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[2620:137:e000::1:20]) by mx.google.com with ESMTP id 123-20020a630481000000b0041bee410f48si1077828pge.551.2022.08.04.04.42.17; Thu, 04 Aug 2022 04:42:32 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@raspberrypi.com header.s=google header.b=iXLRL5Vm; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=raspberrypi.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236833AbiHDLbW (ORCPT + 99 others); Thu, 4 Aug 2022 07:31:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42678 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231375AbiHDLbV (ORCPT ); Thu, 4 Aug 2022 07:31:21 -0400 Received: from mail-ed1-x52b.google.com (mail-ed1-x52b.google.com [IPv6:2a00:1450:4864:20::52b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 49DA532DAB for ; Thu, 4 Aug 2022 04:31:19 -0700 (PDT) Received: by mail-ed1-x52b.google.com with SMTP id b96so14625615edf.0 for ; Thu, 04 Aug 2022 04:31:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=raspberrypi.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=OZCMUxfbvhV8KUF7AQQe3QbS9+vNWbCElynU3LR9VS4=; b=iXLRL5Vm95CI/aiauBsLd6V9ZtUPLX/NJy6pPlAWa63XnDQ1oALPg0Atx2OmS+T9ff tA1MdiuOx3RVaDyTQDz4AMqZp5EsmK0QRLCbpXXaLovQdmjY3oJKTZTMC4LUQVRMyauh T3wC3dKYWV/6wwYwxF8TeVSGMgeCUCGZ1ffcyiB7LFTm/T1irGOAJbJJGOqE6OWl0SNM 0mLzl9jRmeaXDAmAK7DsmwqdtKaWcgngvTKrm8aykT80GFGBCVCf86QXBKfRjTov+wRz cjCwEU1SoxYzeA8nCxVDSAQMtzgtcKaSx8Q34mE+gBcWgDiKAMpm7oW8jBGIQ0R1zikC plwg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=OZCMUxfbvhV8KUF7AQQe3QbS9+vNWbCElynU3LR9VS4=; b=RaSYIeNGZVd9jlA8YUEZ4GnuaMwtcLlHz/02e0gUROZ9zxTfeSYx+TVtk94XWWkQNw VkiVpHEnk9atBecQEuWRH0ING6qKdLVQOzurAjMpYvYGJzEo9282v9IFEUGOrepDqr3Q iyb+rmajre9YVijBWe5amSB2HCD9W4W7I3M36WcWkZAihm5BYLJLsarGy7nXX9jAIFeD HbfNK4UD1OEo5/Cz6ADCl7IN1LOQ2wuMbVayCFlIIasTfDmuqWQqzKmifKBtYVvhFXXD SiUHwU8WEMuojwIJ6ZSeeVIhkBfO/ym9EjWZkjvJ7MSvjTcGgomZ1Nyw0PBpnIdjiv1+ +lxA== X-Gm-Message-State: ACgBeo1pkrv7MlZWo8k81zstSi6IgS2Nh+x/ZRWbwJC4AhjM1sSI9lFr d/sK9p4+E3HsBIrDsahcJlEH/ldSphhXPnIFv+tt+g== X-Received: by 2002:a05:6402:1771:b0:43d:3fab:dd73 with SMTP id da17-20020a056402177100b0043d3fabdd73mr1596394edb.136.1659612677847; Thu, 04 Aug 2022 04:31:17 -0700 (PDT) MIME-Version: 1.0 References: <20220802080820.jyf3tfpgcj3pvbtp@pengutronix.de> <20220803062024.vn7awasmifkp5xow@pengutronix.de> <20220804093829.42kdelp7u4r743nv@pengutronix.de> In-Reply-To: <20220804093829.42kdelp7u4r743nv@pengutronix.de> From: Dave Stevenson Date: Thu, 4 Aug 2022 12:31:01 +0100 Message-ID: Subject: Re: imx8mm lcdif->dsi->adv7535 no video, no errors To: Marco Felsch Cc: Adam Ford , Neil Armstrong , David Airlie , dri-devel , Laurent Pinchart , Andrzej Hajda , Marek Szyprowski , Marek Vasut , Jernej Skrabec , Jagan Teki , robert.chiras@nxp.com, laurentiu.palcu@nxp.com, NXP Linux Team , Jonas Karlman , Sascha Hauer , arm-soc , Linux Kernel Mailing List , Robert Foss , Pengutronix Kernel Team , Shawn Guo Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marco On Thu, 4 Aug 2022 at 10:38, Marco Felsch wrote: > > Hi Dave, Adam, > > On 22-08-03, Dave Stevenson wrote: > > Hi Adam > > > > On Wed, 3 Aug 2022 at 12:03, Adam Ford wrote: > > ... > > > > > Did managed to get access to the ADV7535 programming guide? This is the > > > > black box here. Let me check if I can provide you a link with our repo > > > > so you can test our current DSIM state if you want. > > > > > > I do have access to the programming guide, but it's under NDA, but > > > I'll try to answer questions if I can. > > > > Not meaning to butt in, but I have datasheets for ADV7533 and 7535 > > from previously looking at these chips. > > Thanks for stepping into :) > > > Mine fairly plainly states: > > "The DSI receiver input supports DSI video mode operation only, and > > specifically, only supports nonburst mode with sync pulses". > > I've read this also, and we are working in nonburst mode with sync > pulses. I have no access to an