| Message ID | 20230911194359.27547-2-quic_nkela@quicinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | Add qcom hvc/shmem transport support | expand |
On Mon, Sep 11, 2023 at 12:43:56PM -0700, Nikunj Kela wrote: > Currently, the return from the smc call assumes the completion of > the scmi request. However this may not be true in virtual platforms > that are using hvc doorbell. > > This change adds a Kconfig to enable the polling for the request > completion. > > Signed-off-by: Nikunj Kela <quic_nkela@quicinc.com> > --- > drivers/firmware/arm_scmi/Kconfig | 14 ++++++++++++++ > drivers/firmware/arm_scmi/smc.c | 15 ++++++++++++++- > 2 files changed, 28 insertions(+), 1 deletion(-) > > diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig > index ea0f5083ac47..771d60f8319f 100644 > --- a/drivers/firmware/arm_scmi/Kconfig > +++ b/drivers/firmware/arm_scmi/Kconfig > @@ -125,6 +125,20 @@ config ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE > in atomic context too, at the price of using a number of busy-waiting > primitives all over instead. If unsure say N. > > +config ARM_SCMI_TRANSPORT_SMC_POLL_COMPLETION > + bool "Enable polling support for SCMI SMC transport" > + depends on ARM_SCMI_TRANSPORT_SMC > + help > + Enable completion polling support for SCMI SMC based transport. > + > + If you want the SCMI SMC based transport to poll for the completion, > + answer Y. > + Enabling completion polling might be desired in the absence of the a2p > + irq when the return from smc/hvc call doesn't indicate the completion > + of the SCMI requests. This might be useful for instances used in > + virtual platforms. > + If unsure say N. > + > config ARM_SCMI_TRANSPORT_VIRTIO > bool "SCMI transport based on VirtIO" > depends on VIRTIO=y || VIRTIO=ARM_SCMI_PROTOCOL > diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c > index c193516a254d..0a0b7e401159 100644 > --- a/drivers/firmware/arm_scmi/smc.c > +++ b/drivers/firmware/arm_scmi/smc.c > @@ -250,6 +250,16 @@ static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret, > smc_channel_lock_release(scmi_info); > } > > +#ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC_POLL_COMPLETION > +static bool > +smc_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer) > +{ > + struct scmi_smc *scmi_info = cinfo->transport_info; > + > + return shmem_poll_done(scmi_info->shmem, xfer); > +} > +#endif > + > static const struct scmi_transport_ops scmi_smc_ops = { > .chan_available = smc_chan_available, > .chan_setup = smc_chan_setup, > @@ -257,6 +267,9 @@ static const struct scmi_transport_ops scmi_smc_ops = { > .send_message = smc_send_message, > .mark_txdone = smc_mark_txdone, > .fetch_response = smc_fetch_response, > +#ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC_POLL_COMPLETION > + .poll_done = smc_poll_done, > +#endif > }; > > const struct scmi_desc scmi_smc_desc = { > @@ -272,6 +285,6 @@ const struct scmi_desc scmi_smc_desc = { > * for the issued command will be immmediately ready to be fetched > * from the shared memory area. > */ > - .sync_cmds_completed_on_ret = true, > + .sync_cmds_completed_on_ret = !IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_POLL_COMPLETION), > .atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
On 10/2/2023 11:18 AM, Brian Masney wrote: > On Mon, Sep 11, 2023 at 12:43:56PM -0700, Nikunj Kela wrote: >> Currently, the return from the smc call assumes the completion of >> the scmi request. However this may not be true in virtual platforms >> that are using hvc doorbell. >> >> This change adds a Kconfig to enable the polling for the request >> completion. >> >> Signed-off-by: Nikunj Kela <quic_nkela@quicinc.com> >> --- >> drivers/firmware/arm_scmi/Kconfig | 14 ++++++++++++++ >> drivers/firmware/arm_scmi/smc.c | 15 ++++++++++++++- >> 2 files changed, 28 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig >> index ea0f5083ac47..771d60f8319f 100644 >> --- a/drivers/firmware/arm_scmi/Kconfig >> +++ b/drivers/firmware/arm_scmi/Kconfig >> @@ -125,6 +125,20 @@ config ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE >> in atomic context too, at the price of using a number of busy-waiting >> primitives all over instead. If unsure say N. >> >> +config ARM_SCMI_TRANSPORT_SMC_POLL_COMPLETION >> + bool "Enable polling support for SCMI SMC transport" >> + depends on ARM_SCMI_TRANSPORT_SMC >> + help >> + Enable completion polling support for SCMI SMC based transport. >> + >> + If you want the SCMI SMC based transport to poll for the completion, >> + answer Y. >> + Enabling completion polling might be desired in the absence of the a2p >> + irq when the return from smc/hvc call doesn't indicate the