Re: [PATCH v2 2/2] drm/i915: Add N & CTS values for 10/12 bit deep color

Jani Nikula
2019-05-17T11:31:40Z

On Fri, 17 May 2019, Aditya Swarup <aditya.swarup@intel.com> wrote:
> On Wed, May 15, 2019 at 05:40:10PM +0300, Jani Nikula wrote:
>> On Tue, 02 Apr 2019, Aditya Swarup <aditya.swarup@intel.com> wrote:
>> > Adding N & CTS values for 10/12 bit deep color from Appendix C
>> > table in HDMI 2.0 spec. The correct values for N is not chosen
>> > automatically by hardware for deep color modes.
>> >
>> > v2: Remove redundant code and make it generic.(Jani)
>> >
>> > Signed-off-by: Aditya Swarup <aditya.swarup@intel.com>
>> > Cc: Clint Taylor <Clinton.A.Taylor@intel.com>
>> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> > Cc: Jani Nikula <jani.nikula@intel.com>
>> > Cc: Manasi Navare <manasi.d.navare@intel.com>
>> > ---
>> > drivers/gpu/drm/i915/intel_audio.c | 82 +++++++++++++++++++++++++-----
>> > 1 file changed, 69 insertions(+), 13 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
>> > index 502b57ce72ab..ad53b04fa5a2 100644
>> > --- a/drivers/gpu/drm/i915/intel_audio.c
>> > +++ b/drivers/gpu/drm/i915/intel_audio.c
>> > @@ -70,6 +70,13 @@ struct dp_aud_n_m {
>> > u16 n;
>> > };
>> >
>> > +struct hdmi_aud_ncts_table {
>>
>> The struct itself is not a table. Just make it struct hdmi_ncts or
>> something.
> Will do it in the next spin.
>>
>> > + int sample_rate;
>> > + int clock;
>> > + int n;
>> > + int cts;
>> > +};
>> > +
>> > /* Values according to DP 1.4 Table 2-104 */
>> > static const struct dp_aud_n_m dp_aud_n_m[] = {
>> > { 32000, LC_162M, 1024, 10125 },
>> > @@ -146,12 +153,7 @@ static const struct {
>> > #define TMDS_594M 594000
>> > #define TMDS_593M 593407
>> >
>> > -static const struct {
>> > - int sample_rate;
>> > - int clock;
>> > - int n;
>> > - int cts;
>> > -} hdmi_aud_ncts[] = {
>> > +static const struct hdmi_aud_ncts_table hdmi_aud_ncts_24bpp[] = {
>> > { 32000, TMDS_296M, 5824, 421875 },
>> > { 32000, TMDS_297M, 3072, 222750 },
>> > { 32000, TMDS_593M, 5824, 843750 },
>> > @@ -182,6 +184,49 @@ static const struct {
>> > { 192000, TMDS_594M, 24576, 594000 },
>> > };
>> >
>> > +/* Appendix C - N & CTS values for deep color from HDMI 2.0 spec*/
>> > +/* HDMI N/CTS table for 10 bit deep color(30 bpp)*/
>> > +#define TMDS_371M 371250
>> > +#define TMDS_370M 370878
>> > +
>> > +static const struct hdmi_aud_ncts_table hdmi_aud_ncts_30bpp[] = {
>> > + { 32000, TMDS_370M, 5824, 527344 },
>>
>> N should be 11648?
> The value in the struct is correct. It is 5824 - Appendix C Table C-1 Pg
> 234, for 371.25/1.001 and f = 32kHz => N = 5824

Huh, looks like I have an outdated version of the spec then. For me the
table is on page 232.

Need to find the up-to-date spec, but looking at draft 2.1 the values
you have match.

>>
>> > + { 32000, TMDS_371M, 6144, 556875 },
>> > + { 44100, TMDS_370M, 8918, 585938 },
>>
>> N 17836
> Value in the table is correct.
>>
>> > + { 44100, TMDS_371M, 4704, 309375 },
>> > + { 88200, TMDS_370M, 17836, 585938 },
>>
>> N 35672
> Value in the table is correct.
>>
>> > + { 88200, TMDS_371M, 9408, 309375 },
>> > + { 176400, TMDS_370M, 35672, 585938 },
>>
>> N 71344
> Value in the table is correct.
>>
>> > + { 176400, TMDS_371M, 18816, 309375 },
>> > + { 48000, TMDS_370M, 11648, 703125 },
>> > + { 48000, TMDS_371M, 5120, 309375 },
>> > + { 96000, TMDS_370M, 23296, 703125 },
>> > + { 96000, TMDS_371M, 10240, 309375 },
>> > + { 192000, TMDS_370M, 46592, 703125 },
>> > + { 192000, TMDS_371M, 20480, 309375 },
>> > +};
>> > +
>> > +/* HDMI N/CTS table for 12 bit deep color(36 bpp)*/
>> > +#define TMDS_445_5M 445500
>> > +#define TMDS_445M 445054
>> > +
>> > +static const struct hdmi_aud_ncts_table hdmi_aud_ncts_36bpp[] = {
>> > + { 32000, TMDS_445M, 5824, 632813 },
>> > + { 32000, TMDS_445_5M, 4096, 445500 },
>> > + { 44100, TMDS_445M, 8918, 703125 },
>> > + { 44100, TMDS_445_5M, 4704, 371250 },
>> > + { 88200, TMDS_445M, 17836, 703125 },
>> > + { 88200, TMDS_445_5M, 9408, 371250 },
>> > + { 176400, TMDS_445M, 35672, 703125 },
>> > + { 176400, TMDS_445_5M, 18816, 371250 },
>> > + { 48000, TMDS_445M, 5824, 421875 },
>> > + { 48000, TMDS_445_5M, 5120, 371250 },
>> > + { 96000, TMDS_445M, 11648, 421875 },
>> > + { 96000, TMDS_445_5M, 10240, 371250 },
>> > + { 192000, TMDS_445M, 23296, 421875 },
>> > + { 192000, TMDS_445_5M, 20480, 371250 },
>> > +};
>> > +
>> > /* get AUD_CONFIG_PIXEL_CLOCK_HDMI_* value for mode */
>> > static u32 audio_config_hdmi_pixel_clock(const struct intel_crtc_state *crtc_state)
>> > {
>> > @@ -210,16 +255,27 @@ static u32 audio_config_hdmi_pixel_clock(const struct intel_crtc_state *crtc_sta
>> > static int audio_config_hdmi_get_n(const struct intel_crtc_state *crtc_state,
>> > int rate)
>> > {
>> > - const struct drm_display_mode *adjusted_mode =
>> > - &crtc_state->base.adjusted_mode;
>> > - int i;
>> > + const struct hdmi_aud_ncts_table *hdmi_ncts_table;
>> > + int i, size = 0;
>>
>> Unnecessary initialization.
>>
>> > +
>> > + if (crtc_state->pipe_bpp == 36) {
>> > + hdmi_ncts_table = hdmi_aud_ncts_36bpp;
>> > + size = ARRAY_SIZE(hdmi_aud_ncts_36bpp);
>> > + } else if (crtc_state->pipe_bpp == 30) {
>> > + hdmi_ncts_table = hdmi_aud_ncts_30bpp;
>> > + size = ARRAY_SIZE(hdmi_aud_ncts_30bpp);
>> > + } else {
>> > + hdmi_ncts_table = hdmi_aud_ncts_24bpp;
>> > + size = ARRAY_SIZE(hdmi_aud_ncts_24bpp);
>> > + }
>> >
>> > - for (i = 0; i < ARRAY_SIZE(hdmi_aud_ncts); i++) {
>> > - if (rate == hdmi_aud_ncts[i].sample_rate &&
>> > - adjusted_mode->crtc_clock == hdmi_aud_ncts[i].clock) {
>> > - return hdmi_aud_ncts[i].n;
>> > + for (i = 0; i < size; i++) {
>> ^
>> Superfluous space.
> Will correct it in next spin.
>>
>>
>> > + if (rate == hdmi_ncts_table[i].sample_rate &&
>> > + crtc_state->port_clock == hdmi_ncts_table[i].clock) {
>>
>> Changing from adjusted_mode->crtc_clock to crtc_state->port_clock is a
>> separate change that needs to be a separate patch.
> I don't think it should be a separate change. Working with deep color
> mode requires crtc_state->port_clock as it is scaled according to the
> deep color mode set. Using adjusted_mode->crtc_clock is incorrect as it
> doesn't account for deep color mode; we will have to multiply with
> scaling factor for the set deep color mode which is superfluous.

Make the crtc_clock -> port_clock change *before* the deep color
changes, that's the whole point. Ensure that this change does not impact
non-deep color, and if it does, the bisect will point at the minimal
change. Then add the deep color N & CTS when the code already uses
port_clock.

BR,
Jani.

>
> I can add a comment in the commit message and comment before the if
> block to explain the change. Let me know if it works?
>>
>>
>> BR,
>> Jani.
>>
>> > + return hdmi_ncts_table[i].n;
>> > }
>> > }
>> > +
>> > return 0;
>> > }
>>
>> --
>> Jani Nikula, Intel Open Source Graphics Center
>
> Regards,
> Aditya Swarup

--
Jani Nikula, Intel Open Source Graphics Center