[PATCH 5.17 0799/1126] net: stmmac: dwmac-qcom-ethqos: Enable RGMII functional clock on resume

[Greg Kroah-Hartman]

From: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>

[ Upstream commit ffba2123e1714a27e9362fda57c42155dda37efc ]

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@xxxxxxxxxx>
Tested-and-reviewed-by: Bhupesh Sharma <bhupesh.sharma@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220323033255.2282930-1-bjorn.andersson@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 2ffa0a11eea5..569683f33804 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
@@ -460,6 +460,13 @@ 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);
 	}
-- 
2.34.1