Use spi_is_bpw_supported() instead of directly accessing spi->controller
->bits_per_word_mask. bits_per_word_mask may be 0, which implies that
8-bits-per-word is supported. spi_is_bpw_supported() takes this into
account while spi_ctrl_mask == SPI_BPW_MASK(8) does not.

Closes: https://lore.kernel.org/linux-spi/c8b8a963-6cef-4c9b-bfef-dab2b7bd0b0f@sirena.org.uk/
Signed-off-by: David Lechner <dlechner@baylibre.com>
---
 drivers/iio/adc/ad7949.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c
index edd0c3a35ab73cca5ff87632e4d588eb5d712b47..202561cad4012b67e23ad6d3623c913cfef35e68 100644
--- a/drivers/iio/adc/ad7949.c
+++ b/drivers/iio/adc/ad7949.c
@@ -308,7 +308,6 @@ static void ad7949_disable_reg(void *reg)
 
 static int ad7949_spi_probe(struct spi_device *spi)
 {
-	u32 spi_ctrl_mask = spi->controller->bits_per_word_mask;
 	struct device *dev = &spi->dev;
 	const struct ad7949_adc_spec *spec;
 	struct ad7949_adc_chip *ad7949_adc;
@@ -337,11 +336,11 @@ static int ad7949_spi_probe(struct spi_device *spi)
 	ad7949_adc->resolution = spec->resolution;
 
 	/* Set SPI bits per word */
-	if (spi_ctrl_mask & SPI_BPW_MASK(ad7949_adc->resolution)) {
+	if (spi_is_bpw_supported(spi, ad7949_adc->resolution)) {
 		spi->bits_per_word = ad7949_adc->resolution;
-	} else if (spi_ctrl_mask == SPI_BPW_MASK(16)) {
+	} else if (spi_is_bpw_supported(spi, 16)) {
 		spi->bits_per_word = 16;
-	} else if (spi_ctrl_mask == SPI_BPW_MASK(8)) {
+	} else if (spi_is_bpw_supported(spi, 8)) {
 		spi->bits_per_word = 8;
 	} else {
 		dev_err(dev, "unable to find common BPW with spi controller\n");

---
base-commit: 4c6073fec2fee4827fa0dd8a4ab4e6f7bbc05ee6
change-id: 20250611-iio-adc-ad7949-use-spi_is_bpw_supported-17f1293abf88

Best regards,
-- 
David Lechner <dlechner@baylibre.com>

On Wed, Jun 11, 2025 at 10:04:58AM -0500, David Lechner wrote:
> Use spi_is_bpw_supported() instead of directly accessing spi->controller
> ->bits_per_word_mask. bits_per_word_mask may be 0, which implies that
> 8-bits-per-word is supported. spi_is_bpw_supported() takes this into
> account while spi_ctrl_mask == SPI_BPW_MASK(8) does not.

> Closes: https://lore.kernel.org/linux-spi/c8b8a963-6cef-4c9b-bfef-dab2b7bd0b0f@sirena.org.uk/

Reported-by yourself. I'm wondering if the Closes adds a value in this case.
Otherwise I can do the same to maybe 10% of my patches, for instance. But
I don't think I put Closes tag on whatever improvement potential bug fix
I do report (read: notice) myself.

> Signed-off-by: David Lechner <dlechner@baylibre.com>

Code wise LGTM,
Reviewed-by: Andy Shevchenko <andy@kernel.org>

-- 
With Best Regards,
Andy Shevchenko

On 6/11/25 10:15 AM, Andy Shevchenko wrote:
> On Wed, Jun 11, 2025 at 10:04:58AM -0500, David Lechner wrote:
>> Use spi_is_bpw_supported() instead of directly accessing spi->controller
>> ->bits_per_word_mask. bits_per_word_mask may be 0, which implies that
>> 8-bits-per-word is supported. spi_is_bpw_supported() takes this into
>> account while spi_ctrl_mask == SPI_BPW_MASK(8) does not.
> 
>> Closes: https://lore.kernel.org/linux-spi/c8b8a963-6cef-4c9b-bfef-dab2b7bd0b0f@sirena.org.uk/
> 
> Reported-by yourself. I'm wondering if the Closes adds a value in this case.
> Otherwise I can do the same to maybe 10% of my patches, for instance. But
> I don't think I put Closes tag on whatever improvement potential bug fix
> I do report (read: notice) myself.

I included it so that Da Xue will know that this has been resolved and
doesn't need to do anything more. Normally I would have not included
it though.

> 
>> Signed-off-by: David Lechner <dlechner@baylibre.com>
> 
> Code wise LGTM,
> Reviewed-by: Andy Shevchenko <andy@kernel.org>
>

On Wed, 11 Jun 2025 10:21:56 -0500
David Lechner <dlechner@baylibre.com> wrote:

> On 6/11/25 10:15 AM, Andy Shevchenko wrote:
> > On Wed, Jun 11, 2025 at 10:04:58AM -0500, David Lechner wrote:  
> >> Use spi_is_bpw_supported() instead of directly accessing spi->controller  
> >> ->bits_per_word_mask. bits_per_word_mask may be 0, which implies that  
> >> 8-bits-per-word is supported. spi_is_bpw_supported() takes this into
> >> account while spi_ctrl_mask == SPI_BPW_MASK(8) does not.  
> >   
> >> Closes: https://lore.kernel.org/linux-spi/c8b8a963-6cef-4c9b-bfef-dab2b7bd0b0f@sirena.org.uk/  
> > 
> > Reported-by yourself. I'm wondering if the Closes adds a value in this case.
> > Otherwise I can do the same to maybe 10% of my patches, for instance. But
> > I don't think I put Closes tag on whatever improvement potential bug fix
> > I do report (read: notice) myself.  
> 
> I included it so that Da Xue will know that this has been resolved and
> doesn't need to do anything more. Normally I would have not included
> it though.

