[PATCH 1/3] net: stmmac: explicitly deassert GMAC_AHB_RESET

[Matthew Hagan]

We are currently assuming that GMAC_AHB_RESET will already be deasserted
by the bootloader. However if this has not been done, probing of the GMAC
will fail. To remedy this we must ensure GMAC_AHB_RESET has been deasserted
prior to probing.

Signed-off-by: Matthew Hagan <mnhagan88@xxxxxxxxx>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c     | 7 +++++++
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 7 +++++++
 include/linux/stmmac.h                                | 1 +
 3 files changed, 15 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 6d41dd6f9f7a..1e28058b65a8 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -6840,6 +6840,13 @@ int stmmac_dvr_probe(struct device *device,
 			reset_control_reset(priv->plat->stmmac_rst);
 	}
 
+	if (priv->plat->stmmac_ahb_rst) {
+		ret = reset_control_deassert(priv->plat->stmmac_ahb_rst);
+		if (ret == -ENOTSUPP)
+			dev_err(priv->device,
+				"unable to bring out of ahb reset\n");
+	}
+
 	/* Init MAC and get the capabilities */
 	ret = stmmac_hw_init(priv);
 	if (ret)
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 97a1fedcc9ac..d8ae58bdbbe3 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -600,6 +600,13 @@ stmmac_probe_config_dt(struct platform_device *pdev, u8 *mac)
 		goto error_hw_init;
 	}
 
+	plat->stmmac_ahb_rst = devm_reset_control_get_optional_shared(
+							&pdev->dev, "ahb");
+	if (IS_ERR(plat->stmmac_ahb_rst)) {
+		ret = plat->stmmac_ahb_rst;
+		goto error_hw_init;
+	}
+
 	return plat;
 
 error_hw_init:
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index e55a4807e3ea..9b6a64f3e3dc 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -239,6 +239,7 @@ struct plat_stmmacenet_data {
 	unsigned int mult_fact_100ns;
 	s32 ptp_max_adj;
 	struct reset_control *stmmac_rst;
+	struct reset_control *stmmac_ahb_rst;
 	struct stmmac_axi *axi;
 	int has_gmac4;
 	bool has_sun8i;
-- 
2.26.3