Messages in this thread Patch in this message | | | From | Cristian Marussi <> | Subject | [RFC PATCH v2 1/8] firmware: arm_scmi: Add configurable polling mode for transports | Date | Mon, 5 Jul 2021 18:10:15 +0100 |
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SCMI communications along TX channels can optionally be provided of a completion interrupt; when such interrupt is not available, command transactions should rely on polling, where the SCMI core takes care to repeatedly evaluates the transport-specific .poll_done() function to determine if a request was completed or timed out.
Such mechanism is already present and working on a single transfer base: SCMI protocols can indeed enable hdr.poll_completion on specific commands ahead of each transfer and cause that transaction to be handled with polling.
Introduce a couple of flags to be able to enforce such polling behaviour globally at will:
- scmi_desc.force_polling: to statically switch the whole transport to polling mode.
- scmi_chan_info.needs_polling: to switch a single channel dynamically to polling mode if at runtime is determined that no completion interrupt was available for such channel.
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> --- drivers/firmware/arm_scmi/common.h | 10 ++++++++++ drivers/firmware/arm_scmi/driver.c | 17 +++++++++++++++++ 2 files changed, 27 insertions(+)
diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h index 61f1d7e1742b..eb45f2dced03 100644 --- a/drivers/firmware/arm_scmi/common.h +++ b/drivers/firmware/arm_scmi/common.h @@ -320,11 +320,18 @@ void scmi_protocol_release(const struct scmi_handle *handle, u8 protocol_id); * @dev: Reference to device in the SCMI hierarchy corresponding to this * channel * @handle: Pointer to SCMI entity handle + * @needs_polling: Flag to indicate that this channel has no completion + * interrupt mechanism, so it needs SCMI core to poll, using + * .poll_done(), to determine when a command has completed. + * This can be dynamically set by transports at run-time inside + * their provided .chan_setup() when they determine no + * completion interrupt is available. * @transport_info: Transport layer related information */ struct scmi_chan_info { struct device *dev; struct scmi_handle *handle; + bool needs_polling; void *transport_info; }; @@ -386,6 +393,8 @@ struct scmi_device *scmi_child_dev_find(struct device *parent, * @using_xfers_delegation: A flag to indicate if the described transport will * handle delegated xfers, so the core can derive * proper related assumptions. + * @force_polling: Flag to force this whole transport to use SCMI core polling + * mechanism instead of completion interrupts even if available. */ struct scmi_desc { int (*init)(void); @@ -395,6 +404,7 @@ struct scmi_desc { int max_msg; int max_msg_size; bool using_xfers_delegation; + bool force_polling; }; #ifdef CONFIG_ARM_SCMI_TRANSPORT_MAILBOX diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index 218901492229..d1814c58f4ba 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -816,6 +816,15 @@ static void scmi_handle_response(struct scmi_chan_info *cinfo, u32 msg_hdr) scmi_xfer_state_update(xfer); + /* Discard unexpected messages when polling is active. */ + if (xfer->hdr.type != MSG_TYPE_DELAYED_RESP && + xfer->hdr.poll_completion) { + WARN_ON_ONCE(1); + dev_dbg(cinfo->dev, + "Completion IRQ received but using polling. Ignore.\n"); + return; + } + /* rx.len could be shrunk in the sync do_xfer, so reset to maxsz */ if (xfer->hdr.type == MSG_TYPE_DELAYED_RESP) xfer->rx.len = info->desc->max_msg_size; @@ -929,6 +938,9 @@ static int do_xfer(const struct scmi_protocol_handle *ph, if (unlikely(!cinfo)) return -EINVAL; + if (info->desc->force_polling || cinfo->needs_polling) + xfer->hdr.poll_completion = true; + trace_scmi_xfer_begin(xfer->transfer_id, xfer->hdr.id, xfer->hdr.protocol_id, xfer->hdr.seq, xfer->hdr.poll_completion); @@ -1643,6 +1655,11 @@ static int scmi_chan_setup(struct scmi_info *info, struct device *dev, if (ret) return ret; + if (tx && (cinfo->needs_polling || info->desc->force_polling)) + dev_info(dev, + "Enabled polling mode for TX channel - prot_id:%d\n", + prot_id); + idr_alloc: ret = idr_alloc(idr, cinfo, prot_id, prot_id + 1, GFP_KERNEL); if (ret != prot_id) { -- 2.17.1
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