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From: "Z.q. Hou" <zhiqiang.hou@nxp.com>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	"bhelgaas@google.com" <bhelgaas@google.com>
Cc: "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"l.subrahmanya@mobiveil.co.in" <l.subrahmanya@mobiveil.co.in>,
	"shawnguo@kernel.org" <shawnguo@kernel.org>,
	Leo Li <leoyang.li@nxp.com>,
	"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"will.deacon@arm.com" <will.deacon@arm.com>,
	Mingkai Hu <mingkai.hu@nxp.com>,
	"M.h. Lian" <minghuan.lian@nxp.com>,
	Xiaowei Bao <xiaowei.bao@nxp.com>
Subject: RE: [PATCHv5 16/20] PCI: mobiveil: Add link up condition check
Date: Wed, 12 Jun 2019 11:36:45 +0000
Message-ID: <AM0PR04MB673830A6DF6FEDFC9155037184EC0@AM0PR04MB6738.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <20190611171733.GB22836@redmoon>

Hi Lorenzo,

Thanks a lot for your comments!

> -----Original Message-----
> From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Sent: 2019Äê6ÔÂ12ÈÕ 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 <leoyang.li@nxp.com>;
> catalin.marinas@arm.com; will.deacon@arm.com; Mingkai Hu
> <mingkai.hu@nxp.com>; M.h. Lian <minghuan.lian@nxp.com>; Xiaowei Bao
> <xiaowei.bao@nxp.com>
> 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:
> > 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&amp;sdata=m%2FqV5zohqyBMUDT7zrVjF%2FLtYeJZO36rdY
> eMTPGGbHg%3D&amp;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
> 
> > +		return false;
> > +
> >  	/* Only one device down on each root port */
> >  	if ((bus->number == pcie->root_bus_nr) && (devfn > 0))
> >  		return false;
> > --
> > 2.17.1
> >

