diff mbox series

[4/7] iio: adis16475: re-set max spi transfer

Message ID 20210413112105.69458-5-nuno.sa@analog.com (mailing list archive)
State New
Headers show
Series Adis IRQ fixes and minor improvements | expand

Commit Message

Sa, Nuno April 13, 2021, 11:21 a.m. UTC
In case 'spi_sync()' fails, we would be left with a max spi transfer
which is not the one the user expects it to be. Hence, we need to re-set
it also in this error path.

Fixes: fff7352bf7a3c ("iio: imu: Add support for adis16475")
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
 drivers/iio/imu/adis16475.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Alexandru Ardelean April 14, 2021, 7:28 a.m. UTC | #1
On Tue, Apr 13, 2021 at 5:45 PM Nuno Sa <nuno.sa@analog.com> wrote:
>
> In case 'spi_sync()' fails, we would be left with a max spi transfer
> which is not the one the user expects it to be. Hence, we need to re-set
> it also in this error path.
>
> Fixes: fff7352bf7a3c ("iio: imu: Add support for adis16475")
> Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> ---
>  drivers/iio/imu/adis16475.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/imu/adis16475.c b/drivers/iio/imu/adis16475.c
> index 51b76444db0b..9dca7e506200 100644
> --- a/drivers/iio/imu/adis16475.c
> +++ b/drivers/iio/imu/adis16475.c
> @@ -1067,8 +1067,10 @@ static irqreturn_t adis16475_trigger_handler(int irq, void *p)
>         adis->spi->max_speed_hz = ADIS16475_BURST_MAX_SPEED;
>
>         ret = spi_sync(adis->spi, &adis->msg);

Purely stylistic here.
But, the restore from the cached variable could be done here in a single line.
So. just moving [1] here.

> -       if (ret)
> +       if (ret) {
> +               adis->spi->max_speed_hz = cached_spi_speed_hz;
>                 goto check_burst32;
> +       }
>
>         adis->spi->max_speed_hz = cached_spi_speed_hz;
[1]

>         buffer = adis->buffer;
> --
> 2.31.1
>
Sa, Nuno April 15, 2021, 7:53 a.m. UTC | #2
> -----Original Message-----
> From: Alexandru Ardelean <ardeleanalex@gmail.com>
> Sent: Wednesday, April 14, 2021 9:29 AM
> To: Sa, Nuno <Nuno.Sa@analog.com>
> Cc: linux-iio <linux-iio@vger.kernel.org>; Jonathan Cameron
> <jic23@kernel.org>; Hennerich, Michael
> <Michael.Hennerich@analog.com>; Lars-Peter Clausen
> <lars@metafoo.de>
> Subject: Re: [PATCH 4/7] iio: adis16475: re-set max spi transfer
> 
> [External]
> 
> On Tue, Apr 13, 2021 at 5:45 PM Nuno Sa <nuno.sa@analog.com>
> wrote:
> >
> > In case 'spi_sync()' fails, we would be left with a max spi transfer
> > which is not the one the user expects it to be. Hence, we need to re-
> set
> > it also in this error path.
> >
> > Fixes: fff7352bf7a3c ("iio: imu: Add support for adis16475")
> > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > ---
> >  drivers/iio/imu/adis16475.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iio/imu/adis16475.c b/drivers/iio/imu/adis16475.c
> > index 51b76444db0b..9dca7e506200 100644
> > --- a/drivers/iio/imu/adis16475.c
> > +++ b/drivers/iio/imu/adis16475.c
> > @@ -1067,8 +1067,10 @@ static irqreturn_t
> adis16475_trigger_handler(int irq, void *p)
> >         adis->spi->max_speed_hz = ADIS16475_BURST_MAX_SPEED;
> >
> >         ret = spi_sync(adis->spi, &adis->msg);
> 
> Purely stylistic here.
> But, the restore from the cached variable could be done here in a
> single line.
> So. just moving [1] here.

You mean also doing it in the label? I thought about that and the reason
why I didn't is that on a normal run, I want to reset the max freq as soon
as possible so that if someone concurrently tries to read 'direct mode' attrs
gets the max freq. This was my reasoning but I admit that it's not that
important so I will leave this to Jonathan's preference...

Hmm now that I spoke about the concurrently access to IIO attr and being paranoid about
the compiler, I wonder if we should not use
WRITE_ONCE(adis->spi->max_speed_hz, ADIS16475_BURST_MAX_SPEED)...
Sa, Nuno April 15, 2021, 8:16 a.m. UTC | #3
> -----Original Message-----
> From: Sa, Nuno <Nuno.Sa@analog.com>
> Sent: Thursday, April 15, 2021 9:54 AM
> To: Alexandru Ardelean <ardeleanalex@gmail.com>
> Cc: linux-iio <linux-iio@vger.kernel.org>; Jonathan Cameron
> <jic23@kernel.org>; Hennerich, Michael
> <Michael.Hennerich@analog.com>; Lars-Peter Clausen
> <lars@metafoo.de>
> Subject: RE: [PATCH 4/7] iio: adis16475: re-set max spi transfer
> 
> [External]
> 
> 
> 
> > -----Original Message-----
> > From: Alexandru Ardelean <ardeleanalex@gmail.com>
> > Sent: Wednesday, April 14, 2021 9:29 AM
> > To: Sa, Nuno <Nuno.Sa@analog.com>
> > Cc: linux-iio <linux-iio@vger.kernel.org>; Jonathan Cameron
> > <jic23@kernel.org>; Hennerich, Michael
> > <Michael.Hennerich@analog.com>; Lars-Peter Clausen
> > <lars@metafoo.de>
> > Subject: Re: [PATCH 4/7] iio: adis16475: re-set max spi transfer
> >
> > [External]
> >
> > On Tue, Apr 13, 2021 at 5:45 PM Nuno Sa <nuno.sa@analog.com>
> > wrote:
> > >
> > > In case 'spi_sync()' fails, we would be left with a max spi transfer
> > > which is not the one the user expects it to be. Hence, we need to
> re-
> > set
> > > it also in this error path.
> > >
> > > Fixes: fff7352bf7a3c ("iio: imu: Add support for adis16475")
> > > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > > ---
> > >  drivers/iio/imu/adis16475.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/iio/imu/adis16475.c
> b/drivers/iio/imu/adis16475.c
> > > index 51b76444db0b..9dca7e506200 100644
> > > --- a/drivers/iio/imu/adis16475.c
> > > +++ b/drivers/iio/imu/adis16475.c
> > > @@ -1067,8 +1067,10 @@ static irqreturn_t
> > adis16475_trigger_handler(int irq, void *p)
> > >         adis->spi->max_speed_hz = ADIS16475_BURST_MAX_SPEED;
> > >
> > >         ret = spi_sync(adis->spi, &adis->msg);
> >
> > Purely stylistic here.
> > But, the restore from the cached variable could be done here in a
> > single line.
> > So. just moving [1] here.
> 
> You mean also doing it in the label? I thought about that and the
> reason
> why I didn't is that on a normal run, I want to reset the max freq as
> soon
> as possible so that if someone concurrently tries to read 'direct mode'
> attrs
> gets the max freq. This was my reasoning but I admit that it's not that
> important so I will leave this to Jonathan's preference...
> 
> Hmm now that I spoke about the concurrently access to IIO attr and
> being paranoid about
> the compiler, I wonder if we should not use
> WRITE_ONCE(adis->spi->max_speed_hz,
> ADIS16475_BURST_MAX_SPEED)...

Hmmm, actually WRITE_ONCE would not be any help since the spi core
does not use READ_ONCE. So, if we are going to be paranoid about the
compiler and load/store tearing, I guess the only safe way here is to
acquire the adis lock [btw, I'm a bit paranoid with this stuff :)]...

Anyways, arguably the likelihood for this to happen is really, really small...
Jonathan Cameron April 18, 2021, 10:20 a.m. UTC | #4
On Thu, 15 Apr 2021 08:16:30 +0000
"Sa, Nuno" <Nuno.Sa@analog.com> wrote:

> > -----Original Message-----
> > From: Sa, Nuno <Nuno.Sa@analog.com>
> > Sent: Thursday, April 15, 2021 9:54 AM
> > To: Alexandru Ardelean <ardeleanalex@gmail.com>
> > Cc: linux-iio <linux-iio@vger.kernel.org>; Jonathan Cameron
> > <jic23@kernel.org>; Hennerich, Michael
> > <Michael.Hennerich@analog.com>; Lars-Peter Clausen
> > <lars@metafoo.de>
> > Subject: RE: [PATCH 4/7] iio: adis16475: re-set max spi transfer
> > 
> > [External]
> > 
> > 
> >   
> > > -----Original Message-----
> > > From: Alexandru Ardelean <ardeleanalex@gmail.com>
> > > Sent: Wednesday, April 14, 2021 9:29 AM
> > > To: Sa, Nuno <Nuno.Sa@analog.com>
> > > Cc: linux-iio <linux-iio@vger.kernel.org>; Jonathan Cameron
> > > <jic23@kernel.org>; Hennerich, Michael
> > > <Michael.Hennerich@analog.com>; Lars-Peter Clausen
> > > <lars@metafoo.de>
> > > Subject: Re: [PATCH 4/7] iio: adis16475: re-set max spi transfer
> > >
> > > [External]
> > >
> > > On Tue, Apr 13, 2021 at 5:45 PM Nuno Sa <nuno.sa@analog.com>
> > > wrote:  
> > > >
> > > > In case 'spi_sync()' fails, we would be left with a max spi transfer
> > > > which is not the one the user expects it to be. Hence, we need to  
> > re-  
> > > set  
> > > > it also in this error path.
> > > >
> > > > Fixes: fff7352bf7a3c ("iio: imu: Add support for adis16475")
> > > > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > > > ---
> > > >  drivers/iio/imu/adis16475.c | 4 +++-
> > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/iio/imu/adis16475.c  
> > b/drivers/iio/imu/adis16475.c  
> > > > index 51b76444db0b..9dca7e506200 100644
> > > > --- a/drivers/iio/imu/adis16475.c
> > > > +++ b/drivers/iio/imu/adis16475.c
> > > > @@ -1067,8 +1067,10 @@ static irqreturn_t  
> > > adis16475_trigger_handler(int irq, void *p)  
> > > >         adis->spi->max_speed_hz = ADIS16475_BURST_MAX_SPEED;
> > > >
> > > >         ret = spi_sync(adis->spi, &adis->msg);  
> > >
> > > Purely stylistic here.
> > > But, the restore from the cached variable could be done here in a
> > > single line.
> > > So. just moving [1] here.  
> > 
> > You mean also doing it in the label? I thought about that and the
> > reason
> > why I didn't is that on a normal run, I want to reset the max freq as
> > soon
> > as possible so that if someone concurrently tries to read 'direct mode'
> > attrs
> > gets the max freq. This was my reasoning but I admit that it's not that
> > important so I will leave this to Jonathan's preference...
> > 
> > Hmm now that I spoke about the concurrently access to IIO attr and
> > being paranoid about
> > the compiler, I wonder if we should not use
> > WRITE_ONCE(adis->spi->max_speed_hz,
> > ADIS16475_BURST_MAX_SPEED)...  
> 
> Hmmm, actually WRITE_ONCE would not be any help since the spi core
> does not use READ_ONCE. So, if we are going to be paranoid about the
> compiler and load/store tearing, I guess the only safe way here is to
> acquire the adis lock [btw, I'm a bit paranoid with this stuff :)]...
> 
> Anyways, arguably the likelihood for this to happen is really, really small... 

Really small, but needs fixing.  We shouldn't have a window in which this
can happen.  So either we need to stop those attributes from reading whilst
we are in buffered mode (via claim_direct_mode pattern) or we need to put
a lock around this.  As an alternative, could we use the speed_hz field
in appropriate spi_transfer structures to tweak in this path without
affecting others?  That should make this concurrency problem an issue
for the spi core (which I'd assume handles this).

I'm going to hold this series for now on basis we should resolve this whilst
here.

