@@ -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
@@ -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) {
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(+)