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SubjectRe: [Intel-gfx] [RFC 1/5] drm/i915/dp: Program source OUI on eDP panels
Date
On Tue, 15 Sep 2020, Rodrigo Vivi <rodrigo.vivi@intel.com> wrote:
> 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.

(For whatever reason I didn't receive the original message.)

>>
>> 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?

An OUI lookup confirms these are Intel OUI.

>
>> 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");
>> +}

Maybe add this function with a parameter to force write or write only if
necessary, and call from both places that set source OUI?

>> +
>> 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?

Mmh, this just exposes sink behaviour that I think can be supported by
any platform. I don't understand the notion of "supported platforms"
here.

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

--
Jani Nikula, Intel Open Source Graphics Center

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