Jonathan
Sa, Nuno April 19, 2021, 7:47 a.m. UTC | #5
> -----Original Message-----
> From: Jonathan Cameron <jic23@kernel.org>
> Sent: Sunday, April 18, 2021 12:21 PM
> To: Sa, Nuno <Nuno.Sa@analog.com>
> Cc: Alexandru Ardelean <ardeleanalex@gmail.com>; linux-iio <linux-
> iio@vger.kernel.org>; Hennerich, Michael
> <Michael.Hennerich@analog.com>; Lars-Peter Clausen
> <lars@metafoo.de>
> Subject: Re: [PATCH 4/7] iio: adis16475: re-set max spi transfer
> 
> [External]
> 
> On Thu, 15 Apr 2021 08:16:30 +0000
> "Sa, Nuno" <Nuno.Sa@analog.com> wrote:
> 
> > > -----Original Message-----
> > > From: Sa, Nuno <Nuno.Sa@analog.com>
> > > Sent: Thursday, April 15, 2021 9:54 AM
> > > To: Alexandru Ardelean <ardeleanalex@gmail.com>
> > > Cc: linux-iio <linux-iio@vger.kernel.org>; Jonathan Cameron
> > > <jic23@kernel.org>; Hennerich, Michael
> > > <Michael.Hennerich@analog.com>; Lars-Peter Clausen
> > > <lars@metafoo.de>
> > > Subject: RE: [PATCH 4/7] iio: adis16475: re-set max spi transfer
> > >
> > > [External]
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Alexandru Ardelean <ardeleanalex@gmail.com>
> > > > Sent: Wednesday, April 14, 2021 9:29 AM
> > > > To: Sa, Nuno <Nuno.Sa@analog.com>
> > > > Cc: linux-iio <linux-iio@vger.kernel.org>; Jonathan Cameron
> > > > <jic23@kernel.org>; Hennerich, Michael
> > > > <Michael.Hennerich@analog.com>; Lars-Peter Clausen
> > > > <lars@metafoo.de>
> > > > Subject: Re: [PATCH 4/7] iio: adis16475: re-set max spi transfer
> > > >
> > > > [External]
> > > >
> > > > On Tue, Apr 13, 2021 at 5:45 PM Nuno Sa <nuno.sa@analog.com>
> > > > wrote:
> > > > >
> > > > > In case 'spi_sync()' fails, we would be left with a max spi
> transfer
> > > > > which is not the one the user expects it to be. Hence, we need
> to
> > > re-
> > > > set
> > > > > it also in this error path.
> > > > >
> > > > > Fixes: fff7352bf7a3c ("iio: imu: Add support for adis16475")
> > > > > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > > > > ---
> > > > >  drivers/iio/imu/adis16475.c | 4 +++-
> > > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/iio/imu/adis16475.c
> > > b/drivers/iio/imu/adis16475.c
> > > > > index 51b76444db0b..9dca7e506200 100644
> > > > > --- a/drivers/iio/imu/adis16475.c
> > > > > +++ b/drivers/iio/imu/adis16475.c
> > > > > @@ -1067,8 +1067,10 @@ static irqreturn_t
> > > > adis16475_trigger_handler(int irq, void *p)
> > > > >         adis->spi->max_speed_hz =
> ADIS16475_BURST_MAX_SPEED;
> > > > >
> > > > >         ret = spi_sync(adis->spi, &adis->msg);
> > > >
> > > > Purely stylistic here.
> > > > But, the restore from the cached variable could be done here in a
> > > > single line.
> > > > So. just moving [1] here.
> > >
> > > You mean also doing it in the label? I thought about that and the
> > > reason
> > > why I didn't is that on a normal run, I want to reset the max freq as
> > > soon
> > > as possible so that if someone concurrently tries to read 'direct
> mode'
> > > attrs
> > > gets the max freq. This was my reasoning but I admit that it's not
> that
> > > important so I will leave this to Jonathan's preference...
> > >
> > > Hmm now that I spoke about the concurrently access to IIO attr
> and
> > > being paranoid about
> > > the compiler, I wonder if we should not use
> > > WRITE_ONCE(adis->spi->max_speed_hz,
> > > ADIS16475_BURST_MAX_SPEED)...
> >
> > Hmmm, actually WRITE_ONCE would not be any help since the spi
> core
> > does not use READ_ONCE. So, if we are going to be paranoid about
> the
> > compiler and load/store tearing, I guess the only safe way here is to
> > acquire the adis lock [btw, I'm a bit paranoid with this stuff :)]...
> >
> > Anyways, arguably the likelihood for this to happen is really, really
> small...
> 
> Really small, but needs fixing.  We shouldn't have a window in which
> this

Agreed!

