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Tue, 26 Mar 2024 15:40:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1711467657; bh=ZS3wISB0X/kpWLhWogqJqYoscE5+wIH8Om8Y+yVdq+w=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=MTESZzTvtZX7Al2McGXBjbqxhwa2AQckfMaF/LBiQu1AokgzSuzfrXwH0O2lcgOzp owZfBl6UNydsnfN/g3z6rAkIuI3ZjqUlfoW9+lIMh/fDtxEpYjotXpzV1KX+E4zxDB P8l4p27bn5xdWuhR/Blxsknu6JbDsgpUdvOuzJv2Agx6TI9JmmV2zPnV+KvPU9b9LH 6JOLl1djw1Xi2K8fTYer4S+3avm32owl8Y5OqN2hkGIn6kxpDgHys4su7G9mNmPiOx tefmFuwXWB8essZR9Mtkt/qAW/9AhLWzMNbDhR+NsuMhoKkSHp1R1iyfsIRil/7dvU fA6nuVsxGEkIg== From: Maxime Ripard Date: Tue, 26 Mar 2024 16:40:13 +0100 Subject: [PATCH v11 09/28] drm/display: hdmi: Add HDMI compute clock helper Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240326-kms-hdmi-connector-state-v11-9-c5680ffcf261@kernel.org> References: <20240326-kms-hdmi-connector-state-v11-0-c5680ffcf261@kernel.org> In-Reply-To: <20240326-kms-hdmi-connector-state-v11-0-c5680ffcf261@kernel.org> To: Maarten Lankhorst , Thomas Zimmermann , David Airlie , Daniel Vetter , Jonathan Corbet , Sandy Huang , =?utf-8?q?Heiko_St=C3=BCbner?= , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland Cc: Hans Verkuil , Sebastian Wick , =?utf-8?b?VmlsbGUgU3lyasOkbMOk?= , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-sunxi@lists.linux.dev, Maxime Ripard , Dave Stevenson X-Mailer: b4 0.12.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=3675; i=mripard@kernel.org; h=from:subject:message-id; bh=ZS3wISB0X/kpWLhWogqJqYoscE5+wIH8Om8Y+yVdq+w=; b=owGbwMvMwCmsHn9OcpHtvjLG02pJDGlMb5KixIxX/k3k4XbKORnb/3ftnRNWj66qLi8RvX3u5 aclP56/75jKwiDMySArpsjyRCbs9PL2xVUO9it/wMxhZQIZwsDFKQAT+faWseFbTY7Hiv5TDj3/ q39q1M9oLnupqnmu4+i62gVrKlNUPddXHXq9/z57lQ1X/a0WkeL4g4wN7beNNz+dMUvVbUuR2Gn DzjdXg5u7kr+Ul3erOZad+Vx3iJfrnYqtqFjWwfAHyWJvWWoB X-Developer-Key: i=mripard@kernel.org; a=openpgp; fpr=BE5675C37E818C8B5764241C254BCFC56BF6CE8D X-LSpam-Score: -4.1 (----) X-LSpam-Report: No, score=-4.1 required=5.0 tests=ARC_SIGNED=0.001,ARC_VALID=-0.1,BAYES_00=-1.9,DKIMWL_WL_HIGH=-1,DKIM_SIGNED=0.1,DKIM_VALID=-0.1,DKIM_VALID_AU=-0.1,DMARC_PASS=-0.001,MAILING_LIST_MULTI=-1,RCVD_IN_DNSWL_NONE=-0.0001,SPF_HELO_NONE=0.001,SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no A lot of HDMI drivers have some variation of the formula to calculate the TMDS character rate from a mode, but few of them actually take all parameters into account. Let's create a helper to provide that rate taking all parameters into account. Reviewed-by: Dave Stevenson Signed-off-by: Maxime Ripard --- drivers/gpu/drm/display/drm_hdmi_helper.c | 70 +++++++++++++++++++++++++++++++ include/drm/display/drm_hdmi_helper.h | 4 ++ 2 files changed, 74 insertions(+) diff --git a/drivers/gpu/drm/display/drm_hdmi_helper.c b/drivers/gpu/drm/display/drm_hdmi_helper.c index