1. 18 10月, 2006 2 次提交
  2. 05 10月, 2006 1 次提交
    • D
      IRQ: Maintain regs pointer globally rather than passing to IRQ handlers · 7d12e780
      David Howells 提交于
      Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
      of passing regs around manually through all ~1800 interrupt handlers in the
      Linux kernel.
      
      The regs pointer is used in few places, but it potentially costs both stack
      space and code to pass it around.  On the FRV arch, removing the regs parameter
      from all the genirq function results in a 20% speed up of the IRQ exit path
      (ie: from leaving timer_interrupt() to leaving do_IRQ()).
      
      Where appropriate, an arch may override the generic storage facility and do
      something different with the variable.  On FRV, for instance, the address is
      maintained in GR28 at all times inside the kernel as part of general exception
      handling.
      
      Having looked over the code, it appears that the parameter may be handed down
      through up to twenty or so layers of functions.  Consider a USB character
      device attached to a USB hub, attached to a USB controller that posts its
      interrupts through a cascaded auxiliary interrupt controller.  A character
      device driver may want to pass regs to the sysrq handler through the input
      layer which adds another few layers of parameter passing.
      
      I've build this code with allyesconfig for x86_64 and i386.  I've runtested the
      main part of the code on FRV and i386, though I can't test most of the drivers.
      I've also done partial conversion for powerpc and MIPS - these at least compile
      with minimal configurations.
      
      This will affect all archs.  Mostly the changes should be relatively easy.
      Take do_IRQ(), store the regs pointer at the beginning, saving the old one:
      
      	struct pt_regs *old_regs = set_irq_regs(regs);
      
      And put the old one back at the end:
      
      	set_irq_regs(old_regs);
      
      Don't pass regs through to generic_handle_irq() or __do_IRQ().
      
      In timer_interrupt(), this sort of change will be necessary:
      
      	-	update_process_times(user_mode(regs));
      	-	profile_tick(CPU_PROFILING, regs);
      	+	update_process_times(user_mode(get_irq_regs()));
      	+	profile_tick(CPU_PROFILING);
      
      I'd like to move update_process_times()'s use of get_irq_regs() into itself,
      except that i386, alone of the archs, uses something other than user_mode().
      
      Some notes on the interrupt handling in the drivers:
      
       (*) input_dev() is now gone entirely.  The regs pointer is no longer stored in
           the input_dev struct.
      
       (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking.  It does
           something different depending on whether it's been supplied with a regs
           pointer or not.
      
       (*) Various IRQ handler function pointers have been moved to type
           irq_handler_t.
      Signed-Off-By: NDavid Howells <dhowells@redhat.com>
      (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
      7d12e780
  3. 04 10月, 2006 1 次提交
  4. 28 9月, 2006 1 次提交
    • T
      USB: ftdi-elan: client driver for ELAN Uxxx adapters · a5c66e4b
      Tony Olech 提交于
      This "ftdi-elan" module is one half of the "driver" for
      ELAN's Uxxx series adapters which are USB to PCMCIA CardBus
      adapters. Currently only the U132 adapter is available and
      it's module is called "u132-hcd".
      
      When the USB hot plug subsystem detects a Uxxx series adapter
      it should load this module.
      
      Upon a successful device probe() the jtag device file interface
      is created and the status workqueue started up.
      
      The jtag device file interface exists for the purpose of
      updating the firmware in the Uxxx series adapter, but as
      yet it had never been used.
      
      The status workqueue initializes the Uxxx and then sits there
      polling the Uxxx until a supported PCMCIA CardBus device is
      detected it will start the command and respond workqueues
      and then load the module that handles the device. This will
      initially be only the u132-hcd module. The status workqueue
      then just polls the Uxxx looking for card ejects.
      
      The command and respond workqueues implement a command
      sequencer for communicating with the firmware on the other
      side of the FTDI chip in the Uxxx. This "ftdi-elan" module
      exports some functions to interface with the sequencer.
      
      Note that this module is a USB client driver.
      
      Note that the "u132-hcd" module is a (cut-down OHCI)
      host controller.
      
      Thus we have a topology with the parent of a host controller
      being a USB client! This really stresses the USB subsystem
      semaphore/mutex handling in the module removal.
      Signed-off-by: NTony Olech <tony.olech@elandigitalsystems.com>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
      
      a5c66e4b