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author | 2023-02-21 18:24:12 -0800 | |
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committer | 2023-02-21 18:24:12 -0800 | |
commit | 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch) | |
tree | cc5c2d0a898769fd59549594fedb3ee6f84e59a0 /drivers/gpio/TODO | |
download | linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip |
Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted
Pull networking updates from Jakub Kicinski:
"Core:
- Add dedicated kmem_cache for typical/small skb->head, avoid having
to access struct page at kfree time, and improve memory use.
- Introduce sysctl to set default RPS configuration for new netdevs.
- Define Netlink protocol specification format which can be used to
describe messages used by each family and auto-generate parsers.
Add tools for generating kernel data structures and uAPI headers.
- Expose all net/core sysctls inside netns.
- Remove 4s sleep in netpoll if carrier is instantly detected on
boot.
- Add configurable limit of MDB entries per port, and port-vlan.
- Continue populating drop reasons throughout the stack.
- Retire a handful of legacy Qdiscs and classifiers.
Protocols:
- Support IPv4 big TCP (TSO frames larger than 64kB).
- Add IP_LOCAL_PORT_RANGE socket option, to control local port range
on socket by socket basis.
- Track and report in procfs number of MPTCP sockets used.
- Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
manager.
- IPv6: don't check net.ipv6.route.max_size and rely on garbage
collection to free memory (similarly to IPv4).
- Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).
- ICMP: add per-rate limit counters.
- Add support for user scanning requests in ieee802154.
- Remove static WEP support.
- Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
reporting.
- WiFi 7 EHT channel puncturing support (client & AP).
BPF:
- Add a rbtree data structure following the "next-gen data structure"
precedent set by recently added linked list, that is, by using
kfunc + kptr instead of adding a new BPF map type.
- Expose XDP hints via kfuncs with initial support for RX hash and
timestamp metadata.
- Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
better support decap on GRE tunnel devices not operating in collect
metadata.
- Improve x86 JIT's codegen for PROBE_MEM runtime error checks.
- Remove the need for trace_printk_lock for bpf_trace_printk and
bpf_trace_vprintk helpers.
- Extend libbpf's bpf_tracing.h support for tracing arguments of
kprobes/uprobes and syscall as a special case.
- Significantly reduce the search time for module symbols by
livepatch and BPF.
- Enable cpumasks to be used as kptrs, which is useful for tracing
programs tracking which tasks end up running on which CPUs in
different time intervals.
- Add support for BPF trampoline on s390x and riscv64.
- Add capability to export the XDP features supported by the NIC.
- Add __bpf_kfunc tag for marking kernel functions as kfuncs.
- Add cgroup.memory=nobpf kernel parameter option to disable BPF
memory accounting for container environments.
Netfilter:
- Remove the CLUSTERIP target. It has been marked as obsolete for
years, and we still have WARN splats wrt races of the out-of-band
/proc interface installed by this target.
- Add 'destroy' commands to nf_tables. They are identical to the
existing 'delete' commands, but do not return an error if the
referenced object (set, chain, rule...) did not exist.
Driver API:
- Improve cpumask_local_spread() locality to help NICs set the right
IRQ affinity on AMD platforms.
- Separate C22 and C45 MDIO bus transactions more clearly.
- Introduce new DCB table to control DSCP rewrite on egress.
- Support configuration of Physical Layer Collision Avoidance (PLCA)
Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
shared medium Ethernet.
- Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
preemption of low priority frames by high priority frames.
- Add support for controlling MACSec offload using netlink SET.
- Rework devlink instance refcounts to allow registration and
de-registration under the instance lock. Split the code into
multiple files, drop some of the unnecessarily granular locks and
factor out common parts of netlink operation handling.
- Add TX frame aggregation parameters (for USB drivers).
- Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
messages with notifications for debug.
- Allow offloading of UDP NEW connections via act_ct.
- Add support for per action HW stats in TC.
- Support hardware miss to TC action (continue processing in SW from
a specific point in the action chain).
- Warn if old Wireless Extension user space interface is used with
modern cfg80211/mac80211 drivers. Do not support Wireless
Extensions for Wi-Fi 7 devices at all. Everyone should switch to
using nl80211 interface instead.
- Improve the CAN bit timing configuration. Use extack to return
error messages directly to user space, update the SJW handling,
including the definition of a new default value that will benefit
CAN-FD controllers, by increasing their oscillator tolerance.