MIPI-DSI analyzer therefore I can't > verify it. > > > Non-burst mode meaning that the DSI pixel rate MUST be the same as the > > HDMI pixel rate. > > On DSI side you don't have a pixel-clock instead there is bit-clock. You have an effective pixel clock, with a fixed conversion for the configuration. DSI bit-clock * number of lanes / bits_per_pixel = pixel rate. 891Mbit/s * 4 lanes / 24bpp = 148.5 Mpixels/s As noted elsewhere, the DSI is DDR, so the clock lane itself is only running at 891 / 2 = 445.5MHz. > > Section 6.1.1 "DSI Input Modes" of adv7533_hardware_user_s_guide is > > even more explicit about the requirement of DSI timing matching > > Is it possible to share the key points of the requirements? "Specifically the ADV7533 supports the Non-Burst Mode with syncs. This mode requires real time data generation as a pulse packet received becomes a pulse generated. Therefore this mode requires a continuous stream of data with correct video timing to avoid any visual artifacts." LP mode is supported on data lanes. Clock lane must remain in HS mode. "... the goal is to accurately convey DPI-type timing over DSI. This includes matching DPI pixel-transmission rates, and widths of timing events." > > The NXP kernel switching down to an hs_clk of 445.5MHz would therefore > > be correct for 720p operation. > > It should be absolute no difference if you work on 891MHz with 2 lanes > or on 445.5 MHz with 4 lanes. What must be ensured is that you need the > minimum required bandwidth which is roughly: 1280*720*24*60 = 1.327 > GBps. Has someone changed the number of lanes in use? I'd missed that if so, but I'll agree that 891MHz over 2 lanes should work for 720p60. I have just noted that 720p59.94 at 24bpp on 4 lanes is listed as one of the modes that is mandatory to use the timing generator (reg 0x27 bit 7 = 1). On 2 lanes it is not required. I don't know why it's referencing the 1000/1001 pixel clock rates and not the base one, as it's only a base clock change with the same timing (74.176MHz clock instead of 74.25MHz). > > If you do program the manual DSI divider register to allow a DSI pixel > > rate of 148.5MHz vs HDMI pixel rate of 74.25MHz, you'd be relying on > > There is no such DSI pixel rate to be precise, we only have a DSI bit > clock/rate. > > > the ADV753x having at least a half-line FIFO between DSI rx and HDMI > > tx to compensate for the differing data rates. I see no reference to > > such, and I'd be surprised if it was more than a half dozen pixels to > > compensate for the jitter in the cases where the internal timing > > generator is mandatory due to fractional bytes. > > This is interesting and would proofs our assumption that the device > don't have a FIFO :) > > Our assumptions (we don't have the datasheet/programming manual): > - HDMI part is fetching 3 bytes per HDMI pixclk > - Ratio between dsi-clk and hdmi-pixelclk must be 3 so the DSI and > HDMI are in sync. So from bandwidth pov there are no differences > between: > - HDMI: 74.25 MHz * 24 Bit = 1782.0 MBit/s > - DSI: 891 MHz * 2 lanes = 1782.0 MBit/s (dsi-clock: 445.5 ) > - DSI: 445.5 MHz * 4 lanes = 1782.0 MBit/s (dsi-clock: 222.75) > > But the ratio is different and therefore the faster clocking option > let something 'overflow'. I'll agree that all looks consistent. > Anyway, but all this means that Adam should configure the > burst-clock-rate to 445.5 and set the lanes to 4. But this doesn't work > either and now we are back on my initial statement -> the driver needs > some attention. Things always need attention :-) I suspect that it's the use of the timing generator that is the issue. The programming guide does recommend using it for all modes, so that would be a sensible first step. I will say that we had a number of issues getting this chip to do anything, and it generally seemed happier on 2 or 3 lanes instead of 4. Suffice to say that we abandoned trying to use it, despite some assistance from ADI. Dave