Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933639AbdDGOYJ (ORCPT ); Fri, 7 Apr 2017 10:24:09 -0400 Received: from mail-wr0-f172.google.com ([209.85.128.172]:33818 "EHLO mail-wr0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932534AbdDGOYC (ORCPT ); Fri, 7 Apr 2017 10:24:02 -0400 Subject: Re: [PATCH 2/2] drm: dw-hdmi: Gate audio clock from the I2S enablement callbacks To: Romain Perier , Archit Taneja , David Airlie References: <20170407141905.14147-1-romain.perier@collabora.com> <20170407141905.14147-3-romain.perier@collabora.com> Cc: dri-devel@lists.freedesktop.org, linux-rockchip@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Jose Abreu , Russell King From: Neil Armstrong Organization: Baylibre Message-ID: <984b7a29-81a8-8404-0c76-d632b4ae9a9d@baylibre.com> Date: Fri, 7 Apr 2017 16:23:57 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <20170407141905.14147-3-romain.perier@collabora.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2732 Lines: 76 On 04/07/2017 04:19 PM, Romain Perier wrote: > Currently, the audio sampler clock is enabled from dw_hdmi_setup() at > step E. and is kept enabled for later use. This clock should be enabled > and disabled along with the actual audio stream and not always on (that > is bad for PM). Futhermore, as described by the datasheet, the I2S > variant need to gate/ungate the clock when the stream is > enabled/disabled. > > This commit adds a parameter to hdmi_audio_enable_clk() that controls > when the audio sample clock must be enabled or disabled. Then, it adds > the call to this function from dw_hdmi_i2s_audio_enable() and > dw_hdmi_i2s_audio_disable(). > > Signed-off-by: Romain Perier > --- > drivers/gpu/drm/bridge/dw-hdmi.c | 16 +++++++++------- > 1 file changed, 9 insertions(+), 7 deletions(-) > > diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c > index d34e0a5..3bd0807 100644 > --- a/drivers/gpu/drm/bridge/dw-hdmi.c > +++ b/drivers/gpu/drm/bridge/dw-hdmi.c > @@ -559,6 +559,12 @@ void dw_hdmi_set_sample_rate(struct dw_hdmi *hdmi, unsigned int rate) > } > EXPORT_SYMBOL_GPL(dw_hdmi_set_sample_rate); > > +static void hdmi_enable_audio_clk(struct dw_hdmi *hdmi, bool enable) > +{ > + hdmi_modb(hdmi, enable ? 0 : HDMI_MC_CLKDIS_AUDCLK_DISABLE, > + HDMI_MC_CLKDIS_AUDCLK_DISABLE, HDMI_MC_CLKDIS); > +} > + > void dw_hdmi_ahb_audio_enable(struct dw_hdmi *hdmi) > { > hdmi_set_cts_n(hdmi, hdmi->audio_cts, hdmi->audio_n); > @@ -572,12 +578,13 @@ void dw_hdmi_ahb_audio_disable(struct dw_hdmi *hdmi) > void dw_hdmi_i2s_audio_enable(struct dw_hdmi *hdmi) > { > hdmi_set_cts_n(hdmi, hdmi->audio_cts, hdmi->audio_n); > + hdmi_enable_audio_clk(hdmi, true); > } > > > void dw_hdmi_i2s_audio_disable(struct dw_hdmi *hdmi) > { > - > + hdmi_enable_audio_clk(hdmi, false); > } I think the NULL check is still valid if you fill this function, because the IP also support other modes (SPDIF and GPA). > > void dw_hdmi_audio_enable(struct dw_hdmi *hdmi) > @@ -1365,11 +1372,6 @@ static void dw_hdmi_enable_video_path(struct dw_hdmi *hdmi) > } > } > > -static void hdmi_enable_audio_clk(struct dw_hdmi *hdmi) > -{ > - hdmi_modb(hdmi, 0, HDMI_MC_CLKDIS_AUDCLK_DISABLE, HDMI_MC_CLKDIS); > -} > - > /* Workaround to clear the overflow condition */ > static void dw_hdmi_clear_overflow(struct dw_hdmi *hdmi) > { > @@ -1471,7 +1473,7 @@ static int dw_hdmi_setup(struct dw_hdmi *hdmi, struct drm_display_mode *mode) > > /* HDMI Initialization Step E - Configure audio */ > hdmi_clk_regenerator_update_pixel_clock(hdmi); > - hdmi_enable_audio_clk(hdmi); > + hdmi_enable_audio_clk(hdmi, true); > } > > /* not for DVI mode */ >