Messages in this thread | | | From | Andy Shevchenko <> | Date | Mon, 22 May 2023 13:15:03 +0300 | Subject | Re: [PATCH v2 1/2] iio/adc: ingenic: Fix channel offsets in buffer |
| |
On Mon, May 22, 2023 at 1:59 AM Artur Rojek <contact@artur-rojek.eu> wrote: > > Consumers expect the buffer to only contain enabled channels. While > preparing the buffer, the driver makes two mistakes: > 1) It inserts empty data for disabled channels. > 2) Each ADC readout contains samples for two 16-bit channels. If either > of them is active, the whole 32-bit sample is pushed into the buffer > as-is. > > Both of those issues cause the active channels to appear at the wrong > offsets in the buffer. Fix the above by demuxing samples for active > channels only. > > This has remained unnoticed, as all the consumers so far were only using > channels 0 and 1, leaving them unaffected by changes introduced in this > commit.
...
> + u16 tdat[6]; > + u32 val; > + > + memset(tdat, 0, ARRAY_SIZE(tdat));
Yeah, as LKP tells us this should be sizeof() instead of ARRAY_SIZE().
> + for (i = 0; mask && i < ARRAY_SIZE(tdat); mask >>= 2) { > + if (mask & 0x3) {
(for the consistency it has to be GENMASK(), but see below)
First of all, strictly speaking we should use the full mask without limiting it to the 0 element in the array (I'm talking about active_scan_mask).
That said, we may actually use bit operations here in a better way, i.e.
unsigned long mask = active_scan_mask[0] & (active_scan_mask[0] - 1);
j = 0; for_each_set_bit(i, active_scan_mask, ...) { val = readl(...); /* Two channels per sample. Demux active. */ tdat[j++] = val >> (16 * (i % 2)); }
> + val = readl(adc->base + JZ_ADC_REG_ADTCH); > + /* Two channels per sample. Demux active. */ > + if (mask & BIT(0)) > + tdat[i++] = val & 0xffff; > + if (mask & BIT(1)) > + tdat[i++] = val >> 16; > + } > }
-- With Best Regards, Andy Shevchenko
| |