linux-kernel - [PATCH 1/4] remoteproc: k3-r5: Fix IPC-only mode detection

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Date: Fri, 21 Jun 2024 17:00:55 +0200
From: Richard Genoud <richard.genoud@...tlin.com>
To: Bjorn Andersson <andersson@...nel.org>,
	Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Philipp Zabel <p.zabel@...gutronix.de>,
	Suman Anna <s-anna@...com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Udit Kumar <u-kumar1@...com>,
	Thomas Richard <thomas.richard@...tlin.com>,
	Gregory CLEMENT <gregory.clement@...tlin.com>,
	Hari Nagalla <hnagalla@...com>,
	Théo Lebrun <theo.lebrun@...tlin.com>,
	linux-remoteproc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Richard Genoud <richard.genoud@...tlin.com>
Subject: [PATCH 1/4] remoteproc: k3-r5: Fix IPC-only mode detection

ret variable was used to test reset status, get from
reset_control_status() call. But this variable was overwritten by
ti_sci_proc_get_status() a few lines bellow.
And as ti_sci_proc_get_status() returns 0 or a negative value (in this
latter case, followed by a return), the expression !ret was always true,

Clearly, this was not what was intended:
In the comment above it's said that "requires both local and module
resets to be deasserted"; if reset_control_status() returns 0 it means
that the reset line is deasserted.
So, it's pretty clear that the return value of reset_control_status()
was intended to be used instead of ti_sci_proc_get_status() return
value.

This could lead in an incorrect IPC-only mode detection if reset line is
asserted (so reset_control_status() return > 0) and c_state != 0 and
halted == 0.
In this case, the old code would have detected an IPC-only mode instead
of a mismatched mode.

Fixes: 1168af40b1ad ("remoteproc: k3-r5: Add support for IPC-only mode for all R5Fs")
Signed-off-by: Richard Genoud <richard.genoud@...tlin.com>
---
 drivers/remoteproc/ti_k3_r5_remoteproc.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
index 50e486bcfa10..39a47540c590 100644
--- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
+++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
@@ -1144,6 +1144,7 @@ static int k3_r5_rproc_configure_mode(struct k3_r5_rproc *kproc)
 	u32 atcm_enable, btcm_enable, loczrama;
 	struct k3_r5_core *core0;
 	enum cluster_mode mode = cluster->mode;
+	int reset_ctrl_status;
 	int ret;
 
 	core0 = list_first_entry(&cluster->cores, struct k3_r5_core, elem);
@@ -1160,11 +1161,11 @@ static int k3_r5_rproc_configure_mode(struct k3_r5_rproc *kproc)
 			 r_state, c_state);
 	}
 
-	ret = reset_control_status(core->reset);
-	if (ret < 0) {
+	reset_ctrl_status = reset_control_status(core->reset);
+	if (reset_ctrl_status < 0) {
 		dev_err(cdev, "failed to get initial local reset status, ret = %d\n",
-			ret);
-		return ret;
+			reset_ctrl_status);
+		return reset_ctrl_status;
 	}
 
 	/*
@@ -1199,7 +1200,7 @@ static int k3_r5_rproc_configure_mode(struct k3_r5_rproc *kproc)
 	 * irrelevant if module reset is asserted (POR value has local reset
 	 * deasserted), and is deemed as remoteproc mode
 	 */
-	if (c_state && !ret && !halted) {
+	if (c_state && !reset_ctrl_status && !halted) {
 		dev_info(cdev, "configured R5F for IPC-only mode\n");
 		kproc->rproc->state = RPROC_DETACHED;
 		ret = 1;
@@ -1217,7 +1218,7 @@ static int k3_r5_rproc_configure_mode(struct k3_r5_rproc *kproc)
 		ret = 0;
 	} else {
 		dev_err(cdev, "mismatched mode: local_reset = %s, module_reset = %s, core_state = %s\n",
-			!ret ? "deasserted" : "asserted",
+			!reset_ctrl_status ? "deasserted" : "asserted",
 			c_state ? "deasserted" : "asserted",
 			halted ? "halted" : "unhalted");
 		ret = -EINVAL;