  reply index

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-12  8:35 [PATCHv5 00/20] PCI: mobiveil: fixes for Mobiveil PCIe Host Bridge IP driver Z.q. Hou
2019-04-12  8:35 ` [PATCHv5 01/20] PCI: mobiveil: Unify register accessors Z.q. Hou
2019-04-12  8:35 ` [PATCHv5 02/20] PCI: mobiveil: Format the code without functionality change Z.q. Hou
2019-07-03 15:10   ` Lorenzo Pieralisi
2019-07-04  2:41     ` Z.q. Hou
2019-07-03 15:19   ` Lorenzo Pieralisi
2019-07-03 15:24     ` Lorenzo Pieralisi
2019-07-04  3:00     ` Z.q. Hou
2019-07-04 10:56       ` Lorenzo Pieralisi
2019-07-05  2:24         ` Z.q. Hou
2019-04-12  8:35 ` [PATCHv5 03/20] PCI: mobiveil: Correct the returned error number Z.q. Hou
2019-07-03 14:17   ` Lorenzo Pieralisi
2019-07-04  2:38     ` Z.q. Hou
2019-04-12  8:35 ` [PATCHv5 04/20] PCI: mobiveil: Remove the flag MSI_FLAG_MULTI_PCI_MSI Z.q. Hou
2019-06-11 16:59   ` Lorenzo Pieralisi
2019-06-11 17:29     ` Marc Zyngier
2019-06-12 10:54       ` Lorenzo Pieralisi
2019-06-12 11:22       ` Marc Zyngier
2019-06-12 11:34     ` Z.q. Hou
2019-06-12 13:08       ` Lorenzo Pieralisi
2019-06-15  1:30         ` Z.q. Hou
2019-06-17  9:33           ` Lorenzo Pieralisi
2019-06-17 10:34             ` Z.q. Hou
2019-06-28 11:35               ` Lorenzo Pieralisi
2019-07-01 10:07                 ` Z.q. Hou
2019-04-12  8:35 ` [PATCHv5 05/20] PCI: mobiveil: Correct PCI base address in MEM/IO outbound windows Z.q. Hou
2019-04-12  8:35 ` [PATCHv5 06/20] PCI: mobiveil: Replace the resource list iteration function Z.q. Hou
2019-04-12  8:35 ` [PATCHv5 07/20] PCI: mobiveil: Use WIN_NUM_0 explicitly for CFG outbound window Z.q. Hou
2019-06-12 15:13   ` Lorenzo Pieralisi
2019-04-12  8:36 ` [PATCHv5 08/20] PCI: mobiveil: Use the 1st inbound window for MEM inbound transactions Z.q. Hou
2019-06-28 16:02   ` Lorenzo Pieralisi
2019-07-01 10:18     ` Z.q. Hou
2019-04-12  8:36 ` [PATCHv5 09/20] PCI: mobiveil: Correct inbound/outbound window setup routines Z.q. Hou
2019-06-28 16:41   ` Lorenzo Pieralisi
2019-07-01 10:24     ` Z.q. Hou
2019-04-12  8:36 ` [PATCHv5 10/20] PCI: mobiveil: Fix the INTx process errors Z.q. Hou
2019-06-12 15:08   ` Lorenzo Pieralisi
2019-06-14  7:08     ` Karthikeyan Mitran
2019-06-14 10:43       ` Lorenzo Pieralisi
2019-06-19  5:28         ` Karthikeyan Mitran
2019-06-19  7:24           ` Z.q. Hou
2019-06-28 17:05   ` Lorenzo Pieralisi
2019-07-01 10:27     ` Z.q. Hou
2019-04-12  8:36 ` [PATCHv5 11/20] PCI: mobiveil: Correct the fixup of Class Code field Z.q. Hou
2019-04-12  8:36 ` [PATCHv5 12/20] PCI: mobiveil: Move the link up waiting out of mobiveil_host_init() Z.q. Hou
2019-04-12  8:36 ` [PATCHv5 13/20] PCI: mobiveil: Move IRQ chained handler setup out of DT parse Z.q. Hou
2019-04-12  8:36 ` [PATCHv5 14/20] PCI: mobiveil: Initialize Primary/Secondary/Subordinate bus numbers Z.q. Hou
2019-04-12  8:36 ` [PATCHv5 15/20] PCI: mobiveil: Fix the checking of valid device Z.q. Hou
2019-04-12  8:36 ` [PATCHv5 16/20] PCI: mobiveil: Add link up condition check Z.q. Hou
2019-06-11 17:17   ` Lorenzo Pieralisi
2019-06-12 11:36     ` Z.q. Hou [this message]
2019-04-12  8:36 ` [PATCHv5 17/20] PCI: mobiveil: Complete initialization of host even if no PCIe link Z.q. Hou
2019-06-12 14:34   ` Lorenzo Pieralisi
2019-06-15  2:34     ` Z.q. Hou
2019-04-12  8:37 ` [PATCHv5 18/20] PCI: mobiveil: Disable IB and OB windows set by bootloader Z.q. Hou
2019-06-12 16:23   ` Lorenzo Pieralisi
2019-06-15  5:03     ` Z.q. Hou
2019-06-17  9:30       ` Lorenzo Pieralisi
2019-06-17 10:42         ` Z.q. Hou
2019-04-12  8:37 ` [PATCHv5 19/20] PCI: mobiveil: Add 8-bit and 16-bit register accessors Z.q. Hou
2019-06-12 13:54   ` Lorenzo Pieralisi
2019-06-15  1:13     ` Z.q. Hou
2019-06-17  9:29       ` Lorenzo Pieralisi
2019-06-17 10:16         ` Z.q. Hou
2019-04-12  8:37 ` [PATCHv5 20/20] dt-bindings: PCI: mobiveil: Change gpio_slave and apb_csr to optional Z.q. Hou
2019-07-03 10:33 ` [PATCHv5 00/20] PCI: mobiveil: fixes for Mobiveil PCIe Host Bridge IP driver Lorenzo Pieralisi
2019-07-04  2:36   ` Z.q. Hou

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