From: Andrew Jackson <Andrew.Jackson@arm.com> To: Russell King - ARM Linux <linux@arm.linux.org.uk>, Dave Airlie <airlied@gmail.com>, "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> Cc: Liviu Dudau <Liviu.Dudau@arm.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org> Subject: [PATCH] drm/i2c: tda998x: Allow for different audio sample rates Date: Tue, 18 Nov 2014 17:39:30 +0000 [thread overview] Message-ID: <546B8452.6030701@arm.com> (raw) On HDMI, the audio data are carried across the HDMI link which is driven by the TDMS clock. The TDMS clock is dependent on the video pixel rate. This patch sets the denominator (Cycle Time Stamp) appropriately allowing the driver to send audio to a wider range of HDMI sinks (i.e. monitors). Signed-off-by: Andrew Jackson <Andrew.Jackson@arm.com> --- drivers/gpu/drm/i2c/tda998x_drv.c | 22 ++++++++++++++++++---- 1 files changed, 18 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c index d476279..da0d504 100644 --- a/drivers/gpu/drm/i2c/tda998x_drv.c +++ b/drivers/gpu/drm/i2c/tda998x_drv.c @@ -640,7 +640,7 @@ tda998x_configure_audio(struct tda998x_priv *priv, struct drm_display_mode *mode, struct tda998x_encoder_params *p) { uint8_t buf[6], clksel_aip, clksel_fs, cts_n, adiv; - uint32_t n; + uint32_t n, cts; /* Enable audio ports */ reg_write(priv, REG_ENA_AP, p->audio_cfg); @@ -696,9 +696,23 @@ tda998x_configure_audio(struct tda998x_priv *priv, n = 128 * p->audio_sample_rate / 1000; /* Write the CTS and N values */ - buf[0] = 0x44; - buf[1] = 0x42; - buf[2] = 0x01; + if ((n > 0) && (mode->clock > 0)) { + /* + * For non-coherent clocks, the average CTS value is + * calculated as: + * fTMDS * n / (128 * fs) + * which simplifies to: + * fTMDS / 1000 + * (See sections 7.2.2 and 7.2.3 of the HDMI specification.) + * NB mode->clock is in kHz. + */ + cts = mode->clock; + } else { + cts = 82500; + } + buf[0] = cts; + buf[1] = cts >> 8; + buf[2] = cts >> 16; buf[3] = n; buf[4] = n >> 8; buf[5] = n >> 16; -- 1.7.1
WARNING: multiple messages have this Message-ID (diff)
From: Andrew.Jackson@arm.com (Andrew Jackson) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] drm/i2c: tda998x: Allow for different audio sample rates Date: Tue, 18 Nov 2014 17:39:30 +0000 [thread overview] Message-ID: <546B8452.6030701@arm.com> (raw) On HDMI, the audio data are carried across the HDMI link which is driven by the TDMS clock. The TDMS clock is dependent on the video pixel rate. This patch sets the denominator (Cycle Time Stamp) appropriately allowing the driver to send audio to a wider range of HDMI sinks (i.e. monitors). Signed-off-by: Andrew Jackson <Andrew.Jackson@arm.com> --- drivers/gpu/drm/i2c/tda998x_drv.c | 22 ++++++++++++++++++---- 1 files changed, 18 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c index d476279..da0d504 100644 --- a/drivers/gpu/drm/i2c/tda998x_drv.c +++ b/drivers/gpu/drm/i2c/tda998x_drv.c @@ -640,7 +640,7 @@ tda998x_configure_audio(struct tda998x_priv *priv, struct drm_display_mode *mode, struct tda998x_encoder_params *p) { uint8_t buf[6], clksel_aip, clksel_fs, cts_n, adiv; - uint32_t n; + uint32_t n, cts; /* Enable audio ports */ reg_write(priv, REG_ENA_AP, p->audio_cfg); @@ -696,9 +696,23 @@ tda998x_configure_audio(struct tda998x_priv *priv, n = 128 * p->audio_sample_rate / 1000; /* Write the CTS and N values */ - buf[0] = 0x44; - buf[1] = 0x42; - buf[2] = 0x01; + if ((n > 0) && (mode->clock > 0)) { + /* + * For non-coherent clocks, the average CTS value is + * calculated as: + * fTMDS * n / (128 * fs) + * which simplifies to: + * fTMDS / 1000 + * (See sections 7.2.2 and 7.2.3 of the HDMI specification.) + * NB mode->clock is in kHz. + */ + cts = mode->clock; + } else { + cts = 82500; + } + buf[0] = cts; + buf[1] = cts >> 8; + buf[2] = cts >> 16; buf[3] = n; buf[4] = n >> 8; buf[5] = n >> 16; -- 1.7.1
next reply other threads:[~2014-11-18 17:40 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-11-18 17:39 Andrew Jackson [this message] 2014-11-18 17:39 ` [PATCH] drm/i2c: tda998x: Allow for different audio sample rates Andrew Jackson 2014-11-18 17:39 ` Andrew Jackson 2014-11-18 18:00 ` Russell King - ARM Linux 2014-11-18 18:00 ` Russell King - ARM Linux 2014-11-18 18:00 ` Russell King - ARM Linux 2014-11-19 11:21 ` Andrew Jackson 2014-11-19 11:21 ` Andrew Jackson 2014-11-19 11:21 ` Andrew Jackson
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