Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754061AbdGCMzf (ORCPT ); Mon, 3 Jul 2017 08:55:35 -0400 Received: from foss.arm.com ([217.140.101.70]:33510 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752533AbdGCMzc (ORCPT ); Mon, 3 Jul 2017 08:55:32 -0400 Cc: Sudeep Holla , Jassi Brar , LKML , Alexey Klimov Subject: Re: [PATCH 1/2] mailbox: reset txdone_method TXDONE_BY_POLL if client knows_txdone To: Jassi Brar References: <1498835681-23975-1-git-send-email-sudeep.holla@arm.com> <3c542b86-4de1-3c97-5e2d-1335115ac9a3@arm.com> From: Sudeep Holla Organization: ARM Message-ID: <00dbf13b-d59c-d3b7-6185-a0d7e6ab60db@arm.com> Date: Mon, 3 Jul 2017 13:55:29 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3037 Lines: 84 On 03/07/17 12:50, Jassi Brar wrote: > On 3 July 2017 at 15:05, Sudeep Holla wrote: >> >> >> On 03/07/17 09:57, Sudeep Holla wrote: >>> >>> >>> On 01/07/17 12:25, Jassi Brar wrote: >>>> On Fri, Jun 30, 2017 at 8:44 PM, Sudeep Holla wrote: >>>>> Currently the mailbox framework sets txdone_method to TXDONE_BY_POLL if >>>>> the controller sets txdone_by_poll. However some clients can have a >>>>> mechanism to do TXDONE_BY_ACK which they can specify by knows_txdone. >>>>> However, we endup setting both TXDONE_BY_POLL and TXDONE_BY_ACK in that >>>>> case. In such scenario, we may end up with below warnings as the tx >>>>> ticker is run both by mailbox framework and the client. >>>>> >>>>> WARNING: CPU: 1 PID: 0 at kernel/time/hrtimer.c:805 hrtimer_forward+0x88/0xd8 >>>>> CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.12.0-rc5 #242 >>>>> Hardware name: ARM LTD ARM Juno Development Platform >>>>> task: ffff8009768ca700 task.stack: ffff8009768f8000 >>>>> PC is at hrtimer_forward+0x88/0xd8 >>>>> LR is at txdone_hrtimer+0xd4/0xf8 >>>>> Call trace: >>>>> hrtimer_forward+0x88/0xd8 >>>>> __hrtimer_run_queues+0xe4/0x158 >>>>> hrtimer_interrupt+0xa4/0x220 >>>>> arch_timer_handler_phys+0x30/0x40 >>>>> handle_percpu_devid_irq+0x78/0x130 >>>>> generic_handle_irq+0x24/0x38 >>>>> __handle_domain_irq+0x5c/0xb8 >>>>> gic_handle_irq+0x54/0xa8 >>>>> >>>>> This patch fixes the issue by resetting TXDONE_BY_POLL if client has set >>>>> knows_txdone. >>>>> >>>>> Cc: Alexey Klimov >>>>> Cc: Jassi Brar >>>>> Signed-off-by: Sudeep Holla >>>>> --- >>>>> drivers/mailbox/mailbox.c | 2 +- >>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>> >>>>> diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c >>>>> index 537f4f6d009b..8da30f833262 100644 >>>>> --- a/drivers/mailbox/mailbox.c >>>>> +++ b/drivers/mailbox/mailbox.c >>>>> @@ -351,7 +351,7 @@ struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index) >>>>> init_completion(&chan->tx_complete); >>>>> >>>>> if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone) >>>>> - chan->txdone_method |= TXDONE_BY_ACK; >>>>> + chan->txdone_method = TXDONE_BY_ACK; >>>>> >>>> It has to be restored back in mbox_free_channel() >>> >>> Ah right, will fix and repost. >>> >> >> I was too fast to response, I see we already take care of that in free >> channel. So I think it should be fine as is. >> >> if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK)) >> chan->txdone_method = TXDONE_BY_POLL; >> > You were too fast this time :) > Indeed, my understanding was correct before. > chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK) > > is not same as > > (chan->txdone_method == TXDONE_BY_POLL || chan->txdone_method == TXDONE_BY_ACK) > Ah crap, yes and I have no idea why I thought so when I was about to change it :( -- Regards, Sudeep