linux-kernel - [PATCH v3] net: stmmac: explicitly deassert GMAC_AHB

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Date:   Tue,  8 Jun 2021 19:59:06 +0100
From:   Matthew Hagan <mnhagan88@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Matthew Hagan <mnhagan88@...il.com>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Voon Weifeng <weifeng.voon@...el.com>,
        Ong Boon Leong <boon.leong.ong@...el.com>,
        Wong Vee Khee <vee.khee.wong@...ux.intel.com>,
        Tan Tee Min <tee.min.tan@...el.com>,
        "Wong, Vee Khee" <vee.khee.wong@...el.com>,
        Michael Sit Wei Hong <michael.wei.hong.sit@...el.com>,
        netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3] net: stmmac: explicitly deassert GMAC_AHB_RESET

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.

v2 changes:
 - remove NULL condition check for stmmac_ahb_rst in stmmac_main.c
 - unwrap dev_err() message in stmmac_main.c
 - add PTR_ERR() around plat->stmmac_ahb_rst in stmmac_platform.c

v3 changes:
 - add error pointer to dev_err() output
 - add reset_control_assert(stmmac_ahb_rst) in stmmac_dvr_remove
 - revert PTR_ERR() around plat->stmmac_ahb_rst since this is performed
   on the returned value of ret by the calling function

Signed-off-by: Matthew Hagan <mnhagan88@...il.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c     | 6 ++++++
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 7 +++++++
 include/linux/stmmac.h                                | 1 +
 3 files changed, 14 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 6d41dd6f9f7a..78dafde70671 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -6840,6 +6840,11 @@ int stmmac_dvr_probe(struct device *device,
 			reset_control_reset(priv->plat->stmmac_rst);
 	}
 
+	ret = reset_control_deassert(priv->plat->stmmac_ahb_rst);
+	if (ret == -ENOTSUPP)
+		dev_err(priv->device, "unable to bring out of ahb reset: %pe\n",
+			ERR_PTR(ret));
+
 	/* Init MAC and get the capabilities */
 	ret = stmmac_hw_init(priv);
 	if (ret)
@@ -7072,6 +7077,7 @@ int stmmac_dvr_remove(struct device *dev)
 	phylink_destroy(priv->phylink);
 	if (priv->plat->stmmac_rst)
 		reset_control_assert(priv->plat->stmmac_rst);
+	reset_control_assert(priv->plat->stmmac_ahb_rst);
 	pm_runtime_put(dev);
 	pm_runtime_disable(dev);
 	if (priv->hw->pcs != STMMAC_PCS_TBI &&
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