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    SubjectRe: [PATCH v4] drm/i2c: tda998x: fix sync generation and calculation
    On 06/20/2013 10:06 PM, Russell King - ARM Linux wrote:
    > On Thu, Jun 20, 2013 at 09:46:03PM +0200, Sebastian Hesselbarth wrote:
    >> + ref_pix = 3 + mode->hsync_start - mode->hdisplay;
    >> + de_pix_s = mode->htotal - mode->hdisplay;
    >> + de_pix_e = de_pix_s + mode->hdisplay;
    >> + hs_pix_s = mode->hsync_start - mode->hdisplay;
    >> + hs_pix_e = hs_pix_s + mode->hsync_end - mode->hsync_start;
    >
    > Correct, however, these can be simplified.
    [...]
    > These calculations are the same as what was originally in the driver:
    >
    > + de_start = mode->htotal - mode->hdisplay;
    > + de_end = mode->htotal;
    > + hs_start = mode->hsync_start - mode->hdisplay;
    > + hs_end = mode->hsync_end - mode->hdisplay;
    >
    > when it was first committed.
    >
    > This is otherwise exactly what I came up with which gets my TV working
    > again in HDMI mode.

    Russell,

    I am fine with any way to describe de/hs but you should notice that
    I also modified refpix/refline and added interlaced sync. With the
    original sync calculation, on some modes there was source blanking
    captured by TDA998x which was also visible in the output image. I
    chose the above description to make it more readable.

    Also the patch takes care of input sync and output sync inversion
    while the original driver always expected positive HS/VS.

    I tested these sync settings on 4 DVI monitors and TV sets all
    accepted each mode perfectly. Especially, not-so-cheap TV sets
    are very picky about wrong sync.

    Sebastian


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