• Linus Walleij's avatar
    drm/bridge: sii902x: Retry status read after DDI I2C · 2e7a66a8
    Linus Walleij authored
    The following happens when connection a DVI output driven
    from the SiI9022 using a DVI-to-VGA adapter plug:
    
    i2c i2c-0: sendbytes: NAK bailout.
    i2c i2c-0: sendbytes: NAK bailout.
    
    Then no picture. Apparently the I2C engine inside the SiI9022
    is not smart enough to try to fall back to DDC I2C. Or the
    vendor have not integrated the electronics properly. I don't
    know which one it is.
    
    After this, the I2C bus seems stalled and the first attempt to
    read the status register fails, and the code returns with
    negative return value, and the display fails to initialized.
    
    Instead, retry status readout five times and continue even
    if this fails.
    
    Tested on the ARM Versatile Express with a DVI-to-VGA
    connector, it now gives picture.
    
    Introduce a helper struct device *dev variable to make
    the code more readable.
    
    Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
    Reviewed-by: default avatarLiviu Dudau <Liviu.Dudau@arm.com>
    Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
    Link: https://patchwork.freedesktop.org/patch/msgid/20180305101702.13441-1-linus.walleij@linaro.org
    2e7a66a8
sii902x.c 12.9 KB