From patchwork Mon May 27 13:57:58 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxime Ripard X-Patchwork-Id: 13675316 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2DD0EC25B7D for ; Mon, 27 May 2024 13:58:58 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id BE21310ECB4; Mon, 27 May 2024 13:58:56 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="I9G8+k01"; dkim-atps=neutral Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by gabe.freedesktop.org (Postfix) with ESMTPS id AF2DB10EB73 for ; Mon, 27 May 2024 13:58:37 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 4377FCE0F97; Mon, 27 May 2024 13:58:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 636A9C2BBFC; Mon, 27 May 2024 13:58:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1716818313; bh=sYS5+n6ti3SenQa49tm4bqlTuOZg4jHrSUyiizUUoAM=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=I9G8+k01SfK5/SDQ0dsSZfYTz/aBsAfQ5i8wwxoeBs+KBqdAAPaKBgwxmqyPzWUz3 JVzZVHe8xZg3l43xHIbBB709Hp+51muysfbIVu7+64Ytx+VWiiM8SvvSwzYKhnznC7 Tc0eF3oTU3RNpi0cGQrkE3/WSf4HbbnjjnFeBPF9H5o+B2JdA3ppqwYxP18JymGFf4 ObF+4ale1SUf6uYOS4TbWvFWBtvhnXjI69MrdI36+qhJ48UmumCYKmpjDQOQ1//Ril 8Pj+9BMjg3qsamCmpu6WlF+5TIssPs3YJlfbmX7mi8l8n6wqZHi6UNDvu4w0LnhUUA /m7ihdit19D4Q== From: Maxime Ripard Date: Mon, 27 May 2024 15:57:58 +0200 Subject: [PATCH v15 09/29] drm/display: hdmi: Add HDMI compute clock helper MIME-Version: 1.0 Message-Id: <20240527-kms-hdmi-connector-state-v15-9-c5af16c3aae2@kernel.org> References: <20240527-kms-hdmi-connector-state-v15-0-c5af16c3aae2@kernel.org> In-Reply-To: <20240527-kms-hdmi-connector-state-v15-0-c5af16c3aae2@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 , Andy Yan 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 0.13.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3575; i=mripard@kernel.org; h=from:subject:message-id; bh=sYS5+n6ti3SenQa49tm4bqlTuOZg4jHrSUyiizUUoAM=; b=owGbwMvMwCmsHn9OcpHtvjLG02pJDGkhE5OlGY5tfujwfSMnz6r+nWVnS29s+j/1molvLe/p8 Lf7HE8xd0xlYRDmZJAVU2R5IhN2enn74ioH+5U/YOawMoEMYeDiFICJTD7F2HDT2VqsJGSDRdDF bUU63V5xJ6I6jvsZaXO++PhexHdjgOyF24eO3+pff3Zx517NxVfrtzE2TFCre/fDa2oYy9OjDG2 3Wufzr3jA9ZVzeudiLtNOn4eu03rUZ6g/meeZP/X15a+RvxPXAAA= X-Developer-Key: i=mripard@kernel.org; a=openpgp; fpr=BE5675C37E818C8B5764241C254BCFC56BF6CE8D X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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 Reviewed-by: Dmitry Baryshkov --- drivers/gpu/drm/display/drm_hdmi_helper.c | 61 +++++++++++++++++++++++++++++++ include/drm/display/drm_hdmi_helper.h | 4 ++ 2 files changed, 65 insertions(+) diff --git a/drivers/gpu/drm/display/drm_hdmi_helper.c b/drivers/gpu/drm/display/drm_hdmi_helper.c index faf5e9efa7d3..74dd4d01dd9b 100644 --- a/drivers/gpu/drm/display/drm_hdmi_helper.c +++ b/drivers/gpu/drm/display/drm_hdmi_helper.c @@ -193,5 +193,66 @@ 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; + + if (fmt == HDMI_COLORSPACE_YUV422) { + /* + * HDMI 1.0 Spec, section 6.5 - Pixel Encoding states that + * YUV422 sends 24 bits over three channels, with Cb and Cr + * components being sent on odd and even pixels, respectively. + * + * If fewer than 12 bpc are sent, data are left justified. + */ + if (bpc > 12) + return 0; + + /* + * HDMI 1.0 Spec, section 6.5 - Pixel Encoding + * specifies that YUV422 sends two 12-bits components over + * three TMDS channels per pixel clock, which is equivalent to + * three 8-bits components over three channels used by RGB as + * far as the clock rate goes. + */ + 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; + + return DIV_ROUND_CLOSEST_ULL(clock * bpc, 8); +} +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