From: Dominique Martinet <dominique.martinet@xxxxxxxxxxxxxxxxx> This allows the hdmi driver to pick e.g. 64.8MHz instead of 65Mhz when we cannot output the exact frequency, enabling the imx8mp HDMI output to support more modes Tested-by: Adam Ford <aford173@xxxxxxxxx> #imx8mp-beacon Reviewed-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx> Tested-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx> Signed-off-by: Dominique Martinet <dominique.martinet@xxxxxxxxxxxxxxxxx> --- Changes in v2: - Improve comment about the tolerance - Link to v1: https://lore.kernel.org/r/20240904083103.1257480-1-dominique.martinet@xxxxxxxxxxxxxxxxx --- drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c b/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c index 13bc570c5473..200d65184159 100644 --- a/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c +++ b/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c @@ -23,6 +23,7 @@ imx8mp_hdmi_mode_valid(struct dw_hdmi *dw_hdmi, void *data, const struct drm_display_mode *mode) { struct imx8mp_hdmi *hdmi = (struct imx8mp_hdmi *)data; + long round_rate; if (mode->clock < 13500) return MODE_CLOCK_LOW; @@ -30,8 +31,14 @@ imx8mp_hdmi_mode_valid(struct dw_hdmi *dw_hdmi, void *data, if (mode->clock > 297000) return MODE_CLOCK_HIGH; - if (clk_round_rate(hdmi->pixclk, mode->clock * 1000) != - mode->clock * 1000) + round_rate = clk_round_rate(hdmi->pixclk, mode->clock * 1000); + /* imx8mp's pixel clock generator (fsl-samsung-hdmi) cannot generate + * all possible frequencies, so allow some tolerance to support more + * modes. + * Allow 0.5% difference allowed in various standards (VESA, CEA861) + * 0.5% = 5/1000 tolerance (mode->clock is 1/1000) + */ + if (abs(round_rate - mode->clock * 1000) > mode->clock * 5) return MODE_CLOCK_RANGE; /* We don't support double-clocked and Interlaced modes */ --- base-commit: 67784a74e258a467225f0e68335df77acd67b7ab change-id: 20240907-hdmi-tolerance-4d83074a4517 Best regards, -- Dominique Martinet | Asmadeus
