| Message ID | 20240907-hdmi-tolerance-v2-1-b9d7abd89f5c@codewreck.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] drm/bridge: imx8mp-hdmi-tx: allow 0.5% margin with selected clock | expand |
On 07/09/2024 07:54, Dominique Martinet wrote: > From: Dominique Martinet <dominique.martinet@atmark-techno.com> > > 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@gmail.com> #imx8mp-beacon > Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de> > Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de> > Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com> > --- > Changes in v2: > - Improve comment about the tolerance > - Link to v1: https://lore.kernel.org/r/20240904083103.1257480-1-dominique.martinet@atmark-techno.com > --- > 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, Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Hi, On Sat, 07 Sep 2024 14:54:33 +0900, Dominique Martinet wrote: > 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 > > Thanks, Applied to https://gitlab.freedesktop.org/drm/misc/kernel.git (drm-misc-next) [1/1] drm/bridge: imx8mp-hdmi-tx: allow 0.5% margin with selected clock https://gitlab.freedesktop.org/drm/misc/kernel/-/commit/0d4b950e03fb1c1873c51916fd01ebafbbc48222
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 */