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kernel: backport pcie enumeration fix to kernel 4.9 

This issue is also present in kernel 4.9 starting from 4.9.71
Adapted the patch, as the fixed function is in another location here.

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
openwrt-18.06
Koen Vandeputte 2018-02-19 10:46:14 +01:00 committed by John Crispin
parent 138c76332b
commit 2f85985da2
1 changed files with 62 additions and 0 deletions
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62
target/linux/generic/pending-4.9/812-pci-dwc-fix-enumeration.patch Normal file
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@ -0,0 +1,62 @@
From patchwork Tue Jan 9 14:42:21 2018
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: PCI: dwc: fix enumeration end when reaching root subordinate
From: Koen Vandeputte <koen.vandeputte@ncentric.com>
X-Patchwork-Id: 10152443
Message-Id: <1515508941-20055-1-git-send-email-koen.vandeputte@ncentric.com>
To: linux-pci@vger.kernel.org
Cc: bhelgaas@google.com, lorenzo.pieralisi@arm.com,
Joao.Pinto@synopsys.com, jingoohan1@gmail.com, niklas.cassel@axis.com,
Koen Vandeputte <koen.vandeputte@ncentric.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>
Date: Tue, 9 Jan 2018 15:42:21 +0100
The subordinate value indicates the highest bus number which can be
reached downstream though a certain device.
Commit a20c7f36bd3d ("PCI: Do not allocate more buses than available in
parent")
ensures that downstream devices cannot assign busnumbers higher than the
upstream device subordinate number, which was indeed illogical.
By default, dw_pcie_setup_rc() inits the Root Complex subordinate to a
value of 0x01.
Due to this combined with above commit, enumeration stops digging deeper
downstream as soon as bus num 0x01 has been assigned, which is always
the case for a bridge device.
This results in all devices behind a bridge bus to remain undetected, as
these would be connected to bus 0x02 or higher.
Fix this by initializing the RC to a subordinate value of 0xff, meaning
that all busses [0x00-0xff] are reachable through this RC.
Fixes: a20c7f36bd3d ("PCI: Do not allocate more buses than available in
parent")
Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
Tested-by: Niklas Cassel <niklas.cassel@axis.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
---
Will send separate patches to stable as this file got moved/renamed
drivers/pci/host/pcie-designware.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
index bf558df5b7b3..2b5470173196 100644
--- a/drivers/pci/host/pcie-designware.c
+++ b/drivers/pci/host/pcie-designware.c
@@ -861,7 +861,7 @@ void dw_pcie_setup_rc(struct pcie_port *
/* setup bus numbers */
val = dw_pcie_readl_rc(pp, PCI_PRIMARY_BUS);
val &= 0xff000000;
- val |= 0x00010100;
+ val |= 0x00ff0100;
dw_pcie_writel_rc(pp, PCI_PRIMARY_BUS, val);
/* setup command register */