diff mbox series

[v2,7/7] soc: microchip: mpfs: handle timeouts and failed services differently

Message ID 20230120143734.3438755-8-conor.dooley@microchip.com (mailing list archive)
State Changes Requested
Delegated to: Conor Dooley
Headers show
Series MPFS system controller/mailbox fixes | expand

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Context Check Description
conchuod/cover_letter success Series has a cover letter
conchuod/tree_selection success Guessed tree name to be fixes
conchuod/fixes_present success Fixes tag present in non-next series
conchuod/maintainers_pattern success MAINTAINERS pattern errors before the patch: 13 and now 13
conchuod/verify_signedoff success Signed-off-by tag matches author and committer
conchuod/kdoc success Errors and warnings before: 0 this patch: 0
conchuod/module_param success Was 0 now: 0
conchuod/build_rv64_gcc_allmodconfig success Errors and warnings before: 0 this patch: 0
conchuod/alphanumeric_selects success Out of order selects before the patch: 57 and now 57
conchuod/build_rv32_defconfig success Build OK
conchuod/dtb_warn_rv64 success Errors and warnings before: 2 this patch: 2
conchuod/header_inline success No static functions without inline keyword in header files
conchuod/checkpatch success total: 0 errors, 0 warnings, 0 checks, 35 lines checked
conchuod/source_inline success Was 0 now: 0
conchuod/build_rv64_nommu_k210_defconfig success Build OK
conchuod/verify_fixes success No Fixes tag
conchuod/build_rv64_nommu_virt_defconfig success Build OK

Commit Message

Conor Dooley Jan. 20, 2023, 2:37 p.m. UTC
The system controller will only deliver an interrupt if a service
succeeds. This leaves us in the unfortunate position with current code
where there is no way to differentiate between a legitimate timeout
where the service has not completed & where it has completed, but
failed.

mbox_send_message() has its own completion, and it will time out of the
system controller does not lower the busy flag. In this case, a timeout
has occurred and the error can be propagated back to the caller.

If the busy flag is lowered, but no interrupt has arrived to trigger the
rx callback, the service can be deemed to have failed. Report EBADMSG in
this case so that callers can differentiate.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
 drivers/soc/microchip/mpfs-sys-controller.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/soc/microchip/mpfs-sys-controller.c b/drivers/soc/microchip/mpfs-sys-controller.c
index da9cfeda6f78..2dd100ab21b1 100644
--- a/drivers/soc/microchip/mpfs-sys-controller.c
+++ b/drivers/soc/microchip/mpfs-sys-controller.c
@@ -45,14 +45,25 @@  int mpfs_blocking_transaction(struct mpfs_sys_controller *sys_controller, struct
 	reinit_completion(&sys_controller->c);
 
 	ret = mbox_send_message(sys_controller->chan, msg);
-	if (ret < 0)
+	if (ret < 0) {
+		dev_warn(sys_controller->client.dev,
+			 "MPFS sys controller service timeout\n");
 		goto out;
+	}
 
 	ret = 0; /* mbox_send_message returns positive integers on success */
+
+	/*
+	 * Unfortunately, the system controller will only deliver an interrupt
+	 * if a service succeeds. mbox_send_message() will block until the busy
+	 * flag is gone. If the busy flag is gone but no interrupt has arrived
+	 * to trigger the rx callback then the service can be deemed to have
+	 * failed.
+	 */
 	if (!wait_for_completion_timeout(&sys_controller->c, timeout)) {
-		ret = -ETIMEDOUT;
+		ret = -EBADMSG;
 		dev_warn(sys_controller->client.dev,
-			 "MPFS sys controller transaction timeout\n");
+			 "MPFS sys controller service failed\n");
 	}
 
 out:
@@ -110,6 +121,7 @@  static int mpfs_sys_controller_probe(struct platform_device *pdev)
 	sys_controller->client.dev = dev;
 	sys_controller->client.rx_callback = rx_callback;
 	sys_controller->client.tx_block = 1U;
+	sys_controller->client.tx_tout = msecs_to_jiffies(MPFS_SYS_CTRL_TIMEOUT_MS);
 
 	sys_controller->chan = mbox_request_channel(&sys_controller->client, 0);
 	if (IS_ERR(sys_controller->chan)) {