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kernel: backport dwc pci enumeration fix

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Backport of:  http://patchwork.ozlabs.org/patch/860701/

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Tested-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
This commit is contained in:
Tim Harvey 2018-02-15 08:34:35 -08:00 committed by John Crispin
parent cc8921162f
commit 3282e7189f
1 changed files with 62 additions and 0 deletions
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target/linux/generic/pending-4.14/812-pci-dwc-fix-enumeration.patch Normal file
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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/dwc/pcie-designware-host.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pci/dwc/pcie-designware-host.c b/drivers/pci/dwc/pcie-designware-host.c
index bf558df5b7b3..2b5470173196 100644
--- a/drivers/pci/dwc/pcie-designware-host.c
+++ b/drivers/pci/dwc/pcie-designware-host.c
@@ -616,7 +616,7 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
/* setup bus numbers */
val = dw_pcie_readl_dbi(pci, PCI_PRIMARY_BUS);
val &= 0xff000000;
- val |= 0x00010100;
+ val |= 0x00ff0100;
dw_pcie_writel_dbi(pci, PCI_PRIMARY_BUS, val);
/* setup command register */