From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7DF2C4332B for ; Fri, 20 Mar 2020 14:43:36 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A67D020732 for ; Fri, 20 Mar 2020 14:43:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="fRpsrzro" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A67D020732 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type:Cc: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: MIME-Version:References:In-Reply-To:Date:To:From:Subject:Message-ID:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=VaQJAksgUHgZnWYxb1yAyJECIrso4J4uQVyfhAWiNMw=; b=fRpsrzroanXqExrgbgwYdSeed CpwYBrOAWUY3GVf8vd+IAiJbYmy+U2SWVHHDKfpkYR+LWnHfEQYuVPZFpyyWT9t8nQ5a4OTkfGlKt zR67wSv+1ZLa6nv6XzXUVhLzxcvVpxn2cEq5amA2dBEO/R5d0XE2XJTra1Z7XdEIN1m8iTJTGz+mW Oga2ajD4tdSSWEZg98Mf9F9M1+3OZ9HZ9/HlJ/t40uJMF7n88ZvqbsJQGZRLxEcvh7JPlhAQy+9vo vIlhVIuGIKla5SlDwpwDaDlNsJ9wApl8+Q97zkqG9Q8n76/DWPo+Qucfw+/3l4O55McRwK0EJOVfc PvW6sACNA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jFIs1-0001ag-6G; Fri, 20 Mar 2020 14:43:33 +0000 Received: from mx2.suse.de ([195.135.220.15]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jFIrx-0001a4-Fy; Fri, 20 Mar 2020 14:43:31 +0000 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 69C2EAD32; Fri, 20 Mar 2020 14:43:27 +0000 (UTC) Message-ID: <2f198d1afe80e4a4c48703462d63bdb0858fb4a2.camel@suse.de> Subject: Re: [PATCH] ARM: dts: bcm283x: Use firmware PM driver for V3D From: Nicolas Saenz Julienne To: Dave Stevenson , Stefan Wahren Date: Fri, 20 Mar 2020 15:43:25 +0100 In-Reply-To: References: <20200303173217.3987-1-nsaenzjulienne@suse.de> <736f0c59-352b-03b2-f77f-bfc22171b3fb@i2se.com> <03fcb1e2bc7f3ff389b6dfbf3964e159a93ae835.camel@suse.de> <01ceb60e-a791-b6ca-352e-ad2e79f264e3@i2se.com> <9e685fce547d808f269e59e2290331e75c66f3e4.camel@suse.de> <90e92438-00df-520f-c8b1-2e2077934592@i2se.com> User-Agent: Evolution 3.34.4 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200320_074329_822506_D30B2962 X-CRM114-Status: GOOD ( 18.70 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eric Anholt , Florian Fainelli , linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Maxime Ripard Content-Type: multipart/mixed; boundary="===============5443663461911992541==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============5443663461911992541== Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-/tkxwxJi1mY/EDU3Qsgm" --=-/tkxwxJi1mY/EDU3Qsgm Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2020-03-16 at 13:57 +0000, Dave Stevenson wrote: > Hi Stefan and Nicolas >=20 > Checking the docs it does state the restriction that Eric quotes. >=20 > HDMI Core Clock (state machine clock) > Most of the HDMI logic operates on that clock. It > is asynchronous to system core clock and pixel > clock. Source for this clock can be chosen from > various PLLs in the chip. See CPR Manager for > details. >=20 > This clock is also used for clocking pixel valve > when HDMI peripheral is used. See Pixel Valve > for details.axi_clock >=3D hdmi_core_clock > 108% of > pixel_clock. >=20 >=20 > The default max pixel clock from the firmware side is 162MHz. >=20 > In the firmware source we have a comment > // HDMI state machine clock must be faster than pixel clock - > infinitessimally faster tested in simulation. > // Otherwise, exact value is unimportant - for HDMI operation. > // hdmi state machine clock now derived from PLLC_PER (typ > 500MHz, see relevant platform.c). > // > // However, CEC bit clock is derived from the HSM clock, and > the (programmable) CEC timing table > // is configured for a 40.00kHz CEC clock. > const unsigned margin =3D 1*1000*1000; > unsigned min_hsm_clock =3D margin + timings->pixel_freq; > const unsigned max_hsm_clock_for_cec =3D max(163682864, > hdmi_pixel_freq_limit); >=20 > unsigned hdmi_state_machine_clock =3D max_hsm_clock_for_cec; >=20 > So it adds 1MHz to the pixel clock for min_hsm_clock, but then doesn't > use the value. > Unless you do request a higher hdmi_pixel_freq_limit then the HSM is > running at the same 163.68MHz that Eric's driver hard codes, and our > max pixel clock is 162MHz. > Keeping it a fixed value makes sorting the divider for CEC easier. >=20 > Just adopting a 162MHz limit with a suitable comment is probably the > most sensible move here, and Maxime's patches can pick up the same > value. I agree with Dave. Moreover, this was initially introduced to fix resolution negotiations with= 4k devices, which use higher pixel clocks than HSM_CLOCK_FREQ. I've been revie= wing common HDMI resolutions and 1200p60 seems to be the one closer to RPi's HSM limitations (as far as widely used aspect ratios are concerned). So I can't image how setting a smaller than HSM_CLOCK_FREQ limit here is going to brea= k anything. That said I'm no expert in this area. Stefan, any opinions? Feel like sending a patch? :) Regards, Nicolas --=-/tkxwxJi1mY/EDU3Qsgm Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEErOkkGDHCg2EbPcGjlfZmHno8x/4FAl501o0ACgkQlfZmHno8 x/5X7gf8Dt1VwHhuwYsFMK0N+kIBlPJFPb020tJAsnrIkw664hu9Cll04EB4MOG9 EaG3b2Jo9QUseesoKUnxkOMvUk05CxuOhUvhpM3pz5g9cI0BDrqo4n35pEh6F0CV p/JQGMzrXznbciEzJVXP2Tyz1HtNeECyOnQwpCrQLuE5c6zd4v+bw3ydexf+0LmH IAluJa/u4x3u1jrs4i2VGn2kGT9bWT3q+Y9bBCCwjKkYZigCx6Ab92HZaKC+N+hI unHr/aTUSGwUx6qjmtt+WXdXLt+Z1X3PfPzn6g69yLGg9mX64asfQeGoeRQT8x6v 7qW0Lis2BzrEEv5ih1yUoILIWbx0sA== =N/Y7 -----END PGP SIGNATURE----- --=-/tkxwxJi1mY/EDU3Qsgm-- --===============5443663461911992541== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============5443663461911992541==--