> can happen.  So either we need to stop those attributes from reading
> whilst
> we are in buffered mode (via claim_direct_mode pattern) or we need
> to put
> a lock around this.  As an alternative, could we use the speed_hz field
> in appropriate spi_transfer structures to tweak in this path without
> affecting others?  That should make this concurrency problem an issue
> for the spi core (which I'd assume handles this).

Hmm, I like the 'speed_hz' approach as there's no reason to grab
the lock because of a spi core tweak. As you said, with this, we push things
to spi core. Going one step further, I think the most appropriate thing to do
is actually come up with a new member in the 'adis_data' struct
(like burst_max_speed_hz) and tweak the burst mode transfers accordingly in
'adis_update_scan_mode_burst()' (as there's no need to set this on every
burst sample)...

If we are going the above path, what would be your preference? To add the
patches to this series? Or to just fix this patch and [1] and push another series
with the above changes? Hmm, since [1] would also depend on this, I guess the
later approach would be better?

[1]: https://patchwork.kernel.org/project/linux-iio/patch/20210413092815.28626-1-nuno.sa@analog.com/

- Nuno Sá
Jonathan Cameron April 19, 2021, 3:41 p.m. UTC | #6
On Mon, 19 Apr 2021 07:47:55 +0000
"Sa, Nuno" <Nuno.Sa@analog.com> wrote:

> > -----Original Message-----
> > From: Jonathan Cameron <jic23@kernel.org>
> > Sent: Sunday, April 18, 2021 12:21 PM
> > To: Sa, Nuno <Nuno.Sa@analog.com>
> > Cc: Alexandru Ardelean <ardeleanalex@gmail.com>; linux-iio <linux-  
> > iio@vger.kernel.org>; Hennerich, Michael  
> > <Michael.Hennerich@analog.com>; Lars-Peter Clausen
> > <lars@metafoo.de>
> > Subject: Re: [PATCH 4/7] iio: adis16475: re-set max spi transfer
> > 
> > [External]
> > 
> > On Thu, 15 Apr 2021 08:16:30 +0000
> > "Sa, Nuno" <Nuno.Sa@analog.com> wrote:
> >   
> > > > -----Original Message-----
> > > > From: Sa, Nuno <Nuno.Sa@analog.com>
> > > > Sent: Thursday, April 15, 2021 9:54 AM
> > > > To: Alexandru Ardelean <ardeleanalex@gmail.com>
> > > > Cc: linux-iio <linux-iio@vger.kernel.org>; Jonathan Cameron
> > > > <jic23@kernel.org>; Hennerich, Michael
> > > > <Michael.Hennerich@analog.com>; Lars-Peter Clausen
> > > > <lars@metafoo.de>
> > > > Subject: RE: [PATCH 4/7] iio: adis16475: re-set max spi transfer
> > > >
> > > > [External]
> > > >
> > > >
> > > >  
> > > > > -----Original Message-----
> > > > > From: Alexandru Ardelean <ardeleanalex@gmail.com>
> > > > > Sent: Wednesday, April 14, 2021 9:29 AM
> > > > > To: Sa, Nuno <Nuno.Sa@analog.com>
> > > > > Cc: linux-iio <linux-iio@vger.kernel.org>; Jonathan Cameron
> > > > > <jic23@kernel.org>; Hennerich, Michael
> > > > > <Michael.Hennerich@analog.com>; Lars-Peter Clausen
> > > > > <lars@metafoo.de>
> > > > > Subject: Re: [PATCH 4/7] iio: adis16475: re-set max spi transfer
> > > > >
> > > > > [External]
> > > > >
> > > > > On Tue, Apr 13, 2021 at 5:45 PM Nuno Sa <nuno.sa@analog.com>
> > > > > wrote:  
> > > > > >
> > > > > > In case 'spi_sync()' fails, we would be left with a max spi  
> > transfer  
> > > > > > which is not the one the user expects it to be. Hence, we need  
> > to  
> > > > re-  
> > > > > set  
> > > > > > it also in this error path.
> > > > > >
> > > > > > Fixes: fff7352bf7a3c ("iio: imu: Add support for adis16475")
> > > > > > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > > > > > ---
> > > > > >  drivers/iio/imu/adis16475.c | 4 +++-
> > > > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > > > >
> > > > > > diff --git a/drivers/iio/imu/adis16475.c  
> > > > b/drivers/iio/imu/adis16475.c  
> > > > > > index 51b76444db0b..9dca7e506200 100644
> > > > > > --- a/drivers/iio/imu/adis16475.c
> > > > > > +++ b/drivers/iio/imu/adis16475.c
> > > > > > @@ -1067,8 +1067,10 @@ static irqreturn_t  
> > > > > adis16475_trigger_handler(int irq, void *p)  
> > > > > >         adis->spi->max_speed_hz =  
> > ADIS16475_BURST_MAX_SPEED;  
> > > > > >
> > > > > >         ret = spi_sync(adis->spi, &adis->msg);  
> > > > >
> > > > > Purely stylistic here.
> > > > > But, the restore from the cached variable could be done here in a
> > > > > single line.
> > > > > So. just moving [1] here.  
> > > >
> > > > You mean also doing it in the label? I thought about that and the
> > > > reason
> > > > why I didn't is that on a normal run, I want to reset the max freq as
> > > > soon
> > > > as possible so that if someone concurrently tries to read 'direct  
> > mode'  
> > > > attrs
> > > > gets the max freq. This was my reasoning but I admit that it's not  
> > that  
> > > > important so I will leave this to Jonathan's preference...
> > > >
> > > > Hmm now that I spoke about the concurrently access to IIO attr  
> > and  
> > > > being paranoid about
> > > > the compiler, I wonder if we should not use
> > > > WRITE_ONCE(adis->spi->max_speed_hz,
> > > > ADIS16475_BURST_MAX_SPEED)...  
> > >
> > > Hmmm, actually WRITE_ONCE would not be any help since the spi  
> > core  
> > > does not use READ_ONCE. So, if we are going to be paranoid about  
> > the  
> > > compiler and load/store tearing, I guess the only safe way here is to
> > > acquire the adis lock [btw, I'm a bit paranoid with this stuff :)]...
> > >
> > > Anyways, arguably the likelihood for this to happen is really, really  
> > small...
> > 
> > Really small, but needs fixing.  We shouldn't have a window in which
> > this  
> 
> Agreed!
> 
> > can happen.  So either we need to stop those attributes from reading
> > whilst
> > we are in buffered mode (via claim_direct_mode pattern) or we need
> > to put
> > a lock around this.  As an alternative, could we use the speed_hz field
> > in appropriate spi_transfer structures to tweak in this path without
> > affecting others?  That should make this concurrency problem an issue
> > for the spi core (which I'd assume handles this).  
> 
> Hmm, I like the 'speed_hz' approach as there's no reason to grab
> the lock because of a spi core tweak. As you said, with this, we push things
> to spi core. Going one step further, I think the most appropriate thing to do
> is actually come up with a new member in the 'adis_data' struct
> (like burst_max_speed_hz) and tweak the burst mode transfers accordingly in
> 'adis_update_scan_mode_burst()' (as there's no need to set this on every
> burst sample)...
> 
> If we are going the above path, what would be your preference? To add the
> patches to this series? Or to just fix this patch and [1] and push another series
> with the above changes? Hmm, since [1] would also depend on this, I guess the
> later approach would be better?
> 
> [1]: https://patchwork.kernel.org/project/linux-iio/patch/20210413092815.28626-1-nuno.sa@analog.com/

Make a new version of this series with the fix, then provide an update of [1]
that is probably going to be dependent on this series.

Given this is a fix, ideally we'll backport it which we don't need to do
for the new code introduced in [1].

Thanks,

Jonathan

> 
> - Nuno Sá
diff mbox series

Patch

diff --git a/drivers/iio/imu/adis16475.c b/drivers/iio/imu/adis16475.c
index 51b76444db0b..9dca7e506200 100644
--- a/drivers/iio/imu/adis16475.c
+++ b/drivers/iio/imu/adis16475.c
@@ -1067,8 +1067,10 @@  static irqreturn_t adis16475_trigger_handler(int irq, void *p)
 	adis->spi->max_speed_hz = ADIS16475_BURST_MAX_SPEED;
 
 	ret = spi_sync(adis->spi, &adis->msg);
-	if (ret)
+	if (ret) {
+		adis->spi->max_speed_hz = cached_spi_speed_hz;
 		goto check_burst32;
+	}
 
 	adis->spi->max_speed_hz = cached_spi_speed_hz;
 	buffer = adis->buffer;