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SubjectRe: [RFC 1/5] drm/i915/dp: Program source OUI on eDP panels
On Tue, Sep 15, 2020 at 01:29:35PM -0400, Lyude Paul wrote:
> Since we're about to start adding support for Intel's magic HDR
> backlight interface over DPCD, we need to ensure we're properly
> programming this field so that Intel specific sink services are exposed.
> Otherwise, 0x300-0x3ff will just read zeroes.
>
> We also take care not to reprogram the source OUI if it already matches
> what we expect. This is just to be careful so that we don't accidentally
> take the panel out of any backlight control modes we found it in.
>
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> Cc: thaytan@noraisin.net
> Cc: Vasily Khoruzhick <anarsoul@gmail.com>
> ---
> drivers/gpu/drm/i915/display/intel_dp.c | 32 +++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 4bd10456ad188..b591672ec4eab 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -3428,6 +3428,7 @@ void intel_dp_sink_set_decompression_state(struct intel_dp *intel_dp,
> void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode)
> {
> struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> + u8 edp_oui[] = { 0x00, 0xaa, 0x01 };

what are these values?

> int ret, i;
>
> /* Should have a valid DPCD by this point */
> @@ -3443,6 +3444,14 @@ void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode)
> } else {
> struct intel_lspcon *lspcon = dp_to_lspcon(intel_dp);
>
> + /* Write the source OUI as early as possible */
> + if (intel_dp_is_edp(intel_dp)) {
> + ret = drm_dp_dpcd_write(&intel_dp->aux, DP_SOURCE_OUI, edp_oui,
> + sizeof(edp_oui));
> + if (ret < 0)
> + drm_err(&i915->drm, "Failed to write eDP source OUI\n");
> + }
> +
> /*
> * When turning on, we need to retry for 1ms to give the sink
> * time to wake up.
> @@ -4530,6 +4539,23 @@ static void intel_dp_get_dsc_sink_cap(struct intel_dp *intel_dp)
> }
> }
>
> +static void
> +intel_edp_init_source_oui(struct intel_dp *intel_dp)
> +{
> + struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> + u8 oui[] = { 0x00, 0xaa, 0x01 };
> + u8 buf[3] = { 0 };
> +
> + if (drm_dp_dpcd_read(&intel_dp->aux, DP_SOURCE_OUI, buf, sizeof(buf)) < 0)
> + drm_err(&i915->drm, "Failed to read source OUI\n");
> +
> + if (memcmp(oui, buf, sizeof(oui)) == 0)
> + return;
> +
> + if (drm_dp_dpcd_write(&intel_dp->aux, DP_SOURCE_OUI, oui, sizeof(oui)) < 0)
> + drm_err(&i915->drm, "Failed to write source OUI\n");
> +}
> +
> static bool
> intel_edp_init_dpcd(struct intel_dp *intel_dp)
> {
> @@ -4607,6 +4633,12 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
> if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv))
> intel_dp_get_dsc_sink_cap(intel_dp);
>
> + /*
> + * Program our source OUI so we can make various Intel-specific AUX
> + * services available (such as HDR backlight controls)
> + */
> + intel_edp_init_source_oui(intel_dp);

I believe we should restrict this to the supported platforms: cfl, whl, cml, icl, tgl
no?

> +
> return true;
> }
>
> --
> 2.26.2
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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