On 01/16/2018 01:50 PM, Dan Carpenter wrote:
> On Tue, Jan 16, 2018 at 01:47:29PM +0100, Arnaud Pouliquen wrote:
>> Hello Dan
>>
>> On 01/16/2018 12:43 PM, Dan Carpenter wrote:
>>> Hello Arnaud Pouliquen,
>>>
>>> The patch eca949800d2d: "IIO: ADC: add stm32 DFSDM support for PDM
>>> microphone" from Jan 10, 2018, leads to the following static checker
>>> warning:
>>>
>>> drivers/iio/adc/stm32-dfsdm-adc.c:555 stm32_dfsdm_audio_dma_buffer_done()
>>> warn: potential shift truncation. '0xffffff00 (0,256-4294967040) << 8'
>>>
>>> drivers/iio/adc/stm32-dfsdm-adc.c
>>> 551 while (available >= indio_dev->scan_bytes) {
>>> 552 u32 *buffer = (u32 *)&adc->rx_buf[adc->bufi];
>>> 553
>>> 554 /* Mask 8 LSB that contains the channel ID */
>>> 555 *buffer = (*buffer & 0xFFFFFF00) << 8;
>>>
>>> Is this shift, correct? The comment just mentions that we're masking
>>> out the low bits.
>> Yes mask and shift are not correlated.
>> The Mask suppresses the 8 LSB that contain ID of the channel scanned
>> The shift is used for the 24 to 32 bits sample conversion.
>>
>
> If you wanted to silence the static checker warning you could change the
> mask to:
>
> *buffer = (*buffer & 0x00FFFF00) << 8;
Thanks for the proposal, fill free to send the patch, otherwise i will
add it in next patch series.
For my personal information which static checker warns on this line?
Regards
Arnaud
>
> regards,
> dan carpenter
>
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