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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_NONE, 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 AC23EC433DF for ; Fri, 22 May 2020 12:18:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 83CDC207CB for ; Fri, 22 May 2020 12:18:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590149904; bh=39Z2YC/hT0DLTH/QrHnGkxDnIs+bUNDKpwlJ2UMsj60=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=n3B52OA+GyjpPH2KL8mr220T/1bqGe1+1L2pqOreGzQF1VwwvnJhUyZT1EeX4bxSy VpYjYN96MOE13L9733P043qyQqBDoSf83ZR4Hw0B+k58enS66qR3qvQAHMmtDqCmV/ wps+fdsroZ5LkVfagXHwGF3s1kBABMmBv5/kgNm4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728827AbgEVMSY (ORCPT ); Fri, 22 May 2020 08:18:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:57526 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728475AbgEVMSX (ORCPT ); Fri, 22 May 2020 08:18:23 -0400 Received: from localhost (fw-tnat.cambridge.arm.com [217.140.96.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3D30E20756; Fri, 22 May 2020 12:18:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590149902; bh=39Z2YC/hT0DLTH/QrHnGkxDnIs+bUNDKpwlJ2UMsj60=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=u+Ft0HnjgAU98axSOB3qR/6xwnjzxBk9o9hYIlkj4SxFevAgTjyTLw4u6ckl1uXGB 21ZP/qJQZNoRyC9/9+CrklTJUFWQ7ec5qhc0FpBM0QwQcTZtAZtJsdYb/vMgdVWfgR 5JsYBJz38tYaVElZskAnfIKOkrIMKz3l+CoLbzK4= Date: Fri, 22 May 2020 13:18:20 +0100 From: Mark Brown To: Andy Shevchenko Cc: Serge Semin , Serge Semin , Linus Walleij , Vinod Koul , Feng Tang , Grant Likely , Alan Cox , Georgy Vlasov , Ramil Zaripov , Alexey Malahov , Thomas Bogendoerfer , Paul Burton , Ralf Baechle , Arnd Bergmann , Rob Herring , linux-mips@vger.kernel.org, devicetree@vger.kernel.org, Wan Ahmad Zainie , Thomas Gleixner , Jarkko Nikula , "wuxu.wu" , Clement Leger , Linus Walleij , linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 01/16] spi: dw: Add Tx/Rx finish wait methods to the MID DMA Message-ID: <20200522121820.GG5801@sirena.org.uk> References: <20200522000806.7381-1-Sergey.Semin@baikalelectronics.ru> <20200522000806.7381-2-Sergey.Semin@baikalelectronics.ru> <20200522111340.GX1634618@smile.fi.intel.com> <20200522115235.rt3ay7lveimrgooa@mobilestation> <20200522121221.GA1634618@smile.fi.intel.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="L+ofChggJdETEG3Y" Content-Disposition: inline In-Reply-To: <20200522121221.GA1634618@smile.fi.intel.com> X-Cookie: C for yourself. User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org --L+ofChggJdETEG3Y Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, May 22, 2020 at 03:12:21PM +0300, Andy Shevchenko wrote: > On Fri, May 22, 2020 at 02:52:35PM +0300, Serge Semin wrote: > > Please, see it's implementation. It does atomic delay when the delay value > > is less than 10us. But selectively gets to the usleep_range() if value is > > greater than that. > Oh, than it means we may do a very long busy loop here which is not good at > all. If we have 10Hz clock, it might take seconds of doing nothing! Realistically it seems unlikely that the clock will be even as slow as double digit kHz though, and if we do I'd not be surprised to see other problems kicking in. It's definitely good to handle such things if we can but so long as everything is OK for realistic use cases I'm not sure it should be a blocker. --L+ofChggJdETEG3Y Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl7HwwsACgkQJNaLcl1U h9DGbQf/aA5931PtrryL4ZW3uh64EHvrtq6HdmmV34g803DbZetKXoSdCysw7oSi MdgShpfA9AR9+XVi5XuNVRh9REKm7VB54za86BUEm25d/W1x4G9rQiN5IxBLgwjZ HUCMBgd+VG+ql4pm3PmtanE4K33rwAiMJf77Bdw+oKdqvQIdiXUzBkdsOCQ+pluZ fOCeS+8ZfmX4nrg8f1Y8d7t633H4eHNbGe+H08iAsfBIGRfb7nmkdopxm6UviMbt zOixF+I4sCyeiZAXY/5GeFc27QZyKc6qjd4LAPZIc3/kjIRg8d3CkjFYDDyw6Mgq arVmdO3FsjblhLk4QYlHmt/Lc1alSg== =H1CF -----END PGP SIGNATURE----- --L+ofChggJdETEG3Y--