If I followed the discussion correctly does this need a fixes tag?

> 
> >   
> >> Signed-off-by: David Lechner <dlechner@baylibre.com>  
> > 
> > Code wise LGTM,
> > Reviewed-by: Andy Shevchenko <andy@kernel.org>
> >   
>

On 6/11/25 11:55 AM, Jonathan Cameron wrote:
> On Wed, 11 Jun 2025 10:21:56 -0500
> David Lechner <dlechner@baylibre.com> wrote:
> 
>> On 6/11/25 10:15 AM, Andy Shevchenko wrote:
>>> On Wed, Jun 11, 2025 at 10:04:58AM -0500, David Lechner wrote:  
>>>> Use spi_is_bpw_supported() instead of directly accessing spi->controller  
>>>> ->bits_per_word_mask. bits_per_word_mask may be 0, which implies that  
>>>> 8-bits-per-word is supported. spi_is_bpw_supported() takes this into
>>>> account while spi_ctrl_mask == SPI_BPW_MASK(8) does not.  
>>>   
>>>> Closes: https://lore.kernel.org/linux-spi/c8b8a963-6cef-4c9b-bfef-dab2b7bd0b0f@sirena.org.uk/  
>>>
>>> Reported-by yourself. I'm wondering if the Closes adds a value in this case.
>>> Otherwise I can do the same to maybe 10% of my patches, for instance. But
>>> I don't think I put Closes tag on whatever improvement potential bug fix
>>> I do report (read: notice) myself.  
>>
>> I included it so that Da Xue will know that this has been resolved and
>> doesn't need to do anything more. Normally I would have not included
>> it though.
> 
> If I followed the discussion correctly does this need a fixes tag?

I supposed it doesn't hurt. It could be possible that someone tries to
use an older stable kernel with a SPI controller that didn't set the
flags, in which case there could be a problem.

Fixes: 0b2a740b424e ("iio: adc: ad7949: enable use with non 14/16-bit controllers")

> 
>>
>>>   
>>>> Signed-off-by: David Lechner <dlechner@baylibre.com>  
>>>
>>> Code wise LGTM,
>>> Reviewed-by: Andy Shevchenko <andy@kernel.org>
>>>   
>>
>

On Wed, 11 Jun 2025 12:00:27 -0500
David Lechner <dlechner@baylibre.com> wrote:

> On 6/11/25 11:55 AM, Jonathan Cameron wrote:
> > On Wed, 11 Jun 2025 10:21:56 -0500
> > David Lechner <dlechner@baylibre.com> wrote:
> >   
> >> On 6/11/25 10:15 AM, Andy Shevchenko wrote:  
> >>> On Wed, Jun 11, 2025 at 10:04:58AM -0500, David Lechner wrote:    
> >>>> Use spi_is_bpw_supported() instead of directly accessing spi->controller    
> >>>> ->bits_per_word_mask. bits_per_word_mask may be 0, which implies that    
> >>>> 8-bits-per-word is supported. spi_is_bpw_supported() takes this into
> >>>> account while spi_ctrl_mask == SPI_BPW_MASK(8) does not.    
> >>>     
> >>>> Closes: https://lore.kernel.org/linux-spi/c8b8a963-6cef-4c9b-bfef-dab2b7bd0b0f@sirena.org.uk/    
> >>>
> >>> Reported-by yourself. I'm wondering if the Closes adds a value in this case.
> >>> Otherwise I can do the same to maybe 10% of my patches, for instance. But
> >>> I don't think I put Closes tag on whatever improvement potential bug fix
> >>> I do report (read: notice) myself.    
> >>
> >> I included it so that Da Xue will know that this has been resolved and
> >> doesn't need to do anything more. Normally I would have not included
> >> it though.  
> > 
> > If I followed the discussion correctly does this need a fixes tag?  
> 
> I supposed it doesn't hurt. It could be possible that someone tries to
> use an older stable kernel with a SPI controller that didn't set the
> flags, in which case there could be a problem.
> 
> Fixes: 0b2a740b424e ("iio: adc: ad7949: enable use with non 14/16-bit controllers")
Applied to the fixes-togreg branch of iio.git.

I didn't mark it for stable purely because it would have been obvious
I think if anyone actually hit this.

Jonathan

> 
> >   
> >>  
> >>>     
> >>>> Signed-off-by: David Lechner <dlechner@baylibre.com>    
> >>>
> >>> Code wise LGTM,
> >>> Reviewed-by: Andy Shevchenko <andy@kernel.org>
> >>>     
> >>  
> >   
>