Todo

Current Linux Kernel TODO List

DMA

• Add optional DMA auto-request support to sh-sci and other blocks.

Timers

• Generic sched_clock() for drivers/clocksource based clocksources.

  • Needs some rework to avoid wrapping, need to investigate interaction with function graph tracer.

Cache and Memory Management

• NUMA emulation on top of the recent LMB/bootmem changes (Paul is theoretically working on this).

• sparsemem vmemmap and extreme.

• highmem.

  • highpte on top of this.

  • Likely restricted to UP given the need to broadcast TLB flushes via software triggered IPIs.

  • Support highmem= for testing with an arbitrary lowmem cutoff.

• Support arbitrary VMSPLIT for PMB systems.

• Killing off MEMORY_START/MEMORY_SIZE in favour of a dynamic model.

  • This will allow for dynamic sizing based off of mode pins as well as for deriving the highmem watermark.

  • Current MEMORY_OFFSET calculation is 0 for virtually every platform already.

  • Boot link offset and zero page offset can be retained for the few platforms that need them.

• Variable page sizes for hugetlb.

• Use large TLBs in ioremap constructed page tables, now that page-table backed ioremap is a common enough operation.

  • Keep this generic, as sparsemem vmemmap will want to use the same mapping strategy.

Power Management

• Run Time

  • Clock Framework

    • Clock Framework for SuperH Mobile:

      • Clock divider extension

        • User space prototype - Done!

      • Cpufreq integration

    • Drivers:

      • Modify SuperH Mobile drivers to use the clock framework:

        • SCIF driver - patches posted!

        • MMC, FLCTL

        • LCD backlight

      • Single shot LCDC mode with SYS panels - Done!

    • UIO:

      • Add basic clock framework support to UIO.

    • Other core code:

      • Modify the interrupt controller and DMA code to use the clock framework.

  • Cpuidle and Sleep Mode, Dynamic Ticks

    • Add Cpuidle support plus Sleep Mode. Optimize with Dynamic ticks.

      • Cpuidle prototype, enter sleep mode - Done!

      • Upstream simple Cpuidle integration

      • Combine with SDRAM self-refresh to save power

  • SDRAM in self-refresh mode:

    • Add platform specific SDRAM code to be able to enter Software Standby.

      • Self-refresh mode prototype through cpuidle - Done!

  • Software Standby Mode Support:

    • Implement and test Software Standby mode, invoke through Cpuidle

      • Software Standby prototype - Done!

  • Frequency and Voltage scaling:

    • Investigate frequency scaling together with voltage scaling.

• Suspend / Resume

  • Save / Restore Ram contents:

    • Make sure we can save and restore memory contents inside kexec_jump.

  • Driver Suspend / Resume support:

    • Verify/Modify common subsystem code suspend support

      • hibernation to mmc is not ok

      • hibernation to usb status is unknown

  • R-Standby Mode Support:

    • Implement and test R-Standby mode using kexec_jump.

  • U-Standby Mode Support:

    • Implement and test U-Standby mode using kexec_jump.

  • Boot loader resume support:

    • Add support for resume from boot loader.

  • Partial Suspend / Resume

    • Allow single drivers to be suspended / resumed for Cpuidle R-Standby Support

General Kernel Features

• CPU hotplug.

• Relocatable kernel support.

• Rework of hard FPU emulation. Tie in to signal context and regset interface (in-progress patch available).

• Write small FPU and DSP test apps in user space from application note code.

• Support IRQ priority setting through generic hardirq layer.

• Support SMP kernel on UP boot for debugging.

• Systematic death of all I/O routines from the machvec, and subsequent conversion to GENERIC_IOMAP.

• Proper .eh_frame generation in vdso

• vsyscall-based gtod / clocksource vread.

  • May require vdso twiddling to behave more as a conventional data page.

• SWIOTLB support needed for PCIe DMA on SH-X3.

• Rework of the thermal subsystem to accommodate the SH-X3 thermal diode. (patch in progress).

• Convert remaining legacy CPG users to new clock framework abstraction.

• clkdev interfacing.

• machine_ops for reset/power control.

• kexec needs to be hw_breakpoint aware.

Drivers

• MFD drivers for SMSC FD37C93xAPM and HD6446x cchips.

• PFC driver updates for upstream GPIO API changes.

  • Also need to tie in GPIO IRQs for platforms that need them (primarily SH-2A).