On Mon, 2022-02-14 at 09:16 +0000, Maciej W. Rozycki wrote: > On Mon, 14 Feb 2022, Geert Uytterhoeven wrote: > > > > The only PCI platforms that actually can't make use of PC-style parallel > > > port hardware are those newer PCIe systems that have no support for I/O > > > cycles in the host bridge, required by such parallel ports. An example > > > of such a host bridge is the POWER9 PHB4 device, but it is an exception > > > rather than the norm. Also it is not clear whether the serial port side > > > > Note that this hardware dependency is being addressed in > > "[RFC 00/32] Kconfig: Introduce HAS_IOPORT and LEGACY_PCI options" > > https://lore.kernel.org/all/20211227164317.4146918-1-schnelle@xxxxxxxxxxxxx/ > > Thanks for the pointer, I have missed the series in the LKML flood! > > The idea sounds good, although it's not clear to me if a config option is > enough to get it properly covered as I don't know offhand if a single say > ppc64le kernel can't run on systems that do and do not have support for > port I/O over PCIe. I got hit with that the hard way with a distribution > kernel where a driver tried to do port I/O and poked at a random location > in the address space causing weird errors to be reported by the system > firmware. > > Also I have skimmed over the series and there appears to be confusion > between legacy PCI and conventional PCI, which are obviously not the same. > For example this piece: > > diff --git a/drivers/net/fddi/Kconfig b/drivers/net/fddi/Kconfig > index 846bf41c2717..1753c08d6423 100644 > --- a/drivers/net/fddi/Kconfig > +++ b/drivers/net/fddi/Kconfig > @@ -5,7 +5,7 @@ > > config FDDI > tristate "FDDI driver support" > - depends on PCI || EISA || TC > + depends on LEGACY_PCI || EISA || TC > help > Fiber Distributed Data Interface is a high speed local area network > design; essentially a replacement for high speed Ethernet. FDDI can > @@ -29,7 +29,7 @@ config DEFZA > > config DEFXX > tristate "Digital DEFTA/DEFEA/DEFPA adapter support" > - depends on FDDI && (PCI || EISA || TC) > + depends on FDDI && (LEGACY_PCI || EISA || TC) > help > This is support for the DIGITAL series of TURBOchannel (DEFTA), > EISA (DEFEA) and PCI (DEFPA) controllers which can connect you > > is clearly wrong. While the DEFPA card is a conventional PCI option it > does support MMIO and does run with my legacy-free POWER9 system just > fine (with a suitable PCIe-to-PCI bridge installed at 0031:01:00.0): > > # lspci > 0000:00:00.0 PCI bridge: IBM POWER9 Host Bridge (PHB4) > 0001:00:00.0 PCI bridge: IBM POWER9 Host Bridge (PHB4) > 0001:01:00.0 Serial controller: Oxford Semiconductor Ltd OXPCIe952 Dual Native 950 UART > 0002:00:00.0 PCI bridge: IBM POWER9 Host Bridge (PHB4) > 0002:01:00.0 Serial Attached SCSI controller: Adaptec Series 8 12G SAS/PCIe 3 (rev 01) > 0003:00:00.0 PCI bridge: IBM POWER9 Host Bridge (PHB4) > 0003:01:00.0 USB controller: Texas Instruments TUSB73x0 SuperSpeed USB 3.0 xHCI Host Controller (rev 02) > 0004:00:00.0 PCI bridge: IBM POWER9 Host Bridge (PHB4) > 0004:01:00.0 Ethernet controller: Broadcom Inc. and subsidiaries NetXtreme BCM5719 Gigabit Ethernet PCIe (rev 01) > 0004:01:00.1 Ethernet controller: Broadcom Inc. and subsidiaries NetXtreme BCM5719 Gigabit Ethernet PCIe (rev 01) > 0005:00:00.0 PCI bridge: IBM POWER9 Host Bridge (PHB4) > 0005:01:00.0 PCI bridge: ASPEED Technology, Inc. AST1150 PCI-to-PCI Bridge (rev 04) > 0005:02:00.0 VGA compatible controller: ASPEED Technology, Inc. ASPEED Graphics Family (rev 41) > 0030:00:00.0 PCI bridge: IBM POWER9 Host Bridge (PHB4) > 0030:01:00.0 PCI bridge: PMC-Sierra Inc. PM8562 Switchtec PFX-L 32xG3 Fanout-Lite PCIe Gen3 Switch > 0030:02:00.0 PCI bridge: PMC-Sierra Inc. PM8562 Switchtec PFX-L 32xG3 Fanout-Lite PCIe Gen3 Switch > 0030:02:01.0 PCI bridge: PMC-Sierra Inc. PM8562 Switchtec PFX-L 32xG3 Fanout-Lite PCIe Gen3 Switch > 0030:02:02.0 PCI bridge: PMC-Sierra Inc. PM8562 Switchtec PFX-L 32xG3 Fanout-Lite PCIe Gen3 