linux-kernel - Re: [PATCH 1/2] mailbox: reset txdone_method TXDONE_BY_POLL if client knows

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Message-ID: <3c542b86-4de1-3c97-5e2d-1335115ac9a3@arm.com>
Date:   Mon, 3 Jul 2017 09:57:56 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Jassi Brar <jassisinghbrar@...il.com>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Alexey Klimov <alexey.klimov@....com>,
        Jassi Brar <jaswinder.singh@...aro.org>
Subject: Re: [PATCH 1/2] mailbox: reset txdone_method TXDONE_BY_POLL if client
 knows_txdone



On 01/07/17 12:25, Jassi Brar wrote:
> On Fri, Jun 30, 2017 at 8:44 PM, Sudeep Holla <sudeep.holla@....com> 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 <alexey.klimov@....com>
>> Cc: Jassi Brar <jaswinder.singh@...aro.org>
>> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
>> ---
>>  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.

-- 
Regards,
Sudeep