completion >> + of the SCMI requests. This might be useful for instances used in >> + virtual platforms. >> + If unsure say N. >> + >> config ARM_SCMI_TRANSPORT_VIRTIO >> bool "SCMI transport based on VirtIO" >> depends on VIRTIO=y || VIRTIO=ARM_SCMI_PROTOCOL >> diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c >> index c193516a254d..0a0b7e401159 100644 >> --- a/drivers/firmware/arm_scmi/smc.c >> +++ b/drivers/firmware/arm_scmi/smc.c >> @@ -250,6 +250,16 @@ static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret, >> smc_channel_lock_release(scmi_info); >> } >> >> +#ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC_POLL_COMPLETION >> +static bool >> +smc_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer) >> +{ >> + struct scmi_smc *scmi_info = cinfo->transport_info; >> + >> + return shmem_poll_done(scmi_info->shmem, xfer); >> +} >> +#endif >> + >> static const struct scmi_transport_ops scmi_smc_ops = { >> .chan_available = smc_chan_available, >> .chan_setup = smc_chan_setup, >> @@ -257,6 +267,9 @@ static const struct scmi_transport_ops scmi_smc_ops = { >> .send_message = smc_send_message, >> .mark_txdone = smc_mark_txdone, >> .fetch_response = smc_fetch_response, >> +#ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC_POLL_COMPLETION >> + .poll_done = smc_poll_done, >> +#endif >> }; >> >> const struct scmi_desc scmi_smc_desc = { >> @@ -272,6 +285,6 @@ const struct scmi_desc scmi_smc_desc = { >> * for the issued command will be immmediately ready to be fetched >> * from the shared memory area. >> */ >> - .sync_cmds_completed_on_ret = true, >> + .sync_cmds_completed_on_ret = !IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_POLL_COMPLETION), >> .atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE), > From a Linux distributor viewpoint, it would be nice if this was > determined at runtime, rather than at compile time. We generate a single > kernel binary that's used on systems from multiple hardware > manufacturers. We'd run into an issue if one company required this, but > another one didn't. We may potentially run into this same type of issue > with the upstream arm64 defconfig. > > Brian This is a transport dependent property. Either the transport supports "completion on return of the smc call" or not. For a given platform, this will be fixed for all channels. This is similar to CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE which is also a Kconfig.
On Mon, Sep 11, 2023 at 12:43:56PM -0700, Nikunj Kela wrote: > Currently, the return from the smc call assumes the completion of > the scmi request. However this may not be true in virtual platforms > that are using hvc doorbell. > Hmm, it is expectation from SMCCC for the fast calls. Is you HVC FID not a fast call. AFAIK, only TOS use yielding calls. Are you using them here ? If not, this must complete when the SMC/HVC returns. We added support for platforms indicating the same via interrupt. I would like to avoid adding this build config. Why does it require polling ? Broken firmware ? I would add a compatible for that. Or if the qcom always wants to do this way, just make it specific to the qcom compatible. I would avoid a config flag as it needs to be always enabled for single image and affects other platforms as well. So please drop this change. If this is absolutely needed, just add additional property which DT maintainers may not like as it is more like a policy or just make it compatible specific. -- Regards, Sudeep
On Tue, Oct 03, 2023 at 11:33:17AM +0100, Sudeep Holla wrote: > On Mon, Sep 11, 2023 at 12:43:56PM -0700, Nikunj Kela wrote: > > Currently, the return from the smc call assumes the completion of > > the scmi request. However this may not be true in virtual platforms > > that are using hvc doorbell. > > > > Hmm, it is expectation from SMCCC for the fast calls. Is you HVC FID > not a fast call. AFAIK, only TOS use yielding calls. Are you using them > here ? If not, this must complete when the SMC/HVC returns. We added > support for platforms indicating the same via interrupt. > > I would like to avoid adding this build config. Why does it require polling ? > Broken firmware ? I would add a compatible for that. Or if the qcom always > wants to do this way, just make it specific to the qcom compatible. > > I would avoid a config flag as it needs to be always enabled for single > image and affects other platforms as well. So please drop this change. > If this is absolutely needed, just add additional property which DT > maintainers may not like as it is more like a policy or just make it > compatible specific. > Not sure if it could be acceptable or controversial, BUT if there is the need somehow to support polling for yielding calls (depending on the location of the SCMI server), should not we think about doing this by just looking up dynamically the fast-call bits in the provided FID ? Why we need another binding, given that the FID is currently already statically provided by the DT itself (via smc-id) or dynamically by the hypervisor at setup by the changes in this series and the SMCCC spec clearly defines how the IDs are supposed to be formed for fast-atomic-calls ? This way we could enforce the compliance with the SMCCC spec tooo... ...for sure it would require a bit of work in the core, though, given the const nature of some of this structures. Thanks, Cristian
On 10/3/2023 3:33 AM, Sudeep Holla wrote: > On Mon, Sep 11, 2023 at 12:43:56PM -0700, Nikunj Kela wrote: >> Currently, the return from the smc call assumes the completion of >> the scmi request. However this may not be true in virtual platforms >> that are using hvc doorbell. >> > Hmm, it is expectation from SMCCC for the fast calls. Is you HVC FID > not a fast call. AFAIK, only TOS use yielding calls. Are you using them > here ? If not, this must complete when the SMC/HVC returns. We added > support for platforms indicating the same via interrupt. > > I would like to avoid adding this build config. Why does it require polling ? > Broken firmware ? I would add a compatible for that. Or if the qcom always > wants to do this way, just make it specific to the qcom compatible. > > I would avoid a config flag as it needs to be always enabled for single > image and affects other platforms as well. So please drop this change. > If this is absolutely needed, just add additional property which DT > maintainers may not like as it is more like a policy or just make it > compatible specific. > > -- > Regards, > Sudeep We are using Fast call FID. We are using completion IRQ for all the scmi instances except one where we need to communicate with the server when GIC is in suspended state in HLOS. We will need to poll the channel for completion in that use case. I am open to suggestions.
On Tue, Oct 03, 2023 at 08:53:20AM -0700, Nikunj Kela wrote: > > On 10/3/2023 3:33 AM, Sudeep Holla wrote: > > On Mon, Sep 11, 2023 at 12:43:56PM -0700, Nikunj Kela wrote: > > > Currently, the return from the smc call assumes the completion of > > > the scmi request. However this may not be true in virtual platforms > > > that are using hvc doorbell. > > > > > Hmm, it is expectation from SMCCC for the fast calls. Is you HVC FID > > not a fast call. AFAIK, only TOS use yielding calls. Are you using them > > here ? If not, this must complete when the SMC/HVC returns. We added > > support for platforms indicating the same via interrupt. > > > > I would like to avoid adding this build config. Why does it require polling ? > > Broken firmware ? I would add a compatible for that. Or if the qcom always > > wants to do this way, just make it specific to the qcom compatible. > > > > I would avoid a config flag as it needs to be always enabled for single > > image and affects other platforms as well. So please drop this change. > > If this is absolutely needed, just add additional property which DT > > maintainers may not like as it is more like a policy or just make it > > compatible specific. > > > > -- > > Regards, > > Sudeep > We are using Fast call FID. We are using completion IRQ for all the scmi > instances except one where we need to communicate with the server when GIC > is in suspended state in HLOS. We will need to poll the channel for > completion in that use case. I am open to suggestions. IIUC, for the sake of that one corner case, you have added the polling Kconfig and will be enabled for all the case and even on other platforms in a single Image. I think we could be something better, no ? Please share details on that one corner case. Is it in the scmi drivers already ? If so, specifics please. If no, again provide details on how you plan to use. We do have ways to make a polling call, but haven't mixed it with interrupt based calls for a reason, but we can revisit if it makes sense. -- Regards, Sudeep
On 10/4/2023 9:11 AM, Sudeep Holla wrote: > On Tue, Oct 03, 2023 at 08:53:20AM -0700, Nikunj Kela wrote: >> On 10/3/2023 3:33 AM, Sudeep Holla wrote: >>> On Mon, Sep 11, 2023 at 12:43:56PM -0700, Nikunj Kela wrote: >>>> Currently, the return from the smc call assumes the completion of >>>> the scmi request. However this may not be true in virtual platforms >>>> that are using hvc doorbell. >>>> >>> Hmm, it is expectation from SMCCC for the fast calls. Is you HVC FID >>> not a fast call. AFAIK, only TOS use yielding calls. Are you using them >>> here ? If not, this must complete when the SMC/HVC returns. We added >>> support for platforms indicating the same via interrupt. >>> >>> I would like to avoid adding this build config. Why does it require polling ? >>> Broken firmware ? I would add a compatible for that. Or if the qcom always >>> wants to do this way, just make it specific to the qcom compatible. >>> >>> I would avoid a config flag as it needs to be always enabled for single >>> image and affects other platforms as well. So please drop this change. >>> If this is absolutely needed, just add additional property which DT >>> maintainers may not like as it is more like a policy or just make it >>> compatible specific. >>> >>> -- >>> Regards, >>> Sudeep >> We are using Fast call FID. We are using completion IRQ for all the scmi >> instances except one where we need to communicate with the server when GIC >> is in suspended state in HLOS. We will need to poll the channel for >> completion in that use case. I am open to suggestions. > IIUC, for the sake of that one corner case, you have added the polling > Kconfig and will be enabled for all the case and even on other platforms > in a single Image. I think we could be something better, no ? > > Please share details on that one corner case. > Is it in the scmi drivers already ? If so, specifics please. > If no, again provide details on how you plan to use. We do have ways > to make a polling call, but haven't mixed it with interrupt based calls > for a reason, but we can revisit if it makes sense. > > -- > Regards, > Sudeep Ok. I will discard this patch for now from this series and will explore alternative ways instead of polling that might work in our usecase. If required, will provide you with more details in a separate patch. Thanks!
diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig index ea0f5083ac47..771d60f8319f 100644 --- a/drivers/firmware/arm_scmi/Kconfig +++ b/drivers/firmware/arm_scmi/Kconfig @@ -125,6 +125,20 @@ config ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE in atomic context too, at the price of using a number of busy-waiting primitives all over instead. If unsure say N. +config ARM_SCMI_TRANSPORT_SMC_POLL_COMPLETION + bool "Enable polling support for SCMI SMC transport" + depends on ARM_SCMI_TRANSPORT_SMC + help + Enable completion polling support for SCMI SMC based transport. + + If you want the SCMI SMC based transport to poll for the completion, + answer Y. + Enabling completion polling might be desired in the absence of the a2p + irq when the return from smc/hvc call doesn't indicate the completion + of the SCMI requests. This might be useful for instances used in + virtual platforms. + If unsure say N. + config ARM_SCMI_TRANSPORT_VIRTIO bool "SCMI transport based on VirtIO" depends on VIRTIO=y || VIRTIO=ARM_SCMI_PROTOCOL diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c index c193516a254d..0a0b7e401159 100644 --- a/drivers/firmware/arm_scmi/smc.c +++ b/drivers/firmware/arm_scmi/smc.c @@ -250,6 +250,16 @@ static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret, smc_channel_lock_release(scmi_info); } +#ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC_POLL_COMPLETION +static bool +smc_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer) +{ + struct scmi_smc *scmi_info = cinfo->transport_info; + + return shmem_poll_done(scmi_info->shmem, xfer); +} +#endif + static const struct scmi_transport_ops scmi_smc_ops = { .chan_available = smc_chan_available, .chan_setup = smc_chan_setup, @@ -257,6 +267,9 @@ static const struct scmi_transport_ops scmi_smc_ops = { .send_message = smc_send_message, .mark_txdone = smc_mark_txdone, .fetch_response = smc_fetch_response, +#ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC_POLL_COMPLETION + .poll_done = smc_poll_done, +#endif }; const struct scmi_desc scmi_smc_desc = { @@ -272,6 +285,6 @@ const struct scmi_desc scmi_smc_desc = { * for the issued command will be immmediately ready to be fetched * from the shared memory area. */ - .sync_cmds_completed_on_ret = true, + .sync_cmds_completed_on_ret = !IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_POLL_COMPLETION), .atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE), };
Currently, the return from the smc call assumes the completion of the scmi request. However this may not be true in virtual platforms that are using hvc doorbell. This change adds a Kconfig to enable the polling for the request completion. Signed-off-by: Nikunj Kela <quic_nkela@quicinc.com> --- drivers/firmware/arm_scmi/Kconfig | 14 ++++++++++++++ drivers/firmware/arm_scmi/smc.c | 15 ++++++++++++++- 2 files changed, 28 insertions(+), 1 deletion(-)