Switch > 0030:02:03.0 PCI bridge: PMC-Sierra Inc. PM8562 Switchtec PFX-L 32xG3 Fanout-Lite PCIe Gen3 Switch > 0030:03:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM981/PM981/PM983 > 0030:04:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM981/PM981/PM983 > 0030:05:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM981/PM981/PM983 > 0030:06:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM981/PM981/PM983 > 0031:00:00.0 PCI bridge: IBM POWER9 Host Bridge (PHB4) > 0031:01:00.0 PCI bridge: Texas Instruments XIO2000(A)/XIO2200A PCI Express-to-PCI Bridge (rev 03) > 0031:02:04.0 FDDI network controller: Digital Equipment Corporation PCI-to-PDQ Interface Chip [PFI] FDDI (DEFPA) (rev 02) > 0031:02:05.0 ATM network controller: Microsemi / PMC / IDT IDT77201/77211 155Mbps ATM SAR Controller [NICStAR] (rev 03) > 0032:00:00.0 PCI bridge: IBM POWER9 Host Bridge (PHB4) > 0033:00:00.0 PCI bridge: IBM POWER9 Host Bridge (PHB4) > # dmesg | grep 0031:02:04.0 | cut -c16- > pci 0031:02:04.0: [1011:000f] type 00 class 0x020200 > pci 0031:02:04.0: reg 0x10: [mem 0x620c080020000-0x620c08002007f] > pci 0031:02:04.0: reg 0x14: [io 0x0000-0x007f] > pci 0031:02:04.0: reg 0x18: [mem 0x620c080030000-0x620c08003ffff] > pci 0031:02:04.0: BAR0 [mem size 0x00000080]: requesting alignment to 0x10000 > pci 0031:02:04.0: BAR 0: assigned [mem 0x620c080020000-0x620c08002007f] > pci 0031:02:04.0: BAR 2: assigned [mem 0x620c080030000-0x620c08003ffff] > pci 0031:02:04.0: BAR 1: no space for [io size 0x0080] > pci 0031:02:04.0: BAR 1: failed to assign [io size 0x0080] > pci 0031:02:04.0: Configured PE#fc > pci 0031:02:04.0: Adding to iommu group 9 > defxx 0031:02:04.0: enabling device (0140 -> 0142) > 0031:02:04.0: DEFPA at MMIO addr = 0x620c080020000, IRQ = 57, Hardware addr = 00-60-6d-93-91-98 > 0031:02:04.0: registered as fddi0 > $ ip link show dev fddi0 > 4: fddi0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 4470 qdisc pfifo_fast > state UNKNOWN mode DEFAULT group default qlen 100 > link/fddi 00:60:6d:93:91:98 brd ff:ff:ff:ff:ff:ff > $ > > While older versions of the driver did have to be explicitly configured > for MMIO rather than port I/O, a feature added with commit e89a2cfb7d7b > ("[TC] defxx: TURBOchannel support"), the driver has been improved with > commit 795e272e5474 ("FDDI: defxx: Implement dynamic CSR I/O address space > selection") and the selection of the I/O space to use now fully automatic. Very interesting and thanks for the input! On s390 we really only have very few different PCI devices and I can only test another hand full with my private x86 and ARM systems. > > Then what about the other FDDI driver there, SKFP? It's not marked as > LEGACY_PCI, although it's not selectable anyway due to the dependency of > FDDI on LEGACY_PCI. > > Niklas, what was the criterion for placing the LEGACY_PCI dependency? Hmm, honestly I haven't really worked on this recently. There were some open questions from Bjorn towards Arnd and I was waiting for his reply but I guess he missed those. I think what you noticed was the main problem, there wasn't really a clear set of criteria for LEGACY_PCI and even for HAS_IOPORT we missed some uses if they were not compiled on s390's allyesconfig due to other dependencies. > > Also do you plan to post an updated series anytime soon? I'm asking > because like with the m68k port also the MIPS one needs a more finegrained > approach and I suspect there may be other corner cases and I'd rather look > at the most recent version of your series. Otherwise I'll have a look > through your original submission, but it may have to wait until the next > weekend due to my other commitments. > > Maciej That sounds like you do see a need for something like HAS_IOPORT too, correct? Maybe with some input what you need and possibly stripping the LEGACY_PCI option it might make sense to do a new version. Rather than possibly getting in your way could directly work in your input.
