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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id B2EECC44508 for ; Wed, 15 Jul 2026 13:39:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=jmrADRp41+XuE1YAS0+fxI6szw8WHlVw1TFrAUgC7qE=; b=JLVQK3TnTXgeaJmlfs46J10LdV bMDDRDLu5BPNOedXjXfF1geVz83TDjr5JzfxNZtvdWqJtBkP3Oqf67i6pst7Zi1mycbZwEm+sPLj+ hhHfnh0jQ+A6SV/XaK7Gj6NG8TX9MkBnWW7Ejt6/0sk5EmyDjWYTR4dkUZrV2BUG1TthfleM5VUtY SnMf1HHmJQPW2Mst7EPgBmB3fxM2onFaFIq+8uDQnTJf+Yxf7TWxb87xapuwfg5jMsS2l/qsuHhg8 9eCyuIJcuWFEuLlPPmhNYVH+ihM5Bxs/t6yzefCVh6/03t4s89RL2ic9O/xwKcenxIA4rNjFuXew5 JK4CDgUw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wjzpx-0000000Ey8l-1B3I; Wed, 15 Jul 2026 13:39:45 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wjzpu-0000000Ey8A-26SG for linux-arm-kernel@lists.infradead.org; Wed, 15 Jul 2026 13:39:43 +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 6F2DC1477; Wed, 15 Jul 2026 06:39:37 -0700 (PDT) Received: from [10.2.212.8] (e134344.arm.com [10.2.212.8]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0DC5F3F915; Wed, 15 Jul 2026 06:39:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1784122781; bh=Wf9M5WQzRLOO4AudW1ZFMCjPLzlhRxKffT+HUe3T+8o=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Vs/1b9wDq7B/BM3pUJmgSa2Yweux6p0ygpwWDLYME3Uh0URWG4zmRwnbKJKppI4qq I+k2Bo2IpBdFVqi1V2FA7WfkWXUmknEAdOny+9vBF73bYoYPMxVf3cB9ukAiVR/4Sy cf9PhBGlcILhtf07rRkVJsL/nrEuEgCpJ3piL+uA= Message-ID: Date: Wed, 15 Jul 2026 14:39:37 +0100 MIME-Version: 1.0 User-Agent: Thunderbird Daily Subject: Re: [PATCH v3 07/16] arm_mpam: __ris_msmon_read(): get rid of nrdy special handling To: Andre Przywara , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Catalin Marinas , Will Deacon , "Rafael J . Wysocki" , Len Brown , James Morse , Reinette Chatre , Fenghua Yu Cc: Jonathan Cameron , Srivathsa L Rao , Ganapatrao Kulkarni , Trilok Soni , Srinivas Ramana , Niyas Sait , linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20260710144520.917375-1-andre.przywara@arm.com> <20260710144520.917375-8-andre.przywara@arm.com> Content-Language: en-US From: Ben Horgan In-Reply-To: <20260710144520.917375-8-andre.przywara@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260715_063942_628416_86DB07A0 X-CRM114-Status: GOOD ( 23.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Andre, On 7/10/26 15:45, Andre Przywara wrote: > Although so far MSC accesses couldn't fail, there is one special > condition that would create an error: when the MBWU counter wouldn't be > able to read a stable value, we were setting bit 63 to mark this value > as unstable, and return this as an error later. > Now since the functions can return a proper error value, we can get rid of > this kludge and use the return value directly. > > Remove the "nrdy" error flag variable, and assign -EBUSY to "ret" to handle > this case. I don't think we want this patch. The h/w can still return (as much as it ever could) and so we still need to handle it even if we are no longer augmenting its meaning in software to also indicate an unstable 64 bit value. Thanks, Ben > > Signed-off-by: Andre Przywara > --- > drivers/resctrl/mpam_devices.c | 38 +++++++++++++++------------------- > 1 file changed, 17 insertions(+), 21 deletions(-) > > diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c > index 84a8715464be..530ac0fe97b5 100644 > --- a/drivers/resctrl/mpam_devices.c > +++ b/drivers/resctrl/mpam_devices.c > @@ -1306,7 +1306,6 @@ static void __ris_msmon_read(void *arg) > u64 now; > int ret; > u32 now32; > - bool nrdy = false; > bool config_mismatch; > bool overflow = false; > struct mon_read *m = arg; > @@ -1371,14 +1370,18 @@ static void __ris_msmon_read(void *arg) > switch (m->type) { > case mpam_feat_msmon_csu: > ret = mpam_read_monsel_reg(msc, CSU, &now32); > + if (!ret) { > + if ((now32 & MSMON___NRDY)) > + ret = -EBUSY; > + > + if (mpam_has_quirk(IGNORE_CSU_NRDY, msc) && > + m->waited_timeout) > + ret = 0; > + } > if (ret) > goto out_unlock; > - nrdy = now32 & MSMON___NRDY; > - now = FIELD_GET(MSMON___VALUE, now32); > - > - if (mpam_has_quirk(IGNORE_CSU_NRDY, msc) && m->waited_timeout) > - nrdy = false; > > + now = FIELD_GET(MSMON___VALUE, now32); > break; > case mpam_feat_msmon_mbwu_31counter: > case mpam_feat_msmon_mbwu_44counter: > @@ -1394,9 +1397,11 @@ static void __ris_msmon_read(void *arg) > now = FIELD_GET(MSMON___L_VALUE, now); > } else { > ret = mpam_read_monsel_reg(msc, MBWU, &now32); > + if (!ret && (now32 & MSMON___NRDY)) > + ret = -EBUSY; > if (ret) > goto out_unlock; > - nrdy = now32 & MSMON___NRDY; > + > now = FIELD_GET(MSMON___VALUE, now32); > } > > @@ -1404,9 +1409,6 @@ static void __ris_msmon_read(void *arg) > m->type != mpam_feat_msmon_mbwu_63counter) > now *= 64; > > - if (nrdy) > - break; > - > mbwu_state = &ris->mbwu_state[ctx->mon]; > > if (overflow) > @@ -1419,22 +1421,16 @@ static void __ris_msmon_read(void *arg) > now += mbwu_state->correction; > break; > default: > - m->err = -EINVAL; > + ret = -EINVAL; > } > - mpam_mon_sel_unlock(msc); > - > - if (nrdy) > - m->err = -EBUSY; > - > - if (!m->err) > - *m->val += now; > - > - return; > > out_unlock: > mpam_mon_sel_unlock(msc); > > - m->err = ret; > + if (ret) > + m->err = ret; > + else > + *m->val += now; > } > > static int _msmon_read(struct mpam_component *comp, struct mon_read *arg)