[PATCHv2 3/3] EDAC/fsl_ddr: restore MC error registers on probe failure

[Rosen Penev <rosenp@gmail.com>]

fsl_mc_err_probe() clears FSL_MC_ERR_DISABLE and, in EDAC_OPSTATE_INT
mode, sets FSL_MC_ERR_INT_EN to enable error reporting. If a later
initialization step fails and jumps to the err/err2 labels, the cleanup
only frees driver memory and does not restore these hardware registers.

This leaves the memory controller configured to generate interrupts while
no handler is successfully registered, which can cause an unhandled
interrupt storm on the shared IRQ line. Restore FSL_MC_ERR_DISABLE,
FSL_MC_ERR_INT_EN and the SBE threshold in both error paths.

Do not pre-initialize orig_ddr_err_disable/orig_ddr_err_sbe to 0; the
err path must only restore registers that were actually modified.
Split the error labels so early failures (before the first hardware
write at line ~~580) jump to err_free, which does cleanup without
touching hardware registers. Save orig_ddr_err_sbe alongside
orig_ddr_err_disable so the err label correctly restores both
registers, avoiding stale bootloader state clobbers.

Built for arm64 (defconfig + CONFIG_EDAC_FSL_DDR) with LLVM=1;
drivers/edac/fsl_ddr_edac.o compiles cleanly.

Fixes: ea2eb9a8b620 ("EDAC, fsl-ddr: Separate FSL DDR driver from MPC85xx")
Assisted-by: opencode:hy3-free
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/edac/fsl_ddr_edac.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/edac/fsl_ddr_edac.c b/drivers/edac/fsl_ddr_edac.c
index c505fb268474..139277c4e2f0 100644
--- a/drivers/edac/fsl_ddr_edac.c
+++ b/drivers/edac/fsl_ddr_edac.c
@@ -577,23 +577,22 @@ int fsl_mc_err_probe(struct platform_device *op)
 	pdata->orig_ddr_err_disable = ddr_in32(pdata, FSL_MC_ERR_DISABLE);
 	ddr_out32(pdata, FSL_MC_ERR_DISABLE, 0);
 
+	/* store the original SBE threshold */
+	pdata->orig_ddr_err_sbe = ddr_in32(pdata, FSL_MC_ERR_SBE) & 0xff0000;
+
 	/* clear all error bits */
 	ddr_out32(pdata, FSL_MC_ERR_DETECT, ~0);
 
 	res = edac_mc_add_mc_with_groups(mci, fsl_ddr_dev_groups);
 	if (res) {
 		edac_dbg(3, "failed edac_mc_add_mc()\n");
-		goto err;
+		goto err1;
 	}
 
 	if (edac_op_state == EDAC_OPSTATE_INT) {
 		ddr_out32(pdata, FSL_MC_ERR_INT_EN,
 			  DDR_EIE_MBEE | DDR_EIE_SBEE);
 
-		/* store the original error management threshold */
-		pdata->orig_ddr_err_sbe = ddr_in32(pdata,
-						   FSL_MC_ERR_SBE) & 0xff0000;
-
 		/* set threshold to 1 error per interrupt */
 		ddr_out32(pdata, FSL_MC_ERR_SBE, 0x10000);
 
@@ -621,6 +620,11 @@ int fsl_mc_err_probe(struct platform_device *op)
 
 err2:
 	edac_mc_del_mc(&op->dev);
+	ddr_out32(pdata, FSL_MC_ERR_INT_EN, 0);
+err1:
+	ddr_out32(pdata, FSL_MC_ERR_DISABLE,
+		  pdata->orig_ddr_err_disable);
+	ddr_out32(pdata, FSL_MC_ERR_SBE, pdata->orig_ddr_err_sbe);
 err:
 	edac_mc_free(mci);
 	return res;
-- 
2.55.0