Re: [PATCH v2 2/4] drm/i915: implement set_ncts callback

Yang, Libin
2015-08-11T02:55:01Z

Hi Jani,

> -----Original Message-----
> From: Jani Nikula [mailto:jani.nikula@linux.intel.com]
> Sent: Monday, August 10, 2015 8:17 PM
> To: Yang, Libin; alsa-devel@alsa-project.org; tiwai@suse.de; intel-
> gfx@lists.freedesktop.org; daniel.vetter@ffwll.ch
> Subject: Re: [Intel-gfx] [PATCH v2 2/4] drm/i915: implement set_ncts
> callback
>
> On Mon, 10 Aug 2015, libin.yang@intel.com wrote:
> > From: Libin Yang <libin.yang@intel.com>
> >
> > Display audio may not work at some frequencies
> > with the HW provided N/CTS.
> >
> > This patch sets the proper N value for the
> > given audio sample rate at the impacted frequencies.
> > At other frequencies, it will use the N/CTS value
> > which HW provides.
> >
> > Signed-off-by: Libin Yang <libin.yang@intel.com>
> > ---
> > drivers/gpu/drm/i915/i915_reg.h | 2 +
> > drivers/gpu/drm/i915/intel_audio.c | 95
> ++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 97 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h
> b/drivers/gpu/drm/i915/i915_reg.h
> > index ea46d68..da2d128 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -7014,6 +7014,8 @@ enum skl_disp_power_wells {
> > _HSW_AUD_MISC_CTRL_A, \
> > _HSW_AUD_MISC_CTRL_B)
> >
> > +#define HSW_AUD_PIPE_CONN_SEL_CTRL 0x650ac
> > +
> > #define _HSW_AUD_DIP_ELD_CTRL_ST_A 0x650b4
> > #define _HSW_AUD_DIP_ELD_CTRL_ST_B 0x651b4
> > #define HSW_AUD_DIP_ELD_CTRL(pipe) _PIPE(pipe, \
> > diff --git a/drivers/gpu/drm/i915/intel_audio.c
> b/drivers/gpu/drm/i915/intel_audio.c
> > index dc32cf4..eddf37f 100644
> > --- a/drivers/gpu/drm/i915/intel_audio.c
> > +++ b/drivers/gpu/drm/i915/intel_audio.c
> > @@ -68,6 +68,30 @@ static const struct {
> > { 148500, AUD_CONFIG_PIXEL_CLOCK_HDMI_148500 },
> > };
> >
> > +#define TMDS_297M 297000
> > +#define TMDS_296M DIV_ROUND_UP(297000 * 1000, 1001)
> > +static const struct {
> > + int sample_rate;
> > + int clock;
> > + int n;
> > + int cts;
> > +} aud_ncts[] = {
> > + { 44100, TMDS_296M, 4459, 234375 },
> > + { 44100, TMDS_297M, 4704, 247500 },
> > + { 48000, TMDS_296M, 5824, 281250 },
> > + { 48000, TMDS_297M, 5120, 247500 },
> > + { 32000, TMDS_296M, 5824, 421875 },
> > + { 32000, TMDS_297M, 3072, 222750 },
> > + { 88200, TMDS_296M, 8918, 234375 },
> > + { 88200, TMDS_297M, 9408, 247500 },
> > + { 96000, TMDS_296M, 11648, 281250 },
> > + { 96000, TMDS_297M, 10240, 247500 },
> > + { 176400, TMDS_296M, 17836, 234375 },
> > + { 176400, TMDS_297M, 18816, 247500 },
> > + { 44100, TMDS_296M, 23296, 281250 },
> > + { 44100, TMDS_297M, 20480, 247500 },
> > +};
> > +
> > /* get AUD_CONFIG_PIXEL_CLOCK_HDMI_* value for mode */
> > static u32 audio_config_hdmi_pixel_clock(struct drm_display_mode
> *mode)
> > {
> > @@ -514,12 +538,83 @@ static int
> i915_audio_component_get_cdclk_freq(struct device *dev)
> > return ret;
> > }
> >
> > +static int i915_audio_component_set_ncts(struct device *dev, int
> port,
> > + int dev_entry, int rate)
> > +{
> > + struct drm_i915_private *dev_priv = dev_to_i915(dev);
> > + struct drm_device *drm_dev = dev_priv->dev;
> > + struct intel_encoder *intel_encoder;
> > + struct intel_digital_port *intel_dig_port;
> > + struct intel_crtc *crtc;
> > + struct drm_display_mode *mode;
> > + enum pipe pipe = -1;
> > + u32 tmp;
> > + int i;
> > + int n_low, n_up, n = 0;
>
> I think you'll need the power well get here, and put at the end. Or
> check that we it.

