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    SubjectRe: [PATCH v2 11/11] drm/rockchip/dsi: fix insufficient bandwidth of some panel
    On Mon, 16 Jan 2017 18:08:31 +0800, Chris Zhong wrote:

    > Set the lanes bps to 1 / 0.9 times of pclk, the margin is not enough
    > for some panel, it will cause the screen display is not normal, so
    > increases the badnwidth to 1 / 0.8.
    >
    > Signed-off-by: Chris Zhong <zyw@rock-chips.com>
    >
    > ---
    >
    > drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 4 ++--
    > 1 file changed, 2 insertions(+), 2 deletions(-)
    >
    > diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
    > index 9dfa73d..5a973fe 100644
    > --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
    > +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
    > @@ -501,8 +501,8 @@ static int dw_mipi_dsi_get_lane_bps(struct dw_mipi_dsi *dsi)
    >
    > mpclk = DIV_ROUND_UP(dsi->mode->clock, MSEC_PER_SEC);
    > if (mpclk) {
    > - /* take 1 / 0.9, since mbps must big than bandwidth of RGB */
    > - tmp = mpclk * (bpp / dsi->lanes) * 10 / 9;
    > + /* take 1 / 0.8, since mbps must big than bandwidth of RGB */
    > + tmp = mpclk * (bpp / dsi->lanes) * 10 / 8;

    This and patch 9 are just hacking around the underlying problem in order
    to make particular panels work. I'm pretty sure the actual issue is the
    use of hardcoded values when configuring the PHY, since the PHY
    parameters are specified in clock cycles but the MIPI spec requires
    absolute time durations.

    I posted a series addressing this a while ago, although I screwed up
    sending it so some patches were included twice and since no one
    expressed any interest I didn't post a cleaned up version.

    The relevant patch is here:

    https://patchwork.kernel.org/patch/9340193/

    > if (tmp < max_mbps)
    > target_mbps = tmp;
    > else

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