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h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=GIudKkeoDkMn+BtPXzwCpS6xMMrGuBZ7UV0fROChdqK4tX3gTXq98vHz2Bl/MaCPT /cAT78VQ9RE3ne+lj4+xlS/m4QvUEk+c37XfyIBPDL6OZ7YHWjfpfLyqmFpmDsop+r CzVLcXvjeWpVuq6xpe/X+fD+35WvgxTGJgvaQHnNrEXAMOvCQEZMdrT86sQzc/tB6h npjDzMohXJUalDiYu7oPusTqBamuw8+4a6I2+v9s5ORSv+u2xTk2VgISUoJ6VjZ63r XJeijMh219Wgf2GjpVlsoO0ZdEqUFyGGdVD4EXSrLQFDvcXwX1CONHaS6ZIxryGQOf 3QaVuZIaZDGhQ== From: Maxime Ripard Date: Thu, 07 Mar 2024 14:38:35 +0100 Subject: [PATCH v8 08/27] drm/connector: hdmi: Add HDMI compute clock helper MIME-Version: 1.0 Message-Id: <20240307-kms-hdmi-connector-state-v8-8-ef6a6f31964b@kernel.org> References: <20240307-kms-hdmi-connector-state-v8-0-ef6a6f31964b@kernel.org> In-Reply-To: <20240307-kms-hdmi-connector-state-v8-0-ef6a6f31964b@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=4451; i=mripard@kernel.org; h=from:subject:message-id; bh=knNLcwVqg8jv1l/rgrHhTRsj59b8/zn3xoeOIeIyJfk=; b=owGbwMvMwCX2+D1vfrpE4FHG02pJDKkvDye8FffR6jZ5UdDre3Ujn+Omhbc/L9T6ee1s1WcPr 617Nu6611HKwiDGxSArpsgSI2y+JO7UrNedbHzzYOawMoEMYeDiFICJZE5k+O/gJsh9RN9fcILC px9r4m5tPCu7xeeNnuR+C5+CiwUSR/8zMqxlU/9f+vOk/O+/M7sXNgu0q31uso5d6hzooJ6aNPc OAzMA X-Developer-Key: i=mripard@kernel.org; a=openpgp; fpr=BE5675C37E818C8B5764241C254BCFC56BF6CE8D X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240307_133928_273756_268383CB X-CRM114-Status: GOOD ( 14.65 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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/drm_connector.c | 71 +++++++++++++++++++++++++++++++++++++++++ include/drm/drm_connector.h | 5 +++ 2 files changed, 76 insertions(+) diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c index b629c8e990f4..8cc1332f11c2 100644 --- a/drivers/gpu/drm/drm_connector.c +++ b/drivers/gpu/drm/drm_connector.c @@ -2895,10 +2895,81 @@ void drm_connector_update_privacy_screen(const struct drm_connector_state *conne /* The hw_state property value may have changed, update it. */ drm_connector_update_privacy_screen_properties(connector, false); } EXPORT_SYMBOL(drm_connector_update_privacy_screen); +/** + * drm_connector_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_connector_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_connector_hdmi_compute_mode_clock); + int drm_connector_set_obj_prop(struct drm_mode_object *obj, struct drm_property *property, uint64_t value) { int ret = -EINVAL; diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h index 29883e6f8e50..a859ad7ee04b 100644 --- a/include/drm/drm_connector.h +++ b/include/drm/drm_connector.h @@ -36,10 +36,11 @@ struct drm_connector_helper_funcs; struct drm_modeset_acquire_ctx; struct drm_device; struct drm_crtc; +struct drm_display_mode; struct drm_encoder; struct drm_panel; struct drm_property; struct drm_property_blob; struct drm_printer; @@ -2092,10 +2093,14 @@ int drm_connector_attach_max_bpc_property(struct drm_connector *connector, void drm_connector_create_privacy_screen_properties(struct drm_connector *conn); void drm_connector_attach_privacy_screen_properties(struct drm_connector *conn); void drm_connector_attach_privacy_screen_provider( struct drm_connector *connector, struct drm_privacy_screen *priv); void drm_connector_update_privacy_screen(const struct drm_connector_state *connector_state); +unsigned long long +drm_connector_hdmi_compute_mode_clock(const struct drm_display_mode *mode, + unsigned int bpc, + enum hdmi_colorspace fmt); /** * struct drm_tile_group - Tile group metadata * @refcount: reference count * @dev: DRM device