• French, Nicholas A's avatar
    media: ivtv: add parameter to enable ivtvfb on x86 PAT systems · 526daee7
    French, Nicholas A authored
    ivtvfb was previously disabled for x86 PAT-enabled systems
    by commit 1bf1735b ("x86/mm/pat, drivers/media/ivtv:
    Use arch_phys_wc_add() and require PAT disabled") as a
    workaround to abstract MTRR code away from device drivers.
    
    The driver is not easily upgradable to the PAT-aware
    ioremap_wc() API since the firmware hides the address
    ranges that should be marked write-combined from the driver.
    However, since a write-combined cache on the framebuffer
    is only a performance enhancement not a requirement for
    the framebuffer to function, completely disabling the driver
    in this configuration is not necessary.
    
    Add force_pat module parameter and a corresponding kernel
    configuration parameter to optionally force initialization
    on PAT-enabled x86 systems with a warning about the lack of
    write-combined caching, and document the reasons the driver
    cannot be easily updated to support wc caching on all systems.
    Signed-off-by: default avatarNick French <naf@ou.edu>
    Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
    [hverkuil-cisco@xs4all.nl: fix typo, split long pr_ lines up]
    Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
    526daee7
Kconfig 3 KB