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=-3.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 B4F3FC433DF for ; Thu, 20 Aug 2020 10:49:22 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 8256220724 for ; Thu, 20 Aug 2020 10:49:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="sOQ07rF3"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="Jz6FCIM9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8256220724 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=samsung.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.20170209; h=Sender:Content-Type:Cc: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: References:MIME-Version:Message-ID:In-Reply-To:Date:Subject:To:From: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=YL9eUSkXpy/MA4qEaDFGamE5HtlNo2lEeIgr3kHSffk=; b=sOQ07rF3yIiesI1yAG2GdGcVM Zk98gkQ0qUjKlgIWwCodyrXYKfHaK3er9b8SrGY7SIS6tWeBtPUrwjzTTur21SG0KnqQiF1CeGccb IBxMwd/LyfInz3YINjMMWJWHr6IrPdhroCaSY2W5b0HjylyWIeom1xzF3jgccoNiBZ+dnuT8u45JG Ny/0JQ3XCGmpVC+NCZ1FTxa3umxLPDkdq1vQRpkhdnRQIYqtgb9/rmXNbkrs0zAfDn2n5Jf6LjvUs B1VdVDPX0MrjpK22n4XGZwedC4cssGnOrQuM4I3lx5AXjkcxRMx2J7R7ED9eZdn0jYc6d101c8UeC usYvOK5cQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k8i6g-0007bD-5L; Thu, 20 Aug 2020 10:47:42 +0000 Received: from mailout2.w1.samsung.com ([210.118.77.12]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k8i6d-0007af-GW for linux-arm-kernel@lists.infradead.org; Thu, 20 Aug 2020 10:47:40 +0000 Received: from eucas1p2.samsung.com (unknown [182.198.249.207]) by mailout2.w1.samsung.com (KnoxPortal) with ESMTP id 20200820104737euoutp024167e954dbac73b66a38f16b8f9bcaf2~s9DCwhMMZ0602806028euoutp02n; Thu, 20 Aug 2020 10:47:37 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout2.w1.samsung.com 20200820104737euoutp024167e954dbac73b66a38f16b8f9bcaf2~s9DCwhMMZ0602806028euoutp02n DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1597920457; bh=7WJ9ipRlkuaJUk4o4grQFz2PxaIdJoQh60sHhV0DFT4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Jz6FCIM9l9v5yrnVaHYzsAfNR1PLrwbB56fpFAovrgwit935SydBZbUeiM/N1lO/L PbIiKFEX7fqvxux7t/lW7K3C0I2hDGFu2u1eegyHH8kMQx+Tnlr9Q5xPa3h3bPsjq7 rolhTjQvkY+0mv9oiHJQkaNoohdSBmr/mY60/s4k= Received: from eusmges3new.samsung.com (unknown [203.254.199.245]) by eucas1p1.samsung.com (KnoxPortal) with ESMTP id 20200820104737eucas1p112881b83eab752b80042953a38074886~s9DCbEQ3b0275402754eucas1p11; Thu, 20 Aug 2020 10:47:37 +0000 (GMT) Received: from eucas1p1.samsung.com ( [182.198.249.206]) by eusmges3new.samsung.com (EUCPMTA) with SMTP id 32.CD.06318.9C45E3F5; Thu, 20 Aug 2020 11:47:37 +0100 (BST) Received: from eusmtrp1.samsung.com (unknown [182.198.249.138]) by eucas1p1.samsung.com (KnoxPortal) with ESMTPA id 20200820104737eucas1p140e3c575eb692a1de54c5a702951ebfe~s9DCGoE9e1948319483eucas1p1B; Thu, 20 Aug 2020 10:47:37 +0000 (GMT) Received: from eusmgms2.samsung.com (unknown [182.198.249.180]) by eusmtrp1.samsung.com (KnoxPortal) with ESMTP id 20200820104737eusmtrp1b8657180ba1a19d55ba927dcfeb41838~s9DCGAWmc2448524485eusmtrp1y; Thu, 20 Aug 2020 10:47:37 +0000 (GMT) X-AuditID: cbfec7f5-38bff700000018ae-a8-5f3e54c98637 Received: from eusmtip1.samsung.com ( [203.254.199.221]) by eusmgms2.samsung.com (EUCPMTA) with SMTP id B8.77.06017.8C45E3F5; Thu, 20 Aug 2020 11:47:36 +0100 (BST) Received: from localhost (unknown [106.120.51.46]) by eusmtip1.samsung.com (KnoxPortal) with ESMTPA id 20200820104736eusmtip1ebfd77e5ae922d9acda4cc440279da19~s9DB51x7W2890228902eusmtip1R; Thu, 20 Aug 2020 10:47:36 +0000 (GMT) From: Lukasz Stelmach To: Mark Brown Subject: Re: [PATCH 2/8] spi: spi-s3s64xx: Add S3C64XX_SPI_QUIRK_CS_AUTO for Exynos3250 Date: Thu, 20 Aug 2020 12:47:26 +0200 In-Reply-To: <20200819193816.GB38371@sirena.org.uk> (Mark Brown's message of "Wed, 19 Aug 2020 20:38:16 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrPKsWRmVeSWpSXmKPExsWy7djPc7onQ+ziDf6uErdY/OM5k8XGGetZ LaY+fMJm0f/4NbPF+fMb2C02Pb7GanF51xw2ixnn9zFZNH68yW6x9shddgcuj+tLPjF7bFrV yeaxeUm9R9+WVYwenzfJBbBGcdmkpOZklqUW6dslcGX8nn+OqWCBWMWaV8+ZGhjPCnUxcnJI CJhIHFm5lq2LkYtDSGAFo8Sk9bNYIZwvjBLbN3UzQTifGSXm/jkL5HCAtSzuK4aIL2eUaN10 kglklJDAc0aJR9PlQWrYBPQk1q6NAAmLCChLXP2+lwWknllgDZPE7IdrGUESwgKREreXT2AB sVkEVCXOrtjPDmJzChRKzD51FszmFTCXWHliH1iNqIClxJYX96HighInZz4BizML5ErMPP+G EWSBhMAtdol1fz6zQvzmInF11QsoW1ji1fEt7BC2jMTpyT0sEM/US0yeZAbR28MosW3ODxaI GmuJO+d+sUHYjhK/Dz5ig6jnk7jxVhBiL5/EpG3TmSHCvBIdbdAQVZFY178HaoqURO+rFYwQ JR4S7XOgwdbGKLF172S2CYwKs5B8MwvJN7OAWpgFNCXW79KHCGtLLFv4mhnCtpVYt+49ywJG 1lWM4qmlxbnpqcXGeanlesWJucWleel6yfm5mxiBSev0v+NfdzDu+5N0iFGAg1GJhzdAyTZe iDWxrLgy9xCjCtCkRxtWX2CUYsnLz0tVEuF1Ons6Tog3JbGyKrUoP76oNCe1+BCjNAeLkjiv 8aKXsUIC6YklqdmpqQWpRTBZJg5OqQbGzQ7/WEpX7pBq23hX9GyCUTJ3zLEzpocv3509q/nX 6Xn/ni/6LWFY9G6qI5/nv04H78gztucctlqxz7ike8B3uTjfSqFp2RvdY/cEVHy59KIu68Ci H4v0qlyDpHKuGBc59rpapB0ItfSdJVP28dQtgy2/s4olTlWuPZvjverHc0WtuVt87N7+VWIp zkg01GIuKk4EANNLIrViAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrOIsWRmVeSWpSXmKPExsVy+t/xu7onQuziDXYesLZY/OM5k8XGGetZ LaY+fMJm0f/4NbPF+fMb2C02Pb7GanF51xw2ixnn9zFZNH68yW6x9shddgcuj+tLPjF7bFrV yeaxeUm9R9+WVYwenzfJBbBG6dkU5ZeWpCpk5BeX2CpFG1oY6RlaWugZmVjqGRqbx1oZmSrp 29mkpOZklqUW6dsl6GX8nn+OqWCBWMWaV8+ZGhjPCnUxcnBICJhILO4r7mLk4hASWMoocbHj BxNEXEpi5dz0LkZOIFNY4s+1LjaImqeMEiuXrmIBqWET0JNYuzYCpEZEQFni6ve9LCA2s8BS Jon3d11BbGGBcInfh1eBxYUEjCR+NvWwgtgsAqoSZ1fsZwexOQUKJWafOgtm8wqYS6w8sQ+s XlTAUmLLi/tQcUGJkzOfQM3Plvi6+jnzBEaBWUhSs5CkZgFdxyygKbF+lz5EWFti2cLXzBC2 rcS6de9ZFjCyrmIUSS0tzk3PLTbSK07MLS7NS9dLzs/dxAiMuG3Hfm7Zwdj1LvgQowAHoxIP b4CSbbwQa2JZcWXuIUYVoDGPNqy+wCjFkpefl6okwut09nScEG9KYmVValF+fFFpTmrxIUZT oD8nMkuJJucDk0ReSbyhqaG5haWhubG5sZmFkjhvh8DBGCGB9MSS1OzU1ILUIpg+Jg5OqQZG t7ZFNTKPbP1eCFqLCMtH8/Ql5srMLpohwZQ0361OeM3ZSaX9vCZ7g6UfemT5Xt6+7FTSMVWp h+c+f2pnN36eZeztdXt7Y9X86wcO9qw5p2FaXvmo5mnbe5OZhuUTZG4JGTfvCnFM13C+zmS0 PixOQk5iyxb/T/omCwt4p+uGRxUKH3IquqLEUpyRaKjFXFScCAAKbWWM2gIAAA== X-CMS-MailID: 20200820104737eucas1p140e3c575eb692a1de54c5a702951ebfe X-Msg-Generator: CA X-RootMTR: 20200820104737eucas1p140e3c575eb692a1de54c5a702951ebfe X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20200820104737eucas1p140e3c575eb692a1de54c5a702951ebfe References: <20200819193816.GB38371@sirena.org.uk> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200820_064739_737781_AAA2C45A X-CRM114-Status: GOOD ( 26.66 ) 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: linux-samsung-soc@vger.kernel.org, b.zolnierkie@samsung.com, linux-kernel@vger.kernel.org, Krzysztof Kozlowski , linux-spi@vger.kernel.org, Kukjin Kim , Andi Shyti , linux-arm-kernel@lists.infradead.org, m.szyprowski@samsung.com Content-Type: multipart/mixed; boundary="===============7248647063251637647==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============7248647063251637647== Content-Type: multipart/signed; boundary="=-=-="; micalg="pgp-sha256"; protocol="application/pgp-signature" --=-=-= Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable It was <2020-08-19 =C5=9Bro 20:38>, when Mark Brown wrote: > On Wed, Aug 19, 2020 at 03:01:21PM +0200, Lukasz Stelmach wrote: >> It was <2020-08-19 =C5=9Bro 14:39>, when Krzysztof Kozlowski wrote: > >>> There is here no commit msg, no explanation. > >> As I wrote in the cover letter, this and previous commits make things >> work on Exynos3250 (ARTIK5 precisely). I can't explain why. I read >> everything I could about this HW and there were no details about >> automatic CS handling other than how to turn it on and off. > > What is similar about those other SoCs - could you be more specific > here, or what goes wrong if you don't set this? Without the quirk set DMA transfers longer than 512 bytes fail. They simply stop and hit the timeout with a few (<20) bytes pending. As far as I can tell the SPI controller is the same in different Exynos SoCs. > The auto mode (or at least the auto mode that was on the Exynos7) is > not compatible with many SPI devices if the controller chip select is > actually in use, the quirk was added for controllers that just don't > have the manual mode. According to the manual the auto mode makes the controller toggle CS between SPI packets (bytes?). I=C2=A0didn't have any problem transferring data (>512 bytes) from the SPI device in the polling mode. Only the DMA caused problems. > See also: > > https://lore.kernel.org/linux-spi/CAAgF-BfGwcNzMx0meFVkJqNMTbQ4_PP1PZ3i= 6edOm6U3bc26_Q@mail.gmail.com/ > > for an explanation of the quirk. > >> CS can also be controlled automatically by setting AUTO_N_MANUAL to 1 >> in CS_CFG. When it is auto CS automatically toggles between packet to >> packet. NCS_TIME_COUNT in CS_CFG controls the inactive period. The >> driver by default uses manual mode. But on exynos7 the manual mode is >> removed. I *suspect* that the automatic CS toggling between packets gives better (?) synchronisation between the SPI device and the controller's internals and prevents some kind of a deadlock inside the controller. These are just speculations. =2D-=20 =C5=81ukasz Stelmach Samsung R&D Institute Poland Samsung Electronics --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEXpuyqjq9kGEVr9UQsK4enJilgBAFAl8+VL4ACgkQsK4enJil gBCobwf+LjO7fiQ+cGZHf8IsqYN/VyXQSsG+kaaGX4m/CYUMGTVs1GZpTWJnAZvM vCJgkQvHZZN5gWgkKmeH9Bkj91Frzv2zXlW304h2Vg9V5suiF58Xuqi3ynnecAhk QsYFb1c7X2LCvFhgpCAu0y39iODVafDIFAomUc+7HDRAFHy5rN8od+3HTzd/U46x s0AnNvJUt/diwApiv9aCpyJphgfMu2I+NXJdfMaFvs5Npp1rtlWGq+U5Z11Yc2VD UW657sr6135wlHEQPbcCOr7rB5D2Utwq8eM2zciOA5iIumidEpkR5g2GtWDgZM5V RZIWmtKeVCI4bKveBkkPEvxqpEhJdw== =aDU8 -----END PGP SIGNATURE----- --=-=-=-- --===============7248647063251637647== 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 --===============7248647063251637647==--