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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 2B345C282DD for ; Thu, 9 Jan 2020 14:14:51 +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 EEB5D2067D for ; Thu, 9 Jan 2020 14:14:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="YgQETHSm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EEB5D2067D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com 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: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ZKHHnwawQNkCEA5EqMOq0n7+RG9tCd5ZHDefT4qaE4E=; b=YgQETHSmXE/1ELJPjDgK6IIyd QhUxFMGHnXuFomI2DonmklkrwgE2rQeQTALzHwtRlcgGXWzsQ7XhSiqkR74D5+Sne2LYdc6fIp1UL BgFz5InbmS11jV0i1dnfkhUaGVbxmd3kl25rZrGC51nTvka4PJf1GqFGsxCev5ZdNWVO/0KDoJ01w O7WV7FYepgD29v1vLkyv71hCNJk7V0VVUb6zUA/K4mwj2UXJsUAvW5q/uHzIeewAQlMTeiLmRYBy+ WsGoYsBkz23VzA1pAAPi9z7U3f9HhK7zs4wX1k8Oa63Twyr+0eN8stAV8Lzg6XwtYW7PO9NGPL0U0 ud7OQSNqA==; 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 1ipYaI-0002H2-GB; Thu, 09 Jan 2020 14:14:50 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ipYaF-0002GH-HI; Thu, 09 Jan 2020 14:14:49 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D33C81FB; Thu, 9 Jan 2020 06:14:46 -0800 (PST) Received: from [10.1.27.38] (unknown [10.1.27.38]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 254C93F534; Thu, 9 Jan 2020 06:14:43 -0800 (PST) Subject: Re: [PATCH v2 4/7] drm/panfrost: Add support for a second regulator for the GPU To: Nicolas Boichat , Mark Brown References: <20200108052337.65916-1-drinkcat@chromium.org> <20200108052337.65916-5-drinkcat@chromium.org> <20200108132302.GA3817@sirena.org.uk> From: Steven Price Message-ID: <09ddfac3-da8d-c039-92a0-d0f51dc3fea5@arm.com> Date: Thu, 9 Jan 2020 14:14:42 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200109_061447_621180_4EE0ACB4 X-CRM114-Status: GOOD ( 20.56 ) 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: Mark Rutland , Devicetree List , Tomeu Vizoso , David Airlie , lkml , dri-devel@lists.freedesktop.org, Liam Girdwood , Rob Herring , "moderated list:ARM/Mediatek SoC support" , Alyssa Rosenzweig , Hsin-Yi Wang , Matthias Brugger , linux-arm Mailing List Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 08/01/2020 22:52, Nicolas Boichat wrote: > On Wed, Jan 8, 2020 at 9:23 PM Mark Brown wrote: >> >> On Wed, Jan 08, 2020 at 01:23:34PM +0800, Nicolas Boichat wrote: >> >>> Some GPUs, namely, the bifrost/g72 part on MT8183, have a second >>> regulator for their SRAM, let's add support for that. >> >>> + pfdev->regulator_sram = devm_regulator_get_optional(pfdev->dev, "sram"); >>> + if (IS_ERR(pfdev->regulator_sram)) { >> >> This supply is required for the devices that need it so I'd therefore >> expect the driver to request the supply non-optionally based on the >> compatible string rather than just hoping that a missing regulator isn't >> important. > > That'd be a bit awkward to match, though... Currently all bifrost > share the same compatible "arm,mali-bifrost", and it'd seem > weird/wrong to match "mediatek,mt8183-mali" in this driver? I have no > idea if any other Mali implementation will require a second regulator, > but with the MT8183 we do need it, see below. > >> Though I do have to wonder given the lack of any active >> management of the supply if this is *really* part of the GPU or if it's >> more of a SoC thing, it's not clear what exactly adding this code is >> achieving. > > Well if devfreq was working (see patch 7 > https://patchwork.kernel.org/patch/11322851/ for a partial > implementation), it would adjust both mali and sram regulators, see > the OPP table in patch 2 > (https://patchwork.kernel.org/patch/11322825/): SRAM voltage needs to > be increased for frequencies >=698Mhz. > > Now if you have some better idea how to implement this, I'm all ears! I'm not sure if it's better, but could we just encode the list of regulators into device tree. I'm a bit worried about special casing an "sram" regulator given that other platforms might have a similar situation but call the second regulator a different name. Steve > Thanks. > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel