[PATCH v5 1/6] ata: ahci_st: Do not ignore errors when getting the reset controls

[Niklas Cassel]

st_ahci_probe_resets() treats any error from devm_reset_control_get() as
"reset control not defined" and continues with a NULL reset control:

	drv_data->pwr = devm_reset_control_get(dev, "pwr-dwn");
	if (IS_ERR(drv_data->pwr)) {
		dev_info(dev, "power reset control not defined\n");
		drv_data->pwr = NULL;
	}

This also swallows -EPROBE_DEFER, which is returned when the reset
controller providing the reset has not been probed yet. probe() then
continues as if the device tree did not specify any reset, so the resets
of the SATA IP are never deasserted, and st_ahci_configure_oob() and
ahci_platform_init_host() access the MMIO of an IP which is still held in
reset and powered down, which can result in an external abort.

The resets are optional in the binding, as they are not part of its
required properties, so use devm_reset_control_get_optional(), which
returns NULL if the reset is not specified in the device tree, and
propagate all other errors.

Note that an absent reset is now indicated by a NULL reset control
instead of an error, so the "reset control not defined" messages are
dropped.

Fixes: 76884cb2f7da ("ahci: st: Add support for ST's SATA IP")
Cc: stable at vger.kernel.org
Signed-off-by: Niklas Cassel <cassel at kernel.org>
---
 drivers/ata/ahci_st.c | 31 ++++++++++++++-----------------
 1 file changed, 14 insertions(+), 17 deletions(-)

diff --git a/drivers/ata/ahci_st.c b/drivers/ata/ahci_st.c
index 4336c8a6e208..819269a022ef 100644
--- a/drivers/ata/ahci_st.c
+++ b/drivers/ata/ahci_st.c
@@ -104,23 +104,20 @@ static int st_ahci_probe_resets(struct ahci_host_priv *hpriv,
 {
 	struct st_ahci_drv_data *drv_data = hpriv->plat_data;
 
-	drv_data->pwr = devm_reset_control_get(dev, "pwr-dwn");
-	if (IS_ERR(drv_data->pwr)) {
-		dev_info(dev, "power reset control not defined\n");
-		drv_data->pwr = NULL;
-	}
-
-	drv_data->sw_rst = devm_reset_control_get(dev, "sw-rst");
-	if (IS_ERR(drv_data->sw_rst)) {
-		dev_info(dev, "soft reset control not defined\n");
-		drv_data->sw_rst = NULL;
-	}
-
-	drv_data->pwr_rst = devm_reset_control_get(dev, "pwr-rst");
-	if (IS_ERR(drv_data->pwr_rst)) {
-		dev_dbg(dev, "power soft reset control not defined\n");
-		drv_data->pwr_rst = NULL;
-	}
+	drv_data->pwr = devm_reset_control_get_optional(dev, "pwr-dwn");
+	if (IS_ERR(drv_data->pwr))
+		return dev_err_probe(dev, PTR_ERR(drv_data->pwr),
+				     "failed to get pwr-dwn reset\n");
+
+	drv_data->sw_rst = devm_reset_control_get_optional(dev, "sw-rst");
+	if (IS_ERR(drv_data->sw_rst))
+		return dev_err_probe(dev, PTR_ERR(drv_data->sw_rst),
+				     "failed to get sw-rst reset\n");
+
+	drv_data->pwr_rst = devm_reset_control_get_optional(dev, "pwr-rst");
+	if (IS_ERR(drv_data->pwr_rst))
+		return dev_err_probe(dev, PTR_ERR(drv_data->pwr_rst),
+				     "failed to get pwr-rst reset\n");
 
 	return st_ahci_deassert_resets(hpriv, dev);
 }
-- 
2.55.0