From: dinghao.liu@zju.edu.cn
To: "quanyang.wang" <quanyang.wang@windriver.com>
Cc: "Michal Simek" <michal.simek@xilinx.com>,
kjlu@umn.edu,
"Amit Kumar Mahapatra" <amit.kumar-mahapatra@xilinx.com>,
"Mark Brown" <broonie@kernel.org>,
linux-spi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: Re: [PATCH] spi: spi-zynqmp-gqspi: Fix runtime PM imbalance in zynqmp_qspi_probe
Date: Fri, 9 Apr 2021 15:53:37 +0800 (GMT+08:00) [thread overview]
Message-ID: <2b385fb0.45344.178b59f4790.Coremail.dinghao.liu@zju.edu.cn> (raw)
In-Reply-To: <ef4555a6-1674-d9c0-6401-cdf43780a014@windriver.com>
> Hi Dinghao,
>
> On 4/8/21 6:33 PM, Michal Simek wrote:
> > ++
> >
> > On 4/8/21 11:25 AM, Dinghao Liu wrote:
> >> When platform_get_irq() fails, a pairing PM usage counter
> >> increment is needed to keep the counter balanced. It's the
> >> same for the following error paths.
> >>
> >> Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
> >> ---
> >> drivers/spi/spi-zynqmp-gqspi.c | 1 +
> >> 1 file changed, 1 insertion(+)
> >>
> >> diff --git a/drivers/spi/spi-zynqmp-gqspi.c b/drivers/spi/spi-zynqmp-gqspi.c
> >> index c8fa6ee18ae7..95963a2de64a 100644
> >> --- a/drivers/spi/spi-zynqmp-gqspi.c
> >> +++ b/drivers/spi/spi-zynqmp-gqspi.c
> >> @@ -1197,6 +1197,7 @@ static int zynqmp_qspi_probe(struct platform_device *pdev)
> >> return 0;
> >>
> >> clk_dis_all:
> >> + pm_runtime_get_noresume(&pdev->dev);
> >> pm_runtime_set_suspended(&pdev->dev);
> >> pm_runtime_disable(&pdev->dev);
> >> clk_disable_unprepare(xqspi->refclk);
> >>
> The imbalance is because pm_runtime_put_autosuspend is called to make
> counter to be -1.
>
> It looks strange that there is no counter increament op before
> pm_runtime_put_autosuspend.
>
> In my limited understanding, it should look like:
>
> ......
>
> pm_runtime_enable
>
> pm_runtime_get_sync //increase counter to one to resume device
>
> DO OPERATIONS HERE
>
> pm_runtime_mark_last_busy
> pm_runtime_put_autosuspend //decrease counter to zero and trigger suspend
>
> return 0;
>
> error_path:
>
> pm_runtime_put_sync
>
> pm_runtime_disable
>
> return err;
>
>
> Am I missing something?
>
Thanks for point out this! Usually there is an increment refcount in a
_probe function and a decrement refcount in a _remove function. Sometimes
the refcount decrement is in the _probe and the increment is in the _remove.
But the refcount is balanced in both cases. So I think zynqmp_qspi_remove()
needs a refcount increment to fix this bug.
Regards,
Dinghao
next prev parent reply other threads:[~2021-04-09 7:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-08 9:25 [PATCH] spi: spi-zynqmp-gqspi: Fix runtime PM imbalance in zynqmp_qspi_probe Dinghao Liu
2021-04-08 10:33 ` Michal Simek
2021-04-09 1:33 ` quanyang.wang
2021-04-09 7:53 ` dinghao.liu [this message]
2021-04-08 16:54 ` Mark Brown
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