New hardware / drivers:
- Ethernet:
- nVidia BlueField-3 support (control traffic driver)
- Ethernet support for imx93 SoCs
- Motorcomm yt8531 gigabit Ethernet PHY
- onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
- Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
- Amlogic gxl MDIO mux
- WiFi:
- RealTek RTL8188EU (rtl8xxxu)
- Qualcomm Wi-Fi 7 devices (ath12k)
- CAN:
- Renesas R-Car V4H
Drivers:
- Bluetooth:
- Set Per Platform Antenna Gain (PPAG) for Intel controllers.
- Ethernet NICs:
- Intel (1G, igc):
- support TSN / Qbv / packet scheduling features of i226 model
- Intel (100G, ice):
- use GNSS subsystem instead of TTY
- multi-buffer XDP support
- extend support for GPIO pins to E823 devices
- nVidia/Mellanox:
- update the shared buffer configuration on PFC commands
- implement PTP adjphase function for HW offset control
- TC support for Geneve and GRE with VF tunnel offload
- more efficient crypto key management method
- multi-port eswitch support
- Netronome/Corigine:
- add DCB IEEE support
- support IPsec offloading for NFP3800
- Freescale/NXP (enetc):
- support XDP_REDIRECT for XDP non-linear buffers
- improve reconfig, avoid link flap and waiting for idle
- support MAC Merge layer
- Other NICs:
- sfc/ef100: add basic devlink support for ef100
- ionic: rx_push mode operation (writing descriptors via MMIO)
- bnxt: use the auxiliary bus abstraction for RDMA
- r8169: disable ASPM and reset bus in case of tx timeout
- cpsw: support QSGMII mode for J721e CPSW9G
- cpts: support pulse-per-second output
- ngbe: add an mdio bus driver
- usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
- r8152: handle devices with FW with NCM support
- amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
- virtio-net: support multi buffer XDP
- virtio/vsock: replace virtio_vsock_pkt with sk_buff
- tsnep: XDP support
- Ethernet high-speed switches:
- nVidia/Mellanox (mlxsw):
- add support for latency TLV (in FW control messages)
- Microchip (sparx5):
- separate explicit and implicit traffic forwarding rules, make
the implicit rules always active
- add support for egress DSCP rewrite
- IS0 VCAP support (Ingress Classification)
- IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
etc.)
- ES2 VCAP support (Egress Access Control)
- support for Per-Stream Filtering and Policing (802.1Q,
8.6.5.1)
- Ethernet embedded switches:
- Marvell (mv88e6xxx):
- add MAB (port auth) offload support
- enable PTP receive for mv88e6390
- NXP (ocelot):
- support MAC Merge layer
- support for the the vsc7512 internal copper phys
- Microchip:
- lan9303: convert to PHYLINK
- lan966x: support TC flower filter statistics
- lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
- lan937x: support Credit Based Shaper configuration
- ksz9477: support Energy Efficient Ethernet
- other:
- qca8k: convert to regmap read/write API, use bulk operations
- rswitch: Improve TX timestamp accuracy
- Intel WiFi (iwlwifi):
- EHT (Wi-Fi 7) rate reporting
- STEP equalizer support: transfer some STEP (connection to radio
on platforms with integrated wifi) related parameters from the
BIOS to the firmware.
- Qualcomm 802.11ax WiFi (ath11k):
- IPQ5018 support
- Fine Timing Measurement (FTM) responder role support
- channel 177 support
- MediaTek WiFi (mt76):
- per-PHY LED support
- mt7996: EHT (Wi-Fi 7) support
- Wireless Ethernet Dispatch (WED) reset support
- switch to using page pool allocator
- RealTek WiFi (rtw89):
- support new version of Bluetooth co-existance
- Mobile:
- rmnet: support TX aggregation"
* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
page_pool: add a comment explaining the fragment counter usage
net: ethtool: fix __ethtool_dev_mm_supported() implementation
ethtool: pse-pd: Fix double word in comments
xsk: add linux/vmalloc.h to xsk.c
sefltests: netdevsim: wait for devlink instance after netns removal
selftest: fib_tests: Always cleanup before exit
net/mlx5e: Align IPsec ASO result memory to be as required by hardware
net/mlx5e: TC, Set CT miss to the specific ct action instance
net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
net/mlx5: Refactor tc miss handling to a single function
net/mlx5: Kconfig: Make tc offload depend on tc skb extension
net/sched: flower: Support hardware miss to tc action
net/sched: flower: Move filter handle initialization earlier
net/sched: cls_api: Support hardware miss to tc action
net/sched: Rename user cookie and act cookie
sfc: fix builds without CONFIG_RTC_LIB
sfc: clean up some inconsistent indentings
net/mlx4_en: Introduce flexible array to silence overflow warning
net: lan966x: Fix possible deadlock inside PTP
net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
...
