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.
Regards,
Arnaud
>
> 556 available -= indio_dev->scan_bytes;
> 557 adc->bufi += indio_dev->scan_bytes;
> 558 if (adc->bufi >= adc->buf_sz) {
> 559 if (adc->cb)
> 560 adc->cb(&adc->rx_buf[old_pos],
> 561 adc->buf_sz - old_pos, adc->cb_priv);
> 562 adc->bufi = 0;
> 563 old_pos = 0;
> 564 }
> 565 }
> 566 if (adc->cb)
> 567 adc->cb(&adc->rx_buf[old_pos], adc->bufi - old_pos,
> 568 adc->cb_priv);
> 569 }
>
> regards,
> dan carpenter
>
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