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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Fabio Estevam <festevam@gmail.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Rob Herring <robh@kernel.org>,
        Richard Zhu <hongxing.zhu@nxp.com>
Subject: [PATCH 5.16 0197/1017] PCI: imx6: Allow to probe when dw_pcie_wait_for_link() fails
Date:   Tue,  5 Apr 2022 09:18:30 +0200
Message-Id: <20220405070400.095326941@linuxfoundation.org>
In-Reply-To: <20220405070354.155796697@linuxfoundation.org>
References: <20220405070354.155796697@linuxfoundation.org>
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From: Fabio Estevam <festevam@gmail.com>

commit f81f095e87715e198471f4653952fe5e3f824874 upstream.

The intention of commit 886a9c134755 ("PCI: dwc: Move link handling into
common code") was to standardize the behavior of link down as explained
in its commit log:

"The behavior for a link down was inconsistent as some drivers would fail
probe in that case while others succeed. Let's standardize this to
succeed as there are usecases where devices (and the link) appear later
even without hotplug. For example, a reconfigured FPGA device."

The pci-imx6 still fails to probe when the link is not present, which
causes the following warning:

imx6q-pcie 8ffc000.pcie: Phy link never came up
imx6q-pcie: probe of 8ffc000.pcie failed with error -110
------------[ cut here ]------------
WARNING: CPU: 0 PID: 30 at drivers/regulator/core.c:2257 _regulator_put.part.0+0x1b8/0x1dc
Modules linked in:
CPU: 0 PID: 30 Comm: kworker/u2:2 Not tainted 5.15.0-next-20211103 #1
Hardware name: Freescale i.MX6 SoloX (Device Tree)
Workqueue: events_unbound async_run_entry_fn
[<c0111730>] (unwind_backtrace) from [<c010bb74>] (show_stack+0x10/0x14)
[<c010bb74>] (show_stack) from [<c0f90290>] (dump_stack_lvl+0x58/0x70)
[<c0f90290>] (dump_stack_lvl) from [<c012631c>] (__warn+0xd4/0x154)
[<c012631c>] (__warn) from [<c0f87b00>] (warn_slowpath_fmt+0x74/0xa8)
[<c0f87b00>] (warn_slowpath_fmt) from [<c076b4bc>] (_regulator_put.part.0+0x1b8/0x1dc)
[<c076b4bc>] (_regulator_put.part.0) from [<c076b574>] (regulator_put+0x2c/0x3c)
[<c076b574>] (regulator_put) from [<c08c3740>] (release_nodes+0x50/0x178)

Fix this problem by ignoring the dw_pcie_wait_for_link() error like
it is done on the other dwc drivers.

Tested on imx6sx-sdb and imx6q-sabresd boards.

Link: https://lore.kernel.org/r/20220106103645.2790803-1-festevam@gmail.com
Fixes: 886a9c134755 ("PCI: dwc: Move link handling into common code")
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Richard Zhu <hongxing.zhu@nxp.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/pci/controller/dwc/pci-imx6.c |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -779,9 +779,7 @@ static int imx6_pcie_start_link(struct d
 	/* Start LTSSM. */
 	imx6_pcie_ltssm_enable(dev);
 
-	ret = dw_pcie_wait_for_link(pci);
-	if (ret)
-		goto err_reset_phy;
+	dw_pcie_wait_for_link(pci);
 
 	if (pci->link_gen == 2) {
 		/* Allow Gen2 mode after the link is up. */
@@ -817,11 +815,7 @@ static int imx6_pcie_start_link(struct d
 		}
 
 		/* Make sure link training is finished as well! */
-		ret = dw_pcie_wait_for_link(pci);
-		if (ret) {
-			dev_err(dev, "Failed to bring link up!\n");
-			goto err_reset_phy;
-		}
+		dw_pcie_wait_for_link(pci);
 	} else {
 		dev_info(dev, "Link: Gen2 disabled\n");
 	}