Diffstat (limited to 'drivers/gpio/TODO')
-rw-r--r-- | drivers/gpio/TODO | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/drivers/gpio/TODO b/drivers/gpio/TODO new file mode 100644 index 000000000..765607445 --- /dev/null +++ b/drivers/gpio/TODO @@ -0,0 +1,206 @@ +This is a place for planning the ongoing long-term work in the GPIO +subsystem. + + +GPIO descriptors + +Starting with commit 79a9becda894 the GPIO subsystem embarked on a journey +to move away from the global GPIO numberspace and toward a descriptor-based +approach. This means that GPIO consumers, drivers and machine descriptions +ideally have no use or idea of the global GPIO numberspace that has/was +used in the inception of the GPIO subsystem. + +The numberspace issue is the same as to why irq is moving away from irq +numbers to IRQ descriptors. + +The underlying motivation for this is that the GPIO numberspace has become +unmanageable: machine board files tend to become full of macros trying to +establish the numberspace at compile-time, making it hard to add any numbers +in the middle (such as if you missed a pin on a chip) without the numberspace +breaking. + +Machine descriptions such as device tree or ACPI does not have a concept of the +Linux GPIO number as those descriptions are external to the Linux kernel +and treat GPIO lines as abstract entities. + +The runtime-assigned GPIO numberspace (what you get if you assign the GPIO +base as -1 in struct gpio_chip) has also became unpredictable due to factors +such as probe ordering and the introduction of -EPROBE_DEFER making probe +ordering of independent GPIO chips essentially unpredictable, as their base +number will be assigned on a first come first serve basis. + +The best way to get out of the problem is to make the global GPIO numbers +unimportant by simply not using them. GPIO descriptors deal with this. + +Work items: + +- Convert all GPIO device drivers to only #include <linux/gpio/driver.h> + +- Convert all consumer drivers to only #include <linux/gpio/consumer.h> + +- Convert all machine descriptors in "boardfiles" to only + #include <linux/gpio/machine.h>, the other option being to convert it + to a machine description such as device tree, ACPI or fwnode that + implicitly does not use global GPIO numbers. + +- When this work is complete (will require some of the items in the + following ongoing work as well) we can delete the old global + numberspace accessors from <linux/gpio.h> and eventually delete + <linux/gpio.h> altogether. + + +Get rid of <linux/of_gpio.h> + +This header and helpers appeared at one point when there was no proper +driver infrastructure for doing simpler MMIO GPIO devices and there was +no core support for parsing device tree GPIOs from the core library with +the [devm_]gpiod_get() calls we have today that will implicitly go into +the device tree back-end. It is legacy and should not be used in new code. + +Work items: + +- Get rid of struct of_mm_gpio_chip altogether: use the generic MMIO + GPIO for all current users (see below). Delete struct of_mm_gpio_chip, + to_of_mm_gpio_chip(), of_mm_gpiochip_add_data(), of_mm_gpiochip_add() + of_mm_gpiochip_remove() from the kernel. + +- Change all consumer drivers that #include <linux/of_gpio.h> to + #include <linux/gpio/consumer.h> and stop doing custom parsing of the + GPIO lines from the device tree. This can be tricky and often ivolves + changing boardfiles, etc. + +- Pull semantics for legacy device tree (OF) GPIO lookups into + gpiolib-of.c: in some cases subsystems are doing custom flags and + lookups for polarity inversion, open drain and what not. As we now + handle this with generic OF bindings, pull all legacy handling into + gpiolib so the library API becomes narrow and deep and handle all + legacy bindings internally. (See e.g. commits 6953c57ab172, + 6a537d48461d etc) + +- Delete <linux/of_gpio.h> when all the above is complete and everything + uses <linux/gpio/consumer.h> or <linux/gpio/driver.h> instead. + + +Get rid of <linux/gpio.h> + +This legacy header is a one stop shop for anything GPIO is closely tied +to the global GPIO numberspace. The endgame of the above refactorings will +be the removal of <linux/gpio.h> and from that point only the specialized +headers under <linux/gpio/*.h> will be used. This requires all the above to +be completed and is expected to take a long time. + + +Collect drivers + +Collect GPIO drivers from arch/* and other places that should be placed +in