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=-5.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 C09F1C388F7 for ; Mon, 9 Nov 2020 14:03:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 76E5F208FE for ; Mon, 9 Nov 2020 14:03:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604930631; bh=0qWoR1msH12ErNOfjXIHiUCH+yFjvnvefxpiB9RfPxg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=uccpinLV2p8dJ81D3YzDxUDvAru26ojwJwcIq54Lto7WIEL/3rI4YXg9VNC5s6Woh PEDs2VzUYTKicsuAw+wo2+lPtONIrhvpqldmAvl8AwhhxONo2oZt5ELfbl5lcJjoil UclYhK7V41Xa+i1atCSOYDb8fDIyGs3MO2YZ7PDc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730807AbgKIODu (ORCPT ); Mon, 9 Nov 2020 09:03:50 -0500 Received: from mail.kernel.org ([198.145.29.99]:46140 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730301AbgKIODu (ORCPT ); Mon, 9 Nov 2020 09:03:50 -0500 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 0A05920867; Mon, 9 Nov 2020 14:03:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604930629; bh=0qWoR1msH12ErNOfjXIHiUCH+yFjvnvefxpiB9RfPxg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=wRs15LHircWzvXOo5eAGcE1LTAtxbL4/0ZY88LI86gw7Ho0CwqdiuVsSEAQIGcUv1 9I95eKzIRan+x1t7Duk9Jp1J5q71sIvNo0ijBwWxGhLnAcqvNWBnm09ukjE8xqjK7x RUnP9miyPzSp53rkkKslalwQownd4flZ5FKmtZ60= Date: Mon, 9 Nov 2020 14:03:35 +0000 From: Mark Brown To: Damien Le Moal Cc: Palmer Dabbelt , linux-riscv@lists.infradead.org, Rob Herring , Frank Rowand , devicetree@vger.kernel.org, Serge Semin , linux-spi@vger.kernel.org, Stephen Boyd , linux-clk@vger.kernel.org, Linus Walleij , linux-gpio@vger.kernel.org, Philipp Zabel , Sean Anderson Subject: Re: [PATCH 05/32] spi: dw: Introduce DW_SPI_CAP_POLL_NODELAY Message-ID: <20201109140335.GC6380@sirena.org.uk> References: <20201107081420.60325-1-damien.lemoal@wdc.com> <20201107081420.60325-6-damien.lemoal@wdc.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="ZmUaFz6apKcXQszQ" Content-Disposition: inline In-Reply-To: <20201107081420.60325-6-damien.lemoal@wdc.com> X-Cookie: This fortune is false. User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org --ZmUaFz6apKcXQszQ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Sat, Nov 07, 2020 at 05:13:53PM +0900, Damien Le Moal wrote: > On slow systems, i.e. systems with a slow CPU resulting in slow context > switches, calling spi_delay_exec() when executing polled transfers > using dw_spi_poll_transfer() can lead to RX FIFO overflows. Allow > platforms to opt out of delayed polling by introducing the > DW_SPI_CAP_POLL_NODELAY DW SPI capability flag to disable > the execution of spi_delay_exec() in dw_spi_poll_transfer(). This feels like it should be done based on something like a cutoff for sufficiently small delays rather than with a capability - it's tuning, not a property of the system. --ZmUaFz6apKcXQszQ Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl+pTDcACgkQJNaLcl1U h9ANcwf/YmBAqrHq0UScXKCySZxkuvWStVH14/YdQZtvZPP/q+momYYX4pc3kd/c TBpsNlmcayA1zutuPZnLrGDvbvZveMzTmNelO1tPR3Of2cCvVzxsg7ll9McnW0tO lQH/+nQTFzmRa2VmkMwf4qOSjkmBmtTZxn7tEJeuXLHNzNXWuChhNxTaDe8nVW16 YgDEFpyJP4apsxGFPAbFEgvPmbdz38L0VIlKE7779QjJ+s2l2npzVFpB9kVAPYX0 InWN9ZugvH0NFUo1vP2s6Ap57nSDtx2uNiY8YC+Q2O9tJYEp8ayKAFvh2pMQaq1k s9tHGmXcudhAm0qR5VH22WaH1cXUTw== =zXja -----END PGP SIGNATURE----- --ZmUaFz6apKcXQszQ--