[PATCH v2] PCI: imx6: Move clock enable after core reset assertion

[hongxing.zhu at oss.nxp.com]

From: Richard Zhu <hongxing.zhu at nxp.com>

Commit 610fa91d9863 ("PCI: imx6: Assert PERST# before enabling regulators")
inadvertently moved clock enablement before core reset assertion, breaking
PCI device initialization on i.MX6Q Apalis platforms with
ASM1061/ASM1062 SATA controllers connected.

NOTE: It is not 100% clear if the issue is specific to the ASM1061/ASM1062
device or on the specific power-up sequence (reset vs cold-power-on).

Logs:
root at apalis-imx6-11486042:~# dmesg | grep pcie
imx6q-pcie 1ffc000.pcie: host bridge /soc/pcie at 1ffc000 ranges:
imx6q-pcie 1ffc000.pcie:       IO 0x0001f80000..0x0001f8ffff -> 0x0000000000
imx6q-pcie 1ffc000.pcie:      MEM 0x0001000000..0x0001efffff -> 0x0001000000
imx6q-pcie 1ffc000.pcie: config reg[1] 0x01f00000 == cpu 0x01f00000
imx6q-pcie 1ffc000.pcie: iATU: unroll F, 4 ob, 4 ib, align 64K, limit 4G
imx6q-pcie 1ffc000.pcie: Link: Only Gen1 is enabled
imx6q-pcie 1ffc000.pcie: Link failed to come up. LTSSM: POLL_CONFIG
imx6q-pcie 1ffc000.pcie: probe with driver imx6q-pcie failed with error -110

To fix this regression, restore the original sequence where clocks are
enabled after asserting core reset and configuring the controller type.

Fixes: 610fa91d9863 ("PCI: imx6: Assert PERST# before enabling regulators")
Signed-off-by: Richard Zhu <hongxing.zhu at nxp.com>
Reported-by: Leonardo Costa <leoreis.costa at gmail.com>
Closes: https://lore.kernel.org/all/bl7i3obu2clzsgeoct2a4mtfhv6typcjdqmgneropf3hpgwve6@n2m5uhlduw57/T/#u
Reported-by: Franz Schnyder <fra.schnyder at gmail.com>
Closes: https://lore.kernel.org/all/t65y5d54axtksbfs7r4olcefqhwm6m4dz3njgnrnf7fcotj74i@o7avoznlafbj/
Cc: stable at vger.kernel.org # 7.2+
---
Changes in v2:
Update the commit message refer to Francesco' suggestions.
---
 drivers/pci/controller/dwc/pci-imx6.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 39790e66b98dc..f7a2eb257c169 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -1394,12 +1394,6 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
 		}
 	}
 
-	ret = imx_pcie_clk_enable(imx_pcie);
-	if (ret) {
-		dev_err(dev, "unable to enable pcie clocks: %d\n", ret);
-		goto err_pwrctrl_power_off;
-	}
-
 	if (pp->bridge && imx_check_flag(imx_pcie, IMX_PCIE_FLAG_HAS_LUT)) {
 		pp->bridge->enable_device = imx_pcie_enable_device;
 		pp->bridge->disable_device = imx_pcie_disable_device;
@@ -1415,6 +1409,12 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
 
 	imx_pcie_configure_type(imx_pcie);
 
+	ret = imx_pcie_clk_enable(imx_pcie);
+	if (ret) {
+		dev_err(dev, "unable to enable pcie clocks: %d\n", ret);
+		goto err_pwrctrl_power_off;
+	}
+
 	if (imx_pcie->phy) {
 		ret = phy_init(imx_pcie->phy);
 		if (ret) {

base-commit: 28d012efb4327f9c75d5e042a7c91e9a542efa98
-- 
2.34.1