drivers/gpio/gpio-*. Augment platforms to create platform devices or +similar and probe a proper driver in the gpiolib subsystem. + +In some cases it makes sense to create a GPIO chip from the local driver +for a few GPIOs. Those should stay where they are. + +At the same time it makes sense to get rid of code duplication in existing or +new coming drivers. For example, gpio-ml-ioh should be incorporated into +gpio-pch. + + +Generic MMIO GPIO + +The GPIO drivers can utilize the generic MMIO helper library in many +cases, and the helper library should be as helpful as possible for MMIO +drivers. (drivers/gpio/gpio-mmio.c) + +Work items: + +- Look over and identify any remaining easily converted drivers and + dry-code conversions to MMIO GPIO for maintainers to test + +- Expand the MMIO GPIO or write a new library for regmap-based I/O + helpers for GPIO drivers on regmap that simply use offsets + 0..n in some register to drive GPIO lines + +- Expand the MMIO GPIO or write a new library for port-mapped I/O + helpers (x86 inb()/outb()) and convert port-mapped I/O drivers to use + this with dry-coding and sending to maintainers to test + + +Generic regmap GPIO + +In the very similar way to Generic MMIO GPIO convert the users which can +take advantage of using regmap over direct IO accessors. Note, even in +MMIO case the regmap MMIO with gpio-regmap.c is preferable over gpio-mmio.c. + + +GPIOLIB irqchip + +The GPIOLIB irqchip is a helper irqchip for "simple cases" that should +try to cover any generic kind of irqchip cascaded from a GPIO. + +- Look over and identify any remaining easily converted drivers and + dry-code conversions to gpiolib irqchip for maintainers to test + + +Increase integration with pin control + +There are already ways to use pin control as back-end for GPIO and +it may make sense to bring these subsystems closer. One reason for +creating pin control as its own subsystem was that we could avoid any +use of the global GPIO numbers. Once the above is complete, it may +make sense to simply join the subsystems into one and make pin +multiplexing, pin configuration, GPIO, etc selectable options in one +and the same pin control and GPIO subsystem. + + +Debugfs in place of sysfs + +The old sysfs code that enables simple uses of GPIOs from the +command line is still popular despite the existance of the proper +character device. The reason is that it is simple to use on +root filesystems where you only have a minimal set of tools such +as "cat", "echo" etc. + +The old sysfs still need to be strongly deprecated and removed +as it relies on the global GPIO numberspace that assume a strict +order of global GPIO numbers that do not change between boots +and is independent of probe order. + +To solve this and provide an ABI that people can use for hacks +and development, implement a debugfs interface to manipulate +GPIO lines that can do everything that sysfs can do today: one +directory per gpiochip and one file entry per line: + +/sys/kernel/debug/gpiochip/gpiochip0 +/sys/kernel/debug/gpiochip/gpiochip0/gpio0 +/sys/kernel/debug/gpiochip/gpiochip0/gpio1 +/sys/kernel/debug/gpiochip/gpiochip0/gpio2 +/sys/kernel/debug/gpiochip/gpiochip0/gpio3 +... +/sys/kernel/debug/gpiochip/gpiochip1 +/sys/kernel/debug/gpiochip/gpiochip1/gpio0 +/sys/kernel/debug/gpiochip/gpiochip1/gpio1 +... + +The exact files and design of the debugfs interface can be +discussed but the idea is to provide a low-level access point +for debugging and hacking and to expose all lines without the +need of any exporting. Also provide ample ammunition to shoot +oneself in the foot, because this is debugfs after all. + + +Moving over to immutable irq_chip structures + +Most of the gpio chips implementing interrupt support rely on gpiolib +intercepting some of the irq_chip callbacks, preventing the structures +from being made read-only and forcing duplication of structures that +should otherwise be unique. + +The solution is to call into the gpiolib code when needed (resource +management, enable/disable or unmask/mask callbacks), and to let the +core code know about that by exposing a flag (IRQCHIP_IMMUTABLE) in +the irq_chip structure. The irq_chip structure can then be made unique +and const. + +A small number of drivers have been converted (pl061, tegra186, msm, +amd, apple), and can be used as examples of how to proceed with this +conversion. Note that drivers using the generic irqchip framework +cannot be converted yet, but watch this space! |