On Thu, 13 Aug 2020 at 21:41, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote: > > On Thu, Aug 13, 2020 at 4:04 PM Crt Mori <cmo@xxxxxxxxxxx> wrote: > > On Thu, 13 Aug 2020 at 13:24, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote: > > > On Thu, Aug 13, 2020 at 2:14 PM Crt Mori <cmo@xxxxxxxxxxx> wrote: > > > > On Thu, 13 Aug 2020 at 13:03, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote: > > > > > On Thu, Aug 13, 2020 at 10:53 AM Crt Mori <cmo@xxxxxxxxxxx> wrote: > > ... > > > > > > I don't see how it prevents using iopoll.h. It uses usleep_range() > > > > > under the hood in the same way you did here, but open coded. > > > > > > > > > > > > > One loop is indeed 10ms and that is not the problem, the problem is > > > > that timeout is at least 3 calls of this data ready (3 channels), so > > > > that is at minimum 30ms of timeout, or it could even be 4 in worse > > > > case scenario and that is outside of the range for usleep to measure. > > > > So in case of the other loop, where we wait 200ms for channel refresh > > > > it is also out of scope. Timeout should be in number of tries or in > > > > msleep range if you ask me. > > > > > > I still didn't buy it. You have in both cases usleep_range(). Why in > > > your case it's okay and in regmap_read_poll_timeout() is not? > > > > > > > I tried and it did not work, so then I read the manual. Looking into > > > > * regmap_read_poll_timeout_atomic - Poll until a condition is met or a > > timeout occurs > > Why _atomic?! I just pasted something, it is the same as for non _atomic > > > ... > > * @delay_us: Time to udelay between reads in us (0 tight-loops). > > * Should be less than ~10us since udelay is used > > * (see Documentation/timers/timers-howto.rst). > > * @timeout_us: Timeout in us, 0 means never timeout > > > > > > So I went to read Documentation/timers/timers-howto.rst > > > > SLEEPING FOR ~USECS OR SMALL MSECS ( 10us - 20ms): > > * Use usleep_range > > > > - Why not msleep for (1ms - 20ms)? > > Explained originally here: > > http://lkml.org/lkml/2007/8/3/250 > > > > msleep(1~20) may not do what the caller intends, and > > will often sleep longer (~20 ms actual sleep for any > > value given in the 1~20ms range). In many cases this > > is not the desired behavior. > > > > Since I am above the 20ms range, it is too much for usleep_range and > > that proved to be a case as I got -ETIMEOUT and the desired channels > > were not read. > > > > > ... > > > > > > > > > > > - while (tries-- > 0) { > > > > > > + do { > > > > > > ret = regmap_read(data->regmap, MLX90632_REG_STATUS, > > > > > > ®_status); > > > > > > if (ret < 0) > > > > > > return ret; > > > > > > - if (reg_status & MLX90632_STAT_DATA_RDY) > > > > > > - break; > > > > > > usleep_range(10000, 11000); > > You use here usleep_range(). The same is used for > regmap_read_poll_timeout(). What's the difference? > > Since it uses 1/4 of the range you probably need to update tries and > timeout_us to make it work. > Timeout_us here needs to be in one case 100 * 10ms (maybe not realistic as we could live with number of around 40 * 10ms), but this is a lot more than proposed range of usleep which Is up to 20ms. Even in best case this timeout should be 40 ms to give enough time to measure 2 channels for sure. So with the current timeout_us requirement we are outside of the range of the udelay timer and that is why I would need a macro with number of tries, not with the timeout value (or timeout value of ms). > > > > > > - } > > > > > > + } while (!(reg_status & MLX90632_STAT_DATA_RDY) && tries--); > > > > > > > > > > > > if (tries < 0) { > > > > > > dev_err(&data->client->dev, "data not ready"); > > -- > With Best Regards, > Andy Shevchenko
