From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7FF822F362B; Tue, 17 Mar 2026 17:23:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773768199; cv=none; b=d7aP61xWnQOUJFVR5dZJMfff1qkUvk+7+hSK/XnePMDP7QAllGeVWxctKtYEKPsU969XIJKVFhrABcpWNxkmsIpEFMxY/+rXAs5sGSafzMErXb/TFJ0ukfpMpFH7PKxFSH1kHD3LSK5Lsyv4+VCqCXZXgNS1iZLXRSy4ghj14Qk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773768199; c=relaxed/simple; bh=ungHzVpcs12NyM9sWoC4UOCJX24gnATKzZqw+b8d3NU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pZxgD2LMIOhA8cHc/vy5tq8yN44pyM3Av7K07yn5mNr0Xx3uFJuzWZHkREpcc6JnJa8SZ6EmVySGup8ulTOcLLWFHMdgrTmr5wXEgwDfL1f9GK7o1en/jeXbxfscU/+Uw7A0PIWDD7Qbp7zP8ry4gPcez7w5/H7ss/c7lknVX0c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=F6ynPNPi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="F6ynPNPi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6748C19424; Tue, 17 Mar 2026 17:23:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1773768199; bh=ungHzVpcs12NyM9sWoC4UOCJX24gnATKzZqw+b8d3NU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F6ynPNPiLdvgQmJ3VOJuETxKnW7/iYVg4ovuqvD9iRysCjm9CvjufY2Dfdkrt5Yjn VrtkhAkRgAng+c9Dve8RGipbbA2pviDsy5GFMKMnhCU5dHaQCUEOKAP4a8JoubD4Zm lhDZ7Z1vZkZtwvcn451NsCpVhXbBbEi+U74b5UlY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Marek Vasut , Luca Ceresoli Subject: [PATCH 6.18 255/333] drm/bridge: ti-sn65dsi83: halve horizontal syncs for dual LVDS output Date: Tue, 17 Mar 2026 17:34:44 +0100 Message-ID: <20260317163008.824481426@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260317162959.345812316@linuxfoundation.org> References: <20260317162959.345812316@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luca Ceresoli commit d0d727746944096a6681dc6adb5f123fc5aa018d upstream. Dual LVDS output (available on the SN65DSI84) requires HSYNC_PULSE_WIDTH and HORIZONTAL_BACK_PORCH to be divided by two with respect to the values used for single LVDS output. While not clearly stated in the datasheet, this is needed according to the DSI Tuner [0] output. It also makes sense intuitively because in dual LVDS output two pixels at a time are output and so the output clock is half of the pixel clock. Some dual-LVDS panels refuse to show any picture without this fix. Divide by two HORIZONTAL_FRONT_PORCH too, even though this register is used only for test pattern generation which is not currently implemented by this driver. [0] https://www.ti.com/tool/DSI-TUNER Fixes: ceb515ba29ba ("drm/bridge: ti-sn65dsi83: Add TI SN65DSI83 and SN65DSI84 driver") Cc: stable@vger.kernel.org Reviewed-by: Marek Vasut Link: https://patch.msgid.link/20260226-ti-sn65dsi83-dual-lvds-fixes-and-test-pattern-v1-2-2e15f5a9a6a0@bootlin.com Signed-off-by: Luca Ceresoli Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/bridge/ti-sn65dsi83.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c @@ -474,6 +474,7 @@ static void sn65dsi83_atomic_pre_enable( struct drm_atomic_state *state) { struct sn65dsi83 *ctx = bridge_to_sn65dsi83(bridge); + const unsigned int dual_factor = ctx->lvds_dual_link ? 2 : 1; const struct drm_bridge_state *bridge_state; const struct drm_crtc_state *crtc_state; const struct drm_display_mode *mode; @@ -606,18 +607,18 @@ static void sn65dsi83_atomic_pre_enable( /* 32 + 1 pixel clock to ensure proper operation */ le16val = cpu_to_le16(32 + 1); regmap_bulk_write(ctx->regmap, REG_VID_CHA_SYNC_DELAY_LOW, &le16val, 2); - le16val = cpu_to_le16(mode->hsync_end - mode->hsync_start); + le16val = cpu_to_le16((mode->hsync_end - mode->hsync_start) / dual_factor); regmap_bulk_write(ctx->regmap, REG_VID_CHA_HSYNC_PULSE_WIDTH_LOW, &le16val, 2); le16val = cpu_to_le16(mode->vsync_end - mode->vsync_start); regmap_bulk_write(ctx->regmap, REG_VID_CHA_VSYNC_PULSE_WIDTH_LOW, &le16val, 2); regmap_write(ctx->regmap, REG_VID_CHA_HORIZONTAL_BACK_PORCH, - mode->htotal - mode->hsync_end); + (mode->htotal - mode->hsync_end) / dual_factor); regmap_write(ctx->regmap, REG_VID_CHA_VERTICAL_BACK_PORCH, mode->vtotal - mode->vsync_end); regmap_write(ctx->regmap, REG_VID_CHA_HORIZONTAL_FRONT_PORCH, - mode->hsync_start - mode->hdisplay); + (mode->hsync_start - mode->hdisplay) / dual_factor); regmap_write(ctx->regmap, REG_VID_CHA_VERTICAL_FRONT_PORCH, mode->vsync_start - mode->vdisplay); regmap_write(ctx->regmap, REG_VID_CHA_TEST_PATTERN, 0x00);