linux-kernel - Re: [PATCH v3 1/1] spi: spi-cadence-quadspi: Fix pm runtime unbalance

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Message-ID: <62b9964d-0f2c-4d26-9b35-bb7af3aa5c4f@suswa.mountain>
Date: Fri, 27 Jun 2025 07:39:24 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: khairul.anuar.romli@...era.com
Cc: Mark Brown <broonie@...nel.org>,
	"open list:SPI SUBSYSTEM" <linux-spi@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>,
	Matthew Gerlach <matthew.gerlach@...era.com>,
	Khairul Anuar Romli <khairulanuar.romli@...era.com>
Subject: Re: [PATCH v3 1/1] spi: spi-cadence-quadspi: Fix pm runtime unbalance

On Thu, Jun 26, 2025 at 11:37:53PM -0500, Dan Carpenter wrote:
> On Mon, Jun 16, 2025 at 09:13:53AM +0800, khairul.anuar.romli@...era.com wrote:
> > From: Khairul Anuar Romli <khairul.anuar.romli@...era.com>
> > 
> > Having PM put sync in remove function is causing PM underflow during
> > remove operation. This is caused by the function, runtime_pm_get_sync,
> > not being called anywhere during the op. Ensure that calls to
> > pm_runtime_enable()/pm_runtime_disable() and
> > pm_runtime_get_sync()/pm_runtime_put_sync() match.
> > 
> > echo 108d2000.spi > /sys/bus/platform/drivers/cadence-qspi/unbind
> > [   49.644256] Deleting MTD partitions on "108d2000.spi.0":
> > [   49.649575] Deleting u-boot MTD partition
> > [   49.684087] Deleting root MTD partition
> > [   49.724188] cadence-qspi 108d2000.spi: Runtime PM usage count underflow!
> > 
> > Continuous bind/unbind will result in an "Unbalanced pm_runtime_enable" error.
> > Subsequent unbind attempts will return a "No such device" error, while bind
> > attempts will return a "Resource temporarily unavailable" error.
> > 
> > [   47.592434] cadence-qspi 108d2000.spi: Runtime PM usage count underflow!
> > [   49.592233] cadence-qspi 108d2000.spi: detected FIFO depth (1024) different from config (128)
> > [   53.232309] cadence-qspi 108d2000.spi: Runtime PM usage count underflow!
> > [   55.828550] cadence-qspi 108d2000.spi: detected FIFO depth (1024) different from config (128)
> > [   57.940627] cadence-qspi 108d2000.spi: Runtime PM usage count underflow!
> > [   59.912490] cadence-qspi 108d2000.spi: detected FIFO depth (1024) different from config (128)
> > [   61.876243] cadence-qspi 108d2000.spi: Runtime PM usage count underflow!
> > [   61.883000] platform 108d2000.spi: Unbalanced pm_runtime_enable!
> > [  532.012270] cadence-qspi 108d2000.spi: probe with driver cadence-qspi failed1
> > 
> > Also, change clk_disable_unprepare() to clk_disable() since continuous
> > bind and unbind operations will trigger a warning indicating that the clock is
> > already unprepared.
> > 
> > Fixes: 4892b374c9b7 ("mtd: spi-nor: cadence-quadspi: Add runtime PM support")
> > cc: stable@...r.kernel.org # 6.6+
> > Signed-off-by: Khairul Anuar Romli <khairul.anuar.romli@...era.com>
> > Reviewed-by: Matthew Gerlach <matthew.gerlach@...era.com>
> > ---
> > Changes in v3:
> >     - v2 was sent without a "Changes in v2" section.
> > 
> > Changes in v2:
> >     - Remove the runtime_pm variable from the struct, as it’s not needed for the fix.
> > ---
> >  drivers/spi/spi-cadence-quadspi.c | 12 +++++++-----
> >  1 file changed, 7 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
> > index c90462783b3f..506a139fbd2c 100644
> > --- a/drivers/spi/spi-cadence-quadspi.c
> > +++ b/drivers/spi/spi-cadence-quadspi.c
> > @@ -1958,10 +1958,10 @@ static int cqspi_probe(struct platform_device *pdev)
> >  			goto probe_setup_failed;
> >  	}
> >  
> > -	ret = devm_pm_runtime_enable(dev);
> > -	if (ret) {
> > -		if (cqspi->rx_chan)
> > -			dma_release_channel(cqspi->rx_chan);
> > +	pm_runtime_enable(dev);
> > +
> > +	if (cqspi->rx_chan) {
> > +		dma_release_channel(cqspi->rx_chan);
> >  		goto probe_setup_failed;
> >  	}
> 
> This will totally break the driver.  It was supposed to be
> 
> 	if (ret) {
> 		if (cqspi->rx_chan)
> 			dma_release_channel(cqspi->rx_chan);
> 		goto probe_setup_failed;
>   	}
> 
> In other words, if we failed there was some slightly complicated
> cleanup to do.  But now it will do the cleanup and free things on the
> success path if we're in cqspi->use_direct_mode.
> 

I suck at email.  What I meant was delete the if block:

-	if (cqspi->rx_chan) {
-		dma_release_channel(cqspi->rx_chan);
-		goto probe_setup_failed;
-	}
-

regards,
dan carpenter