd <sboyd@kernel.org> >>> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> >> >> This patch seems to introduce a regression in our modprobe/rmmod tests > > Really sorry about that :/ > >> >> https://github.com/thesofproject/linux/pull/2870 >> >> RMMOD snd_soc_da7219 >> rmmod: ERROR: Module snd_soc_da7219 is in use >> >> Reverting this patch restores the ability to remove the module. >> >> Wondering if devm_ increases a module/device refcount somehow? > > The driver is the provider and consumer, so it is consuming itself. > This was the intent, I think the patch should be correct like > this. Maybe I overlooked something on the clock side. I'll check. > > I'm not sure the problem is devm_ variant, it might be > clk_hw_get_clk() simpler variant which also plays with module ref counts. > > I don't have this particular HW to check but I'll try to replicate the > test with a dummy module and report ASAP. > > Of course, I suppose the same problem applies to PATCH 1 of the series So I can confirm that the problem is in CCF and the function clk_hw_get_clk() which pins the clocks provider to itself. Not that many clock providers are modules and even less are getting removed. This is probably why this fundamental issue has not been detected before. Thanks a lot for reporting it. Mark, at this point I think it would be best to revert patches 1 and 5 while we work this out in CCF. The other patches are not affected. Sorry for the mess.
On Tue, Apr 27, 2021 at 11:16:25AM +0200, Jerome Brunet wrote: > Mark, at this point I think it would be best to revert patches 1 and 5 > while we work this out in CCF. The other patches are not affected. > Sorry for the mess. Sure, can someone send a patch with a changelog explaining the issue please?
On Tue 27 Apr 2021 at 12:27, Mark Brown <broonie@kernel.org> wrote: > On Tue, Apr 27, 2021 at 11:16:25AM +0200, Jerome Brunet wrote: > >> Mark, at this point I think it would be best to revert patches 1 and 5 >> while we work this out in CCF. The other patches are not affected. >> Sorry for the mess. > > Sure, can someone send a patch with a changelog explaining the issue > please? Will do
diff --git a/sound/soc/codecs/da7219.c b/sound/soc/codecs/da7219.c index 13009d08b09a..bd3c523a8617 100644 --- a/sound/soc/codecs/da7219.c +++ b/sound/soc/codecs/da7219.c @@ -2181,7 +2181,10 @@ static int da7219_register_dai_clks(struct snd_soc_component *component) ret); goto err; } - da7219->dai_clks[i] = dai_clk_hw->clk; + + da7219->dai_clks[i] = devm_clk_hw_get_clk(dev, dai_clk_hw, NULL); + if (IS_ERR(da7219->dai_clks[i])) + return PTR_ERR(da7219->dai_clks[i]); /* For DT setup onecell data, otherwise create lookup */ if (np) {