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   1 From 90d4e466c9ea2010f33880a36317a8486ccbe082 Mon Sep 17 00:00:00 2001
   2 From: Lorenzo Bianconi <lorenzo@kernel.org>
   3 Date: Wed, 8 Jan 2025 10:50:43 +0100
   4 Subject: [PATCH 4/6] PCI: mediatek-gen3: Move reset delay in
   5  mtk_pcie_en7581_power_up()
   6 MIME-Version: 1.0
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   9
  10 Airoha EN7581 has a hw bug asserting/releasing PCIE_PE_RSTB signal
  11 causing occasional PCIe link down issues. In order to overcome the
  12 problem, PCIe block is reset using REG_PCI_CONTROL (0x88) and
  13 REG_RESET_CONTROL (0x834) registers available in the clock module
  14 running clk_bulk_prepare_enable() in mtk_pcie_en7581_power_up().
  15
  16 In order to make the code more readable, move the wait for the time
  17 needed to complete the PCIe reset from en7581_pci_enable() to
  18 mtk_pcie_en7581_power_up().
  19
  20 Reduce reset timeout from 250ms to the standard PCIE_T_PVPERL_MS value
  21 (100ms) since it has no impact on the driver behavior.
  22
  23 Link: https://lore.kernel.org/r/20250108-pcie-en7581-fixes-v6-4-21ac939a3b9b@kernel.org
  24 Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
  25 Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
  26 Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
  27 Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
  28 Acked-by: Stephen Boyd <sboyd@kernel.org>
  29 ---
  30  drivers/clk/clk-en7523.c                    | 1 -
  31  drivers/pci/controller/pcie-mediatek-gen3.c | 7 +++++++
  32  2 files changed, 7 insertions(+), 1 deletion(-)
  33
  34 --- a/drivers/clk/clk-en7523.c
  35 +++ b/drivers/clk/clk-en7523.c
  36 @@ -489,7 +489,6 @@ static int en7581_pci_enable(struct clk_
  37                REG_PCI_CONTROL_PERSTOUT;
  38         val = readl(np_base + REG_PCI_CONTROL);
  39         writel(val | mask, np_base + REG_PCI_CONTROL);
  40 -       msleep(250);
  41
  42         return 0;
  43  }
  44 --- a/drivers/pci/controller/pcie-mediatek-gen3.c
  45 +++ b/drivers/pci/controller/pcie-mediatek-gen3.c
  46 @@ -936,6 +936,13 @@ static int mtk_pcie_en7581_power_up(stru
  47                 goto err_clk_prepare_enable;
  48         }
  49
  50 +       /*
  51 +        * Airoha EN7581 performs PCIe reset via clk callbacks since it has a
  52 +        * hw issue with PCIE_PE_RSTB signal. Add wait for the time needed to
  53 +        * complete the PCIe reset.
  54 +        */
  55 +       msleep(PCIE_T_PVPERL_MS);
  56 +
  57         return 0;
  58
  59  err_clk_prepare_enable: