[PATCH v6 4/5] PCI: mediatek-gen3: Move reset delay in mtk_pcie_en7581_power_up()

[Lorenzo Bianconi]

Airoha EN7581 has a hw bug asserting/releasing PCIE_PE_RSTB signal
causing occasional PCIe link down issues. In order to overcome the
problem, PCIe block is reset using REG_PCI_CONTROL (0x88) and
REG_RESET_CONTROL (0x834) registers available in the clock module
running clk_bulk_prepare_enable() in mtk_pcie_en7581_power_up().
In order to make the code more readable, move the wait for the time
needed to complete the PCIe reset from en7581_pci_enable() to
mtk_pcie_en7581_power_up().
Reduce reset timeout from 250ms to the standard PCIE_T_PVPERL_MS value
(100ms) since it has no impact on the driver behavior.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>
Acked-by: Stephen Boyd <sboyd at kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam at linaro.org>
Signed-off-by: Lorenzo Bianconi <lorenzo at kernel.org>
---
 drivers/clk/clk-en7523.c                    | 1 -
 drivers/pci/controller/pcie-mediatek-gen3.c | 7 +++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk-en7523.c b/drivers/clk/clk-en7523.c
index e52c5460e927f54c6df152c60560f438f89ec928..513730e5b953f4412b6b12b98c742692de5424c1 100644
--- a/drivers/clk/clk-en7523.c
+++ b/drivers/clk/clk-en7523.c
@@ -477,7 +477,6 @@ static int en7581_pci_enable(struct clk_hw *hw)
 	       REG_PCI_CONTROL_PERSTOUT;
 	val = readl(np_base + REG_PCI_CONTROL);
 	writel(val | mask, np_base + REG_PCI_CONTROL);
-	msleep(250);
 
 	return 0;
 }
diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
index 71df8817c1635b04b67233fb43abe2de7770b0f2..01e0b53cc1f22fc4b9270a2eb6a55e8948ba2f8b 100644
--- a/drivers/pci/controller/pcie-mediatek-gen3.c
+++ b/drivers/pci/controller/pcie-mediatek-gen3.c
@@ -974,6 +974,13 @@ static int mtk_pcie_en7581_power_up(struct mtk_gen3_pcie *pcie)
 		goto err_clk_prepare_enable;
 	}
 
+	/*
+	 * Airoha EN7581 performs PCIe reset via clk callbacks since it has a
+	 * hw issue with PCIE_PE_RSTB signal. Add wait for the time needed to
+	 * complete the PCIe reset.
+	 */
+	msleep(PCIE_T_PVPERL_MS);
+
 	return 0;
 
 err_clk_prepare_enable:

-- 
2.47.1