| Message ID | 20190412083635.33626-17-Zhiqiang.Hou@nxp.com |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | PCI: mobiveil: fixes for Mobiveil PCIe Host Bridge IP driver | expand |
| Context | Check | Description |
|---|---|---|
| robh/checkpatch | success |
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://lore.kernel.org/linux-pci/20190411201535.GS256045@google.com/ 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. 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 >
Hi Lorenzo, Thanks a lot for your comments! > -----Original Message----- > From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> > 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 <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&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 > > > + return false; > > + > > /* Only one device down on each root port */ > > if ((bus->number == pcie->root_bus_nr) && (devfn > 0)) > > return false; > > -- > > 2.17.1 > >
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)) + return false; + /* Only one device down on each root port */ if ((bus->number == pcie->root_bus_nr) && (devfn > 0)) return false;