Multiple drivers for same hardware:, was: DRM and pci_driver conversion

From: Jon Smirl (jonsmirl_at_yahoo.com)
Date: 10/24/03

  • Next message: Randolph Chung: "[patch] fix __div64_32 to do division properly" 
    Date:	Thu, 23 Oct 2003 20:47:01 -0700 (PDT)
To: Jeff Garzik <jgarzik@pobox.com>, Linus Torvalds <torvalds@osdl.org>

    What about the fundamental question? We have several pairs of device drivers
    that want to control the same hardware. One example would be radeon DRM and
    radeon Framebuffer. How should these drivers coordinate probing and claiming
    resources?

    What should be the policy for multiple drivers?
    1) try new probe first and fall back to old scheme. First driver that loads
    gets the new probe, second gets the old. First driver reserves resources.
    2) Require a mini driver that handles probing. Then both drivers attach to the
    mini driver.
    3) Declare it illegal and make the drivers merge.
    4) Declare it illegal and only allow first one loaded to run.

    Right now radeonfb handles probing and resource reservation. DRM works in
    stealth mode. DRM uses all of the resources and never tells the kernel, that's
    how it avoids conflicting with framebuffer.

    DRM and framebuffer trade off control at VT switch. 2D state is save and
    restored. There is an assumption that framebuffer won't mess with the 3D state.
     I'm not sure that suspend/resume are coordinated in any way.

    =====
    Jon Smirl
    jonsmirl@yahoo.com

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  • Next message: Randolph Chung: "[patch] fix __div64_32 to do division properly"

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