Eric Lee / smarc-fsl-linux-kernel

15 Jul, 2008

1 commit

30 Nov, 2007

1 commit

  • b64d70825   fb_ddc: fix DDC lines quirk ... Browse Code »

    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

  • 4be703906   Fix generic fb_ddc i2c edid probe msg ... Browse Code »

    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

  • fc5891c8a   [PATCH] fbdev: Add generic ddc read functionality ... Browse Code »

    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