From: Jonathan Cameron <jic23@kernel.org> To: Quentin Schulz <quentin.schulz@free-electrons.com>, jdelvare@suse.com, linux@roeck-us.net, knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net, maxime.ripard@free-electrons.com, wens@csie.org, lee.jones@linaro.org Cc: linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-iio@vger.kernel.org, linux-arm-kernel@lists.infradead.org, thomas.petazzoni@free-electrons.com, antoine.tenart@free-electrons.com Subject: Re: [PATCH v2 2/4] iio: adc: add support for Allwinner SoCs ADC Date: Wed, 20 Jul 2016 15:59:20 +0100 [thread overview] Message-ID: <583cc331-69f9-bea4-486b-323c10c65447@kernel.org> (raw) In-Reply-To: <f6e32bf0-f043-0d34-5190-18b89920bbfd@free-electrons.com> On 20/07/16 13:37, Quentin Schulz wrote: > On 18/07/2016 15:18, Jonathan Cameron wrote: > [...] >>> + >>> + if (!wait_for_completion_timeout(&info->completion, >>> + msecs_to_jiffies(100))) { >>> + ret = -ETIMEDOUT; >>> + goto out; >>> + } >>> + >>> + if (info->flags & SUNXI_GPADC_ARCH_SUN4I) >>> + *val = info->temp_data * 133 - 257000; >> Why report as processed? I'd just report them as raw with the scale >> and offset provided. It's not a big thing, but if we can leave it so >> that the conversion only occurs when desired, why not? >> >> For in kernel users, this all happen 'automagically' anyway ;) >> > > Mmmmh, in the code above we apply the scale on the raw value and then > the offset. While in iio_convert_raw_to_processed > (http://lxr.free-electrons.com/source/drivers/iio/inkern.c#L507), the > offset is applied before the scale. > > The way would be to factorize the computation by scale: > Now: *val = raw * scale + offset > Then: *val = (raw + offset/scale) * scale > > But the offset is an integer and offset/scale is therefore rounded. > Currently, we have the following values: > sun4i: -257000/133 = -1932.3308270676691 > sun5i: -144700/100 = -1447 > sun6i: -271000/167 = -1622.754491017964 > > Do we accept such rounding? Yes - how accurate do you think a temp sensor is - really not a problem. > > If not, we either stay with the processed value in read_raw or patch > inkern to add an offset to apply after having applied the scale to the > raw value (val2 from iio_channel_read is yet unused with > IIO_CHAN_INFO_OFFSET for example, we could use that to specify an > offset2 to apply after the switch(scale_type)-case). I don