netdev - [PATCH] net: stmmac: dwmac-qcom-ethqos: Enable RGMII functional clock on resume

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Date:   Tue, 22 Mar 2022 20:32:55 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Vinod Koul <vkoul@...nel.org>,
        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>,
        Paolo Abeni <pabeni@...hat.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>
Cc:     netdev@...r.kernel.org, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bhupesh Sharma <bhupesh.sharma@...aro.org>
Subject: [PATCH] net: stmmac: dwmac-qcom-ethqos: Enable RGMII functional clock on resume

When the Qualcomm ethqos driver is properly described in its associated
GDSC power-domain, the hardware will be powered down and loose its state
between qcom_ethqos_probe() and stmmac_init_dma_engine().

The result of this is that the functional clock from the RGMII IO macro
is no longer provides and the DMA software reset in dwmac4_dma_reset()
will time out, due to lacking clock signal.

Re-enable the functional clock, as part of the Qualcomm specific clock
enablement sequence to avoid this problem.

The final clock configuration will be adjusted by ethqos_fix_mac_speed()
once the link is being brought up.

Fixes: a7c30e62d4b8 ("net: stmmac: Add driver for Qualcomm ethqos")
Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
index 0cc28c79cc61..835caa15d55f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
@@ -487,6 +487,13 @@ static int ethqos_clks_config(void *priv, bool enabled)
 			dev_err(&ethqos->pdev->dev, "rgmii_clk enable failed\n");
 			return ret;
 		}
+
+		/* Enable functional clock to prevent DMA reset to timeout due
+		 * to lacking PHY clock after the hardware block has been power
+		 * cycled. The actual configuration will be adjusted once
+		 * ethqos_fix_mac_speed() is invoked.
+		 */
+		ethqos_set_func_clk_en(ethqos);
 	} else {
 		clk_disable_unprepare(ethqos->rgmii_clk);
 	}
-- 
2.33.1