On 25-01-07 10:30:29, Johan Hovold wrote:
> On Fri, Jan 03, 2025 at 02:58:15PM +0200, Abel Vesa wrote:
> > According to the DisplayPort standard, LTTPRs have two operating
> > modes:
> > - non-transparent - it replies to DPCD LTTPR field specific AUX
> > requests, while passes through all other AUX requests
> > - transparent - it passes through all AUX requests.
> >
> > Switching between this two modes is done by the DPTX by issuing
> > an AUX write to the DPCD PHY_REPEATER_MODE register.
> >
> > Add a generic helper that allows switching between these modes.
> >
> > Also add a generic wrapper for the helper that handles the explicit
> > disabling of non-transparent mode and its disable->enable sequence
> > mentioned in the DP Standard v2.0 section 3.6.6.1. Do this in order
> > to move this handling out of the vendor specific driver implementation
> > into the generic framework.
> >
> > Tested-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
> > Signed-off-by: Abel Vesa <abel.vesa@xxxxxxxxxx>
>
> > +/**
> > + * drm_dp_lttpr_init - init LTTPR transparency mode according to DP standard
> > + *
> > + * @aux: DisplayPort AUX channel
> > + * @lttpr_count: Number of LTTPRs. Between 0 and 8, according to DP standard.
> > + * Negative error code for any non-valid number.
> > + * See drm_dp_lttpr_count().
> > + *
> > + * Returns 0 on success or a negative error code on failure.
> > + */
> > +int drm_dp_lttpr_init(struct drm_dp_aux *aux, int lttpr_count)
> > +{
> > + int ret;
> > +
> > + if (!lttpr_count)
> > + return 0;
> > +
> > + /*
> > + * See DP Standard v2.0 3.6.6.1 about the explicit disabling of
> > + * non-transparent mode and the disable->enable non-transparent mode
> > + * sequence.
> > + */
> > + ret = drm_dp_lttpr_set_transparent_mode(aux, true);
> > + if (ret)
> > + return ret;
> > +
> > + if (lttpr_count < 0)
> > + return -ENODEV;
> > +
> > + /*
> > + * Roll-back to tranparent mode if setting non-tranparent mode failed
>
> typo: transparent (2x)
Will fix.
>
> > + */
>
> I think this comment now needs to go inside the conditional, if you want
> to keep it at all.
Yes, will move it.
>
> > + if (drm_dp_lttpr_set_transparent_mode(aux, false)) {
> > + drm_dp_lttpr_set_transparent_mode(aux, true);
> > + return -EINVAL;
> > + }
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL(drm_dp_lttpr_init);
>
> This looks much better to me now, so with the above addressed:
>
> Reviewed-by: Johan Hovold <johan+linaro@xxxxxxxxxx>
Thanks for reviewing!
Abel
