From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752823AbaCYLdK (ORCPT ); Tue, 25 Mar 2014 07:33:10 -0400 Received: from mailout2.w1.samsung.com ([210.118.77.12]:38542 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751158AbaCYLdI (ORCPT ); Tue, 25 Mar 2014 07:33:08 -0400 X-AuditID: cbfec7f5-b7fc96d000004885-77-533169719aa5 Message-id: <53316966.90600@samsung.com> Date: Tue, 25 Mar 2014 12:32:54 +0100 From: Tomasz Figa Organization: Samsung R&D Institute Poland User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-version: 1.0 To: Krzysztof Kozlowski , Daniel Lezcano , Thomas Gleixner , Kukjin Kim , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org Cc: Kyungmin Park , Marek Szyprowski , Bartlomiej Zolnierkiewicz Subject: Re: [PATCH] clocksource: exynos_mct: Fix stall after CPU hotplugging References: <1395744087-8655-1-git-send-email-k.kozlowski@samsung.com> In-reply-to: <1395744087-8655-1-git-send-email-k.kozlowski@samsung.com> Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrBLMWRmVeSWpSXmKPExsVy+t/xq7qFmYbBBp0dlhYbZ6xntZj3Wdbi 9QtDi94FV9kszja9YbfY9Pgaq8XlXXPYLGac38dksfbIXXaLzZumMjtwedy5tofN4925c+we m5fUe/RtWcXo8XmTXABrFJdNSmpOZllqkb5dAlfGlM9T2Qu+8Vf8XNLH3MB4haeLkZNDQsBE YkfjOkYIW0ziwr31bF2MXBxCAksZJTZtfM8I4XxmlFj5YDoTSBWvgIbE9gfzmUFsFgFVic6W TWDdbAJqEp8bHrGB2PwCWhJrmq6zgNiiAhES9xoPs0L0Ckr8mHyPBWSoiMA0JonlNz6AOcwC UxglmictBdsgLOArsW35FrCpQgJuEivmbAbbxingLvHq4mKwDcwC1hIrJ21jhLDlJTavecs8 gVFwFpIls5CUzUJStoCReRWjaGppckFxUnqukV5xYm5xaV66XnJ+7iZGSGx83cG49JjVIUYB DkYlHt4NpgbBQqyJZcWVuYcYJTiYlUR4DcMMg4V4UxIrq1KL8uOLSnNSiw8xMnFwSjUwTrnL wC3zNXmSzUdrlc5pP7ccUjs4Yw3vByXXD9evvPbt/u7dsd25vqzqyc7neXcmbGO7d0fl4d+j EVdbvvYr224JEVQO+yan8dzOel3qx5NbzwYprcoIEqi/bLFf22e+mpZZROSl04Zus2Uf6KUv OnmQh8MwXP3V/8C5cf/TpBJnvo+xe+nmqsRSnJFoqMVcVJwIAJKNFUtrAgAA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Krzysztof, Two comments inline. On 25.03.2014 11:41, Krzysztof Kozlowski wrote: [snip] > diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c > index 48f76bc05da0..0b49b09dd1a9 100644 > --- a/drivers/clocksource/exynos_mct.c > +++ b/drivers/clocksource/exynos_mct.c > @@ -339,7 +339,14 @@ static void exynos4_mct_tick_start(unsigned long cycles, > static int exynos4_tick_set_next_event(unsigned long cycles, > struct clock_event_device *evt) > { > - struct mct_clock_event_device *mevt = this_cpu_ptr(&percpu_mct_tick); > + /* > + * In case of hotplugging non-boot CPU, the set_next_event could be > + * called on CPU0 by ISR before IRQ affinity is set to proper CPU. Hmm, is this a desired behavior? I guess this is a question for Thomas and Daniel. > + * Thus for accessing proper MCT Lx timer, 'per_cpu' for cpumask > + * in event must be used instead of 'this_cpu_ptr'. > + */ > + struct mct_clock_event_device *mevt = &per_cpu(percpu_mct_tick, > + cpumask_first(evt->cpumask)); > > exynos4_mct_tick_start(cycles, mevt); > > @@ -371,23 +378,13 @@ static inline void exynos4_tick_set_mode(enum clock_event_mode mode, > > static int exynos4_mct_tick_clear(struct mct_clock_event_device *mevt) > { > - struct clock_event_device *evt = &mevt->evt; > - > - /* > - * This is for supporting oneshot mode. > - * Mct would generate interrupt periodically > - * without explicit stopping. > - */ > - if (evt->mode != CLOCK_EVT_MODE_PERIODIC) > - exynos4_mct_tick_stop(mevt); > - > /* Clear the MCT tick interrupt */ > if (__raw_readl(reg_base + mevt->base + MCT_L_INT_CSTAT_OFFSET) & 1) { > exynos4_mct_write(0x1, mevt->base + MCT_L_INT_CSTAT_OFFSET); > return 1; > - } else { > - return 0; > } > + > + return 0; Nobody seems to be checking return value of this function (and I don't see what it could be used for anyway), so I guess it could be simply made void. Best regards, Tomasz