faf5e9efa7d3..2518dd1a07e7 100644 --- a/drivers/gpu/drm/display/drm_hdmi_helper.c +++ b/drivers/gpu/drm/display/drm_hdmi_helper.c @@ -193,5 +193,75 @@ void drm_hdmi_avi_infoframe_content_type(struct hdmi_avi_infoframe *frame, } frame->itc = conn_state->content_type != DRM_MODE_CONTENT_TYPE_NO_DATA; } EXPORT_SYMBOL(drm_hdmi_avi_infoframe_content_type); + +/** + * drm_hdmi_compute_mode_clock() - Computes the TMDS Character Rate + * @mode: Display mode to compute the clock for + * @bpc: Bits per character + * @fmt: Output Pixel Format used + * + * Returns the TMDS Character Rate for a given mode, bpc count and output format. + * + * RETURNS: + * The TMDS Character Rate, in Hertz, or 0 on error. + */ +unsigned long long +drm_hdmi_compute_mode_clock(const struct drm_display_mode *mode, + unsigned int bpc, enum hdmi_colorspace fmt) +{ + unsigned long long clock = mode->clock * 1000ULL; + unsigned int vic = drm_match_cea_mode(mode); + + /* + * CTA-861-G Spec, section 5.4 - Color Coding and Quantization + * mandates that VIC 1 always uses 8 bpc. + */ + if (vic == 1 && bpc != 8) + return 0; + + /* + * HDMI 2.0 Spec, section 7.1 - YCbCr 4:2:0 Pixel Encoding + * specifies that YUV420 encoding is only available for those + * VICs. + */ + if (fmt == HDMI_COLORSPACE_YUV420 && + !(vic == 96 || vic == 97 || vic == 101 || + vic == 102 || vic == 106 || vic == 107)) + return 0; + + if (fmt == HDMI_COLORSPACE_YUV422) { + /* + * HDMI 1.4b Spec, section 6.2.3 - Pixel Encoding Requirements + * specifies that YUV422 is 36-bit only. + */ + if (bpc != 12) + return 0; + + /* + * HDMI 1.0 Spec, section 6.5 - Pixel Encoding + * specifies that YUV422 requires two 12-bits components per + * pixel clock, which is equivalent in our calculation to three + * 8-bits components + */ + bpc = 8; + } + + /* + * HDMI 2.0 Spec, Section 7.1 - YCbCr 4:2:0 Pixel Encoding + * specifies that YUV420 encoding is carried at a TMDS Character Rate + * equal to half the pixel clock rate. + */ + if (fmt == HDMI_COLORSPACE_YUV420) + clock = clock / 2; + + if (mode->flags & DRM_MODE_FLAG_DBLCLK) + clock = clock * 2; + + clock = clock * bpc; + do_div(clock, 8); + + return clock; +} +EXPORT_SYMBOL(drm_hdmi_compute_mode_clock); diff --git a/include/drm/display/drm_hdmi_helper.h b/include/drm/display/drm_hdmi_helper.h index 76d234826e22..57e3b18c15ec 100644 --- a/include/drm/display/drm_hdmi_helper.h +++ b/include/drm/display/drm_hdmi_helper.h @@ -22,6 +22,10 @@ drm_hdmi_infoframe_set_hdr_metadata(struct hdmi_drm_infoframe *frame, const struct drm_connector_state *conn_state); void drm_hdmi_avi_infoframe_content_type(struct hdmi_avi_infoframe *frame, const struct drm_connector_state *conn_state); +unsigned long long +drm_hdmi_compute_mode_clock(const struct drm_display_mode *mode, + unsigned int bpc, enum hdmi_colorspace fmt); + #endif