Hi Lorenzo,

Thanks a lot for your comments!

-----Original Message-----
From: Lorenzo Pieralisi <redacted>
Sent: 2019年6月12日 1:18
To: Z.q. Hou <zhiqiang.hou@nxp.com>; bhelgaas@google.com
Cc: linux-pci@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
devicetree@vger.kernel.org; linux-kernel@vger.kernel.org;
robh+dt@kernel.org; mark.rutland@arm.com; l.subrahmanya@mobiveil.co.in;
shawnguo@kernel.org; Leo Li [off-list ref];
catalin.marinas@arm.com; will.deacon@arm.com; Mingkai Hu
[off-list ref]; M.h. Lian [off-list ref]; Xiaowei Bao
[off-list ref]
Subject: Re: [PATCHv5 16/20] PCI: mobiveil: Add link up condition check

NB: Please trim the CC list and keep it to concerned maintainers.

On Fri, Apr 12, 2019 at 08:36:48AM +0000, Z.q. Hou wrote:

quoted

From: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>

Avoid to issue CFG transactions to link partner when the PCIe link is
not up.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
---
V5:
 - Corrected the subject.

 drivers/pci/controller/pcie-mobiveil.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/pci/controller/pcie-mobiveil.c

b/drivers/pci/controller/pcie-mobiveil.c
index 621852078caf..1ee3ea2570c0 100644

--- a/drivers/pci/controller/pcie-mobiveil.c
+++ b/drivers/pci/controller/pcie-mobiveil.c

@@ -283,6 +283,10 @@ static bool mobiveil_pcie_valid_device(struct

pci_bus *bus, unsigned int devfn)  {
 	struct mobiveil_pcie *pcie = bus->sysdata;

+	/* If there is no link, then there is no device */
+	if (bus->number > pcie->root_bus_nr && !mobiveil_pcie_link_up(pcie))

I think Bjorn mentioned this a million times already, eg:

https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.ke
rnel.org%2Flinux-pci%2F20190411201535.GS256045%40google.com%2F&am
p;data=02%7C01%7Czhiqiang.hou%40nxp.com%7Cffb4c8dcebe4493a375908
d6ee90b471%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C63695
8702637973543&sdata=m%2FqV5zohqyBMUDT7zrVjF%2FLtYeJZO36rdY
eMTPGGbHg%3D&reserved=0

this is racy and gives a false sense of robustness. We have code in the kernel
that checks the link but adding more seems silly to me, so I am inclined to
drop this patch.

Understand, drop it.

Thanks,
Zhiqiang

Lorenzo

quoted

+		return false;
+
 	/* Only one device down on each root port */
 	if ((bus->number == pcie->root_bus_nr) && (devfn > 0))
 		return false;
--
2.17.1

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