Messages in this thread Patch in this message | | | From | Cristian Marussi <> | Subject | [RFC PATCH 03/10] firmware: arm_scmi: Add configurable polling mode for transports | Date | Sun, 6 Jun 2021 23:12:25 +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 8685619d38f9..8f4e6ebfc0ef 100644 --- a/drivers/firmware/arm_scmi/common.h +++ b/drivers/firmware/arm_scmi/common.h @@ -272,11 +272,18 @@ 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; }; @@ -322,12 +329,15 @@ struct scmi_device *scmi_child_dev_find(struct device *parent, * @max_msg: Maximum number of messages that can be pending * simultaneously in the system * @max_msg_size: Maximum size of data per message that can be handled. + * @force_polling: Flag to force this whole transport to use SCMI core polling + * mechanism instead of completion interrupts even if available. */ struct scmi_desc { const struct scmi_transport_ops *ops; int max_rx_timeout_ms; int max_msg; int max_msg_size; + bool force_polling; }; extern const struct scmi_desc scmi_mailbox_desc; diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index 759ae4a23e74..c11ff49f6b62 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -319,6 +319,15 @@ static void scmi_handle_response(struct scmi_chan_info *cinfo, } xfer = &minfo->xfer_block[xfer_id]; + + /* Discard unexpected messages when polling is active. */ + if (msg_type != MSG_TYPE_DELAYED_RESP && xfer->hdr.poll_completion) { + WARN_ON_ONCE(1); + dev_dbg(dev, + "Completion IRQ received but using polling. Ignore.\n"); + return; + } + /* * Even if a response was indeed expected on this slot at this point, * a buggy platform could wrongly reply feeding us an unexpected @@ -443,6 +452,9 @@ 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); @@ -1102,6 +1114,11 @@ 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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