01 Nov, 2011

1 commit


30 Mar, 2010

1 commit

  • …it slab.h inclusion from percpu.h

    percpu.h is included by sched.h and module.h and thus ends up being
    included when building most .c files. percpu.h includes slab.h which
    in turn includes gfp.h making everything defined by the two files
    universally available and complicating inclusion dependencies.

    percpu.h -> slab.h dependency is about to be removed. Prepare for
    this change by updating users of gfp and slab facilities include those
    headers directly instead of assuming availability. As this conversion
    needs to touch large number of source files, the following script is
    used as the basis of conversion.

    http://userweb.kernel.org/~tj/misc/slabh-sweep.py

    The script does the followings.

    * Scan files for gfp and slab usages and update includes such that
    only the necessary includes are there. ie. if only gfp is used,
    gfp.h, if slab is used, slab.h.

    * When the script inserts a new include, it looks at the include
    blocks and try to put the new include such that its order conforms
    to its surrounding. It's put in the include block which contains
    core kernel includes, in the same order that the rest are ordered -
    alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
    doesn't seem to be any matching order.

    * If the script can't find a place to put a new include (mostly
    because the file doesn't have fitting include block), it prints out
    an error message indicating which .h file needs to be added to the
    file.

    The conversion was done in the following steps.

    1. The initial automatic conversion of all .c files updated slightly
    over 4000 files, deleting around 700 includes and adding ~480 gfp.h
    and ~3000 slab.h inclusions. The script emitted errors for ~400
    files.

    2. Each error was manually checked. Some didn't need the inclusion,
    some needed manual addition while adding it to implementation .h or
    embedding .c file was more appropriate for others. This step added
    inclusions to around 150 files.

    3. The script was run again and the output was compared to the edits
    from #2 to make sure no file was left behind.

    4. Several build tests were done and a couple of problems were fixed.
    e.g. lib/decompress_*.c used malloc/free() wrappers around slab
    APIs requiring slab.h to be added manually.

    5. The script was run on all .h files but without automatically
    editing them as sprinkling gfp.h and slab.h inclusions around .h
    files could easily lead to inclusion dependency hell. Most gfp.h
    inclusion directives were ignored as stuff from gfp.h was usually
    wildly available and often used in preprocessor macros. Each
    slab.h inclusion directive was examined and added manually as
    necessary.

    6. percpu.h was updated not to include slab.h.

    7. Build test were done on the following configurations and failures
    were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
    distributed build env didn't work with gcov compiles) and a few
    more options had to be turned off depending on archs to make things
    build (like ipr on powerpc/64 which failed due to missing writeq).

    * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
    * powerpc and powerpc64 SMP allmodconfig
    * sparc and sparc64 SMP allmodconfig
    * ia64 SMP allmodconfig
    * s390 SMP allmodconfig
    * alpha SMP allmodconfig
    * um on x86_64 SMP allmodconfig

    8. percpu.h modifications were reverted so that it could be applied as
    a separate patch and serve as bisection point.

    Given the fact that I had only a couple of failures from tests on step
    6, I'm fairly confident about the coverage of this conversion patch.
    If there is a breakage, it's likely to be something in one of the arch
    headers which should be easily discoverable easily on most builds of
    the specific arch.

    Signed-off-by: Tejun Heo <tj@kernel.org>
    Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

    Tejun Heo
     

15 Jul, 2008

1 commit


30 Nov, 2007

1 commit

  • The code in fb_ddc_read() is said to be based on the implementation of the
    radeon driver:
    http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=fc5891c8a3ba284f13994d7bc1f1bfa8283982de

    However, comparing the old radeon driver code with the new fb_ddc code
    reveals some differences. Most notably, the I2C bus lines are held at the
    end of the function, while the original code was releasing them (as the
    comment above correctly says.)

    There are a few other differences, which appear to be responsible for read
    failures on my system. While tracing low-level I2C code in i2c-algo-bit, I
    noticed that the initial attempt to read the EDID always failed. It takes
    one retry for the read to succeed. As we are about to remove this
    automatic retry property from i2c-algo-bit, reading the EDID would really
    fail.

    As a summary, the I2C lines quirk which is supposedly needed to read EDID
    on some older monitors is currently breaking the (first) read on all other
    monitors (and might not even work with older ones - did anyone try since
    October 2006?)

    After applying the patch below, which makes the code in fb_ddc_read()
    really similar to what the radeon driver used to have, the first EDID read
    succeeds again.

    On top of that, as it appears that this code has been broken for one year
    now and nobody seems to have complained, I'm curious if it makes sense to
    keep this quirk in place. It makes the code more complex and slower just
    for the sake of monitors which I guess nobody uses anymore. Can't we just
    get rid of it?

    Signed-off-by: Jean Delvare
    Acked-by: Benjamin Herrenschmidt
    Tested-by: Roger Leigh
    Tested-by: Michael Buesch
    Cc: "Antonino A. Daplas"
    Cc:
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Jean Delvare
     

17 Nov, 2006

1 commit

  • Benh points out that the msgs[0].flags entry never got initialized, and
    since it's an automatic stack allocation, it could have any random
    value, which is bad.

    Rewrite the initializer to explicitly initialize all fields of the small
    i2c_msg structure array we generate. Just to keep it all obvious, let's
    handle msgs[1].buf in the same initializer while we're at it, instead of
    initializing that one separately later.

    Signed-off-by: Linus Torvalds

    Linus Torvalds
     

03 Oct, 2006

1 commit

  • Adds functionality to read the EDID information over the DDC bus in a generic
    way. This code is based on the DDC implementation in the radeon driver.

    [adaplas]
    - separate from fbmon.c and place in new file fb_ddc.c
    - remove dependency to CONFIG_I2C and CONFIG_I2C_ALGOBIT, otherwise, feature
    will not compile if i2c support is compiled as a module
    - feature is selectable only by drivers needing it. It must have a
    'select FB_DDC if xxx' in Kconfig
    - change printk's to dev_*, the i2c people prefers it

    Signed-off-by: Dennis Munsie
    Signed-off-by: Antonino Daplas
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Dennis Munsie