As we only need set the n/cts when playing the audio,
this can make sure that audio driver has already required
the power before we call the callback function.

Regards,
Libin

>
> > +
> > + /* 1. get the pipe */
> > + for_each_intel_encoder(drm_dev, intel_encoder) {
> > + intel_dig_port = enc_to_dig_port(&intel_encoder-
> >base);
> > + if (port == intel_dig_port->port) {
> > + crtc = to_intel_crtc(intel_encoder->base.crtc);
> > + if (!crtc) {
> > + DRM_DEBUG_KMS("%s: crtc is NULL\n",
> __func__);
> > + continue;
> > + }
> > + pipe = crtc->pipe;
> > + break;
> > + }
> > + }
> > +
> > + if (pipe == -1) {
> > + DRM_DEBUG_KMS("no pipe for the port %c\n",
> port_name(port));
> > + return -ENODEV;
> > + }
> > + DRM_DEBUG_KMS("pipe %c connects port %c\n",
> > + pipe_name(pipe), port_name(port));
> > + mode = &crtc->config->base.adjusted_mode;
> > +
> > + /* 2. Need set the N/CTS manually at some frequencies */
> > + if ((mode->clock != TMDS_297M) &&
> > + (mode->clock != TMDS_296M)) {
> > + tmp = I915_READ(HSW_AUD_CFG(pipe));
> > + tmp &= ~AUD_CONFIG_N_PROG_ENABLE;
> > + I915_WRITE(HSW_AUD_CFG(pipe), tmp);
> > + return 0;
> > + }
> > +
> > + /* 3. calculate the N/CTS */
> > + for (i = 0; i < ARRAY_SIZE(aud_ncts); i++) {
> > + if ((rate == aud_ncts[i].sample_rate) &&
> > + (mode->clock == aud_ncts[i].clock)) {
> > + n = aud_ncts[i].n;
> > + break;
> > + }
> > + }
> > + if (n == 0)
> > + return 0;
> > + n_low = n & 0xfff;
> > + n_up = (n >> 12) & 0xff;
> > +
> > + /* 4. set the N/CTS */
> > + tmp = I915_READ(HSW_AUD_CFG(pipe));
> > + tmp |= AUD_CONFIG_N_PROG_ENABLE;
> > + tmp &= ~AUD_CONFIG_UPPER_N_MASK;
> > + tmp |= (n_up << AUD_CONFIG_UPPER_N_SHIFT);
> > + tmp &= ~AUD_CONFIG_LOWER_N_MASK;
> > + tmp |= (n_low << AUD_CONFIG_LOWER_N_SHIFT);
> > + I915_WRITE(HSW_AUD_CFG(pipe), tmp);
> > +
> > + return 0;
> > +}
> > +
> > static const struct i915_audio_component_ops
> i915_audio_component_ops = {
> > .owner = THIS_MODULE,
> > .get_power = i915_audio_component_get_power,
> > .put_power = i915_audio_component_put_power,
> > .codec_wake_override =
> i915_audio_component_codec_wake_override,
> > .get_cdclk_freq = i915_audio_component_get_cdclk_freq,
> > + .set_ncts = i915_audio_component_set_ncts,
> > };
> >
> > static int i915_audio_component_bind(struct device *i915_dev,
> > --
> > 1.9.1
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Jani Nikula, Intel Open Source Technology Center