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charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 >> --- >> 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. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel