{"id":2235181,"url":"http://patchwork.ozlabs.org/api/1.2/covers/2235181/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-ide/cover/20260508193240.176735-4-cassel@kernel.org/","project":{"id":13,"url":"http://patchwork.ozlabs.org/api/1.2/projects/13/?format=json","name":"Linux IDE development","link_name":"linux-ide","list_id":"linux-ide.vger.kernel.org","list_email":"linux-ide@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null,"list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260508193240.176735-4-cassel@kernel.org>","list_archive_url":null,"date":"2026-05-08T19:32:40","name":"[v2,0/2] ata: fix deferred QC handling for port multipliers","submitter":{"id":87751,"url":"http://patchwork.ozlabs.org/api/1.2/people/87751/?format=json","name":"Niklas Cassel","email":"cassel@kernel.org"},"mbox":"http://patchwork.ozlabs.org/project/linux-ide/cover/20260508193240.176735-4-cassel@kernel.org/mbox/","series":[{"id":503436,"url":"http://patchwork.ozlabs.org/api/1.2/series/503436/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-ide/list/?series=503436","date":"2026-05-08T19:32:41","name":"ata: fix deferred QC handling for port multipliers","version":2,"mbox":"http://patchwork.ozlabs.org/series/503436/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/covers/2235181/comments/","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linux-ide@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=KwFynRPq;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=2600:3c15:e001:75::12fc:5321; helo=sin.lore.kernel.org;\n envelope-from=linux-ide+bounces-5697-incoming=patchwork.ozlabs.org@vger.kernel.org;\n receiver=patchwork.ozlabs.org)","smtp.subspace.kernel.org;\n\tdkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org\n header.b=\"KwFynRPq\"","smtp.subspace.kernel.org;\n arc=none smtp.client-ip=10.30.226.201"],"Received":["from sin.lore.kernel.org (sin.lore.kernel.org\n [IPv6:2600:3c15:e001:75::12fc:5321])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4gBzpb0KGjz1yK7\n\tfor ; Sat, 09 May 2026 05:34:47 +1000 (AEST)","from smtp.subspace.kernel.org (conduit.subspace.kernel.org\n [100.90.174.1])\n\tby sin.lore.kernel.org (Postfix) with ESMTP id 63C3930377C0\n\tfor ; Fri, 8 May 2026 19:33:06 +0000 (UTC)","from localhost.localdomain (localhost.localdomain [127.0.0.1])\n\tby smtp.subspace.kernel.org (Postfix) with ESMTP id 67149359A8B;\n\tFri, 8 May 2026 19:32:59 +0000 (UTC)","from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org\n [10.30.226.201])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby smtp.subspace.kernel.org (Postfix) with ESMTPS id 43B6E284662\n\tfor ; Fri, 8 May 2026 19:32:59 +0000 (UTC)","by smtp.kernel.org (Postfix) with ESMTPSA id BF875C2BCB0;\n\tFri, 8 May 2026 19:32:57 +0000 (UTC)"],"ARC-Seal":"i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116;\n\tt=1778268779; cv=none;\n b=FRAaG9/A0auBOk1apoRY+DL5CnukdGQh4OhaOHnD/Xz3U3vljpedjEd5TKzFg1h2XkLXZLzv+HFNQnRI29nfgA+FssxMJLLLqt3hM8vFc4o75EaKYiH8KPrjNlrDXfEdC2qdvSDfIuFgiXQNyzaJEkvZ4FesQxPuh66q24BQwRk=","ARC-Message-Signature":"i=1; a=rsa-sha256; d=subspace.kernel.org;\n\ts=arc-20240116; t=1778268779; c=relaxed/simple;\n\tbh=ChDGXEmlBWdk7aNqrsHjo2rw2rZmfJDfEqJv/ZCe0vo=;\n\th=From:To:Cc:Subject:Date:Message-ID:MIME-Version;\n b=VQfPI3TzYx/Mf/JtXbxNfia9/DLtJH8riP4f08S4wLxbZk8oWTOU6XEDodZ8uzbxqqjUFael5mMdG/5XBHo9QA5ZKFWRW1ABL2f/e1H0KontL2fUiASvY434W2nWtJx70TKMniqLhK2BHyMRNXYLoZvQ4yiVjW3aVPDxpN7L7Hc=","ARC-Authentication-Results":"i=1; smtp.subspace.kernel.org;\n dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org\n header.b=KwFynRPq; arc=none smtp.client-ip=10.30.226.201","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;\n\ts=k20201202; t=1778268779;\n\tbh=ChDGXEmlBWdk7aNqrsHjo2rw2rZmfJDfEqJv/ZCe0vo=;\n\th=From:To:Cc:Subject:Date:From;\n\tb=KwFynRPqool5Q3CQBvUqZiXbPM5lDqFVYoZT2Z4G39WaMrofoeKeiOfL/oMgeQs++\n\t Xril4AjsgZgZxoRZMe5R7/7zKFQt0fE8fC+iia54dAhsBVRQh5ZUEQ0qjhZwlsK7zN\n\t WPkhgq09R5uK3aX8bajN4awAzsH3rGhDPDZnscfrNeEesgF+3RtnkgW1UFzAayANhD\n\t bwKPVXsJiiVrM4p5LX8d3rZ2q/52Hxgf5yClB2UEovWhKIZ59fN7bn5pxjDOvIPTh7\n\t 9T4VuftRtjBAC6G9QZhvxIXqJDtLLkyMANu8DPQxPM9Bsan+Ia4tKsmwBVxr0c7FBc\n\t 7zotWAU3s+fSw==","From":"Niklas Cassel ","To":"Tommy Kelly ,\n\tDamien Le Moal ,\n\tNiklas Cassel ,\n\t\"Martin K. Petersen\" ,\n\tJohn Garry ","Cc":"linux-ide@vger.kernel.org","Subject":"[PATCH v2 0/2] ata: fix deferred QC handling for port multipliers","Date":"Fri, 8 May 2026 21:32:40 +0200","Message-ID":"<20260508193240.176735-4-cassel@kernel.org>","X-Mailer":"git-send-email 2.54.0","Precedence":"bulk","X-Mailing-List":"linux-ide@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","X-Developer-Signature":"v=1; a=openpgp-sha256; l=1572; i=cassel@kernel.org;\n h=from:subject; bh=ChDGXEmlBWdk7aNqrsHjo2rw2rZmfJDfEqJv/ZCe0vo=;\n b=owGbwMvMwCV2MsVw8cxjvkWMp9WSGDL/WUX0TVJ4831ihseucLWv+oczl36RrNpd9XpdZ+7Un\n xONz9Ze7yhlYRDjYpAVU2Tx/eGyv7jbfcpxxTs2MHNYmUCGMHBxCsBE8mYx/E/fpV5Qvux52PPn\n fzPar37+6SAnxjd3Ykak2fv9J51uCMxi+Gd85lqFZH74Hc3tcQeKTA/I+LfNspq86JFwU1/AWcm\n oVi4A","X-Developer-Key":"i=cassel@kernel.org; a=openpgp;\n fpr=5ADE635C0E631CBBD5BE065A352FE6582ED9B5DA","Content-Transfer-Encoding":"8bit"},"content":"Hello all,\n\nTommy Kelly reported a regression with PMP that use CBS:\nhttps://lore.kernel.org/linux-ide/ce09cc21-a8e9-4845-b205-35411e22fba9@tkel.ly/\n\nIt turns out that the ap->excl_link logic used for PMP that use CBS is\nincompatible with the deferred qc issuing via a workqueue.\nThis is fixed in patch 1/2.\n\nWhile looking at the code, it turns out that the deferred qc issuing via\nworkqueue is misdesigned. It assumed that we can't mix NCQ and non-NCQ\ncommands on the same port. The limitation is that you can not mix NCQ and\nnon-NCQ commands on the same drive. However, with a PMP with FBS, you can\nissue (mixed NCQ and non-NCQ commands) to the different drives. Thus, move\nthe saved deferred QC from struct ata_port to struct ata_link. This is\nfixed in patch 2/2.\n\n\nChanges since v1:\n-As pointed out by Sashiko:\n https://sashiko.dev/#/patchset/20260501125410.1204490-5-cassel%40kernel.org?part=2\n My patch in v1 unintentionally changed the fairness of\n sata_pmp_qc_defer_cmd_switch().\n-Add a code comment which explains how the ap->excl_link handling works.\n\n\nNiklas Cassel (2):\n ata: libata-scsi: do not use the deferred QC feature on PMPs with CBS\n ata: libata-scsi: do not needlessly defer commands when using PMP with\n FBS\n\n drivers/ata/libata-core.c | 16 ++++---\n drivers/ata/libata-eh.c | 8 ++--\n drivers/ata/libata-pmp.c | 29 ++++++++++--\n drivers/ata/libata-scsi.c | 95 ++++++++++++++++++++++++---------------\n include/linux/libata.h | 8 ++--\n 5 files changed, 104 insertions(+), 52 deletions(-)"}