On Wed, Jul 15, 2026 at 01:46:12PM +0300, Cristian Ciocaltea wrote:
> On 7/15/26 11:55 AM, Maxime Ripard wrote:
> > On Mon, Jul 13, 2026 at 01:23:00PM +0300, Cristian Ciocaltea wrote:
> >> On 7/13/26 11:50 AM, Maxime Ripard wrote:
> >>> On Thu, Jul 09, 2026 at 10:25:54PM +0300, Cristian Ciocaltea wrote:
> >>>> On 7/3/26 11:54 PM, Cristian Ciocaltea wrote:
> >>>>> On 7/3/26 5:34 PM, Dmitry Baryshkov wrote:
> >>>>>> On Thu, Jul 02, 2026 at 05:46:17PM +0300, Cristian Ciocaltea wrote:
> >>>>>>> Add the connector-level infrastructure to support HDMI 2.0 scrambling:
> >>>>>>>
> >>>>>>> - A scrambler_supported flag to indicate whether the source supports
> >>>>>>> the
> >>>>>>> scrambling capability, in which case the newly introduced
> >>>>>>> .scrambler_{enable|disable}() callbacks in drm_connector_hdmi_funcs
> >>>>>>> are mandatory
> >>>>>>
> >>>>>> Do we need a flag? What would it mean if the flag is set, but the
> >>>>>> callbacks are not? Can we drop the flag and use the presence of the
> >>>>>> callbacks as a way to identify that scrambler is enabled?
> >>>>>
> >>>>> The flag is intended to be set only within
> >>>>> drmm_connector_hdmi_init_with_caps()
> >>>>> when drivers advertise HDMI 2.x capability, in which case it also
> >>>>> ensures the
> >>>>> callbacks are provided.
> >>>>>
> >>>>> We could drop the flag and instead have the init helper clear the
> >>>>> callbacks if
> >>>>> they were provided for HDMI 1.x. This might slightly reduce code
> >>>>> readability,
> >>>>> as it relies on checking the presence of individual callbacks -
> >>>>> especially since
> >>>>> we plan to extend this further with HDMI 2.1 support, providing four or
> >>>>> five
> >>>>> additional FRL-specific callbacks.
> >>>>
> >>>> I tried to replace the flag with a helper that checks the presence of
> >>>> (one of)
> >>>> the callbacks, but it's not straightforward to unset those for non-HDMI
> >>>> 2.x
> >>>> cases since the hdmi_funcs argument is immutable.
> >>>
> >>> I'm not sure why we would need to unset them. If the driver states that
> >>> it support HDMI 2.0, then it needs to be there, if it doesn't, then who
> >>> cares? it's not going to be used. We can log a warning that it's
> >>> inconsistent I guess, but there's no need to actively remove it.
> >>
> >> I was trying to address the use case where drivers provide the scrambler
> >> callbacks despite not supporting HDMI 2.0.
> >
> > Scrambling got introduced with HDMI 2.0. That doesn't make sense, but
> > it's not a total deal breaker, it's just going to be here unused. Hence
> > why I was suggesting to put a warning there if you wanted to.
> >
> >> If we replace the scrambler_supported flag with a helper checking the
> >> presence of the scrambler callbacks, then we would need to ensure the
> >> callbacks do not exist in this case.
> >
> > Keep it simple:
> >
> > if (hdmi_version >= HDMI_VERSION_2_0)
> > if (funcs->scrambler_enable)
> > hdmi->scramblers_supported = true
> > else
> > return -EINVAL
> > else
> > drm_warn(warn, "Inconsistent HDMI version");
> >
> > We don't need anything more than that.
>
> I dropped the scrambler_supported flag and introduced a helper:
>
> static inline bool
> drm_connector_hdmi_scrambler_supported(struct drm_connector *connector)
> {
> return connector->hdmi.funcs && connector->hdmi.funcs->scrambler_enable;
I'd add disable to that test
> }
>
> Therefore we need to ensure the callbacks are not set in the HDMI 1.x cases:
>
> int drmm_connector_hdmi_init_with_caps()
> {
> ...
> if (caps->supported_hdmi_ver >= HDMI_VERSION_2_0) {
> if (!hdmi_funcs->scrambler_enable ||
> !hdmi_funcs->scrambler_disable)
> return -EINVAL;
>
> connector->hdmi.max_tmds_char_rate =
> HDMI_2_0_TMDS_CHAR_RATE_MAX_HZ;
> } else {
> /*
> * Scrambler callbacks are only valid for connectors advertising
> * HDMI 2.0 capability. drm_connector_hdmi_scrambler_supported()
> * relies on their presence to report scrambling support.
> */
> if (hdmi_funcs->scrambler_enable ||
> hdmi_funcs->scrambler_disable)
> return -EINVAL;
>
> if (caps->supported_hdmi_ver >= HDMI_VERSION_1_3) {
> connector->hdmi.max_tmds_char_rate =
> HDMI_1_3_TMDS_CHAR_RATE_MAX_HZ;
> } else if (caps->supported_hdmi_ver >= HDMI_VERSION_1_0) {
> connector->hdmi.max_tmds_char_rate =
> HDMI_1_0_TMDS_CHAR_RATE_MAX_HZ;
> }
> }
Drivers might have a lower limit than the max allowed by the spec. It
should be provided by the driver, possibly optionally with a fallback to
what the spec states?
Maxime
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