| Message ID | 1597831670-17401-2-git-send-email-mkshah@codeaurora.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Modularize RPMH driver | expand |
Quoting Maulik Shah (2020-08-19 03:07:49) > This change was done based on an test results of unmerged series of > adding RSC power domain and using .power_off callback of genpd to > invoke rpmh_flush(). Perhaps: Commit efde2659b0fe ("drivers: qcom: rpmh-rsc: Use rcuidle tracepoints for rpmh") was written to fix a bug seen in an unmerged series that implemented a struct generic_pm_domain::power_off() callback calling rpmh_flush(). See stack trace below. > > Call trace: > dump_backtrace+0x0/0x174 > show_stack+0x20/0x2c > dump_stack+0xc8/0x124 > lockdep_rcu_suspicious+0xe4/0x104 > __tcs_buffer_write+0x230/0x2d0 > rpmh_rsc_write_ctrl_data+0x210/0x270 > rpmh_flush+0x84/0x24c > rpmh_domain_power_off+0x78/0x98 > _genpd_power_off+0x40/0xc0 > genpd_power_off+0x168/0x208 > > Later the final merged solution is to use CPU PM notification to invoke > rpmh_flush() and .power_off callback of genpd is not implemented in the > driver. I'd also add: CPU PM notifiers are run with RCU enabled/watching (see cpu_pm_notify() and how it calls rcu_irq_enter_irqson() before calling the notifiers). > > Remove this change since RCU will not be idle during CPU PM notifications > hence not required to use _rcuidle tracepoint. Using _rcuidle tracepoint > prevented rpmh driver to be loadable module as these are not exported > symbols. > > This reverts commit efde2659b0fe835732047357b2902cca14f054d9. > > Cc: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> > Cc: John Stultz <john.stultz@linaro.org> > Cc: Stephen Rothwell <sfr@canb.auug.org.au> > Signed-off-by: Maulik Shah <mkshah@codeaurora.org> > --- Otherwise Reviewed-by: Stephen Boyd <swboyd@chromium.org>
On 2020-08-19 15:37, Maulik Shah wrote: > This change was done based on an test results of unmerged series of > adding RSC power domain and using .power_off callback of genpd to > invoke rpmh_flush(). > > Call trace: > dump_backtrace+0x0/0x174 > show_stack+0x20/0x2c > dump_stack+0xc8/0x124 > lockdep_rcu_suspicious+0xe4/0x104 > __tcs_buffer_write+0x230/0x2d0 > rpmh_rsc_write_ctrl_data+0x210/0x270 > rpmh_flush+0x84/0x24c > rpmh_domain_power_off+0x78/0x98 > _genpd_power_off+0x40/0xc0 > genpd_power_off+0x168/0x208 > > Later the final merged solution is to use CPU PM notification to invoke > rpmh_flush() and .power_off callback of genpd is not implemented in the > driver. > > Remove this change since RCU will not be idle during CPU PM > notifications > hence not required to use _rcuidle tracepoint. Using _rcuidle > tracepoint > prevented rpmh driver to be loadable module as these are not exported > symbols. > > This reverts commit efde2659b0fe835732047357b2902cca14f054d9. > > Cc: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> > Cc: John Stultz <john.stultz@linaro.org> > Cc: Stephen Rothwell <sfr@canb.auug.org.au> > Signed-off-by: Maulik Shah <mkshah@codeaurora.org> > --- Reviewed-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> Thanks, Sai
Hi, On 8/19/2020 11:34 PM, Stephen Boyd wrote: > Quoting Maulik Shah (2020-08-19 03:07:49) >> This change was done based on an test results of unmerged series of >> adding RSC power domain and using .power_off callback of genpd to >> invoke rpmh_flush(). > Perhaps: > > Commit efde2659b0fe ("drivers: qcom: rpmh-rsc: Use rcuidle tracepoints > for rpmh") was written to fix a bug seen in an unmerged series that > implemented a struct generic_pm_domain::power_off() callback calling > rpmh_flush(). See stack trace below. Sure i will update in v2. > >> Call trace: >> dump_backtrace+0x0/0x174 >> show_stack+0x20/0x2c >> dump_stack+0xc8/0x124 >> lockdep_rcu_suspicious+0xe4/0x104 >> __tcs_buffer_write+0x230/0x2d0 >> rpmh_rsc_write_ctrl_data+0x210/0x270 >> rpmh_flush+0x84/0x24c >> rpmh_domain_power_off+0x78/0x98 >> _genpd_power_off+0x40/0xc0 >> genpd_power_off+0x168/0x208 >> >> Later the final merged solution is to use CPU PM notification to invoke >> rpmh_flush() and .power_off callback of genpd is not implemented in the >> driver. > I'd also add: > > CPU PM notifiers are run with RCU enabled/watching (see cpu_pm_notify() > and how it calls rcu_irq_enter_irqson() before calling the notifiers). Sure i will update in v2. > >> Remove this change since RCU will not be idle during CPU PM notifications >> hence not required to use _rcuidle tracepoint. Using _rcuidle tracepoint >> prevented rpmh driver to be loadable module as these are not exported >> symbols. >> >> This reverts commit efde2659b0fe835732047357b2902cca14f054d9. >> >> Cc: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> >> Cc: John Stultz <john.stultz@linaro.org> >> Cc: Stephen Rothwell <sfr@canb.auug.org.au> >> Signed-off-by: Maulik Shah <mkshah@codeaurora.org> >> --- > Otherwise > > Reviewed-by: Stephen Boyd <swboyd@chromium.org> Thanks for the review. Thanks, Maulik
On Wed, 19 Aug 2020 at 12:08, Maulik Shah <mkshah@codeaurora.org> wrote: > > This change was done based on an test results of unmerged series of > adding RSC power domain and using .power_off callback of genpd to > invoke rpmh_flush(). > > Call trace: > dump_backtrace+0x0/0x174 > show_stack+0x20/0x2c > dump_stack+0xc8/0x124 > lockdep_rcu_suspicious+0xe4/0x104 > __tcs_buffer_write+0x230/0x2d0 > rpmh_rsc_write_ctrl_data+0x210/0x270 > rpmh_flush+0x84/0x24c > rpmh_domain_power_off+0x78/0x98 > _genpd_power_off+0x40/0xc0 > genpd_power_off+0x168/0x208 > > Later the final merged solution is to use CPU PM notification to invoke > rpmh_flush() and .power_off callback of genpd is not implemented in the > driver. > > Remove this change since RCU will not be idle during CPU PM notifications > hence not required to use _rcuidle tracepoint. Using _rcuidle tracepoint > prevented rpmh driver to be loadable module as these are not exported > symbols. > > This reverts commit efde2659b0fe835732047357b2902cca14f054d9. > > Cc: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> > Cc: John Stultz <john.stultz@linaro.org> > Cc: Stephen Rothwell <sfr@canb.auug.org.au> > Signed-off-by: Maulik Shah <mkshah@codeaurora.org> Along with Stephen's comments, feel free to add: Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org> Also note, when using the PSCI OSI mode, I am proposing to use "genpd on/off notifiers" [1]. This may lead to similar RCU issues, but let's come back to adress that later on, when/if needed. Kind regards Uffe [1] https://www.spinics.net/lists/kernel/msg3629443.html > --- > drivers/soc/qcom/rpmh-rsc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c > index ae66757..fabe390d 100644 > --- a/drivers/soc/qcom/rpmh-rsc.c > +++ b/drivers/soc/qcom/rpmh-rsc.c > @@ -495,7 +495,7 @@ static void __tcs_buffer_write(struct rsc_drv *drv, int tcs_id, int cmd_id, > write_tcs_cmd(drv, RSC_DRV_CMD_MSGID, tcs_id, j, msgid); > write_tcs_cmd(drv, RSC_DRV_CMD_ADDR, tcs_id, j, cmd->addr); > write_tcs_cmd(drv, RSC_DRV_CMD_DATA, tcs_id, j, cmd->data); > - trace_rpmh_send_msg_rcuidle(drv, tcs_id, j, msgid, cmd); > + trace_rpmh_send_msg(drv, tcs_id, j, msgid, cmd); > } > > write_tcs_reg(drv, RSC_DRV_CMD_WAIT_FOR_CMPL, tcs_id, cmd_complete); > -- > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member > of Code Aurora Forum, hosted by The Linux Foundation >
diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c index ae66757..fabe390d 100644 --- a/drivers/soc/qcom/rpmh-rsc.c +++ b/drivers/soc/qcom/rpmh-rsc.c @@ -495,7 +495,7 @@ static void __tcs_buffer_write(struct rsc_drv *drv, int tcs_id, int cmd_id, write_tcs_cmd(drv, RSC_DRV_CMD_MSGID, tcs_id, j, msgid); write_tcs_cmd(drv, RSC_DRV_CMD_ADDR, tcs_id, j, cmd->addr); write_tcs_cmd(drv, RSC_DRV_CMD_DATA, tcs_id, j, cmd->data); - trace_rpmh_send_msg_rcuidle(drv, tcs_id, j, msgid, cmd); + trace_rpmh_send_msg(drv, tcs_id, j, msgid, cmd); } write_tcs_reg(drv, RSC_DRV_CMD_WAIT_FOR_CMPL, tcs_id, cmd_complete);
This change was done based on an test results of unmerged series of adding RSC power domain and using .power_off callback of genpd to invoke rpmh_flush(). Call trace: dump_backtrace+0x0/0x174 show_stack+0x20/0x2c dump_stack+0xc8/0x124 lockdep_rcu_suspicious+0xe4/0x104 __tcs_buffer_write+0x230/0x2d0 rpmh_rsc_write_ctrl_data+0x210/0x270 rpmh_flush+0x84/0x24c rpmh_domain_power_off+0x78/0x98 _genpd_power_off+0x40/0xc0 genpd_power_off+0x168/0x208 Later the final merged solution is to use CPU PM notification to invoke rpmh_flush() and .power_off callback of genpd is not implemented in the driver. Remove this change since RCU will not be idle during CPU PM notifications hence not required to use _rcuidle tracepoint. Using _rcuidle tracepoint prevented rpmh driver to be loadable module as these are not exported symbols. This reverts commit efde2659b0fe835732047357b2902cca14f054d9. Cc: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Maulik Shah <mkshah@codeaurora.org> --- drivers/soc/qcom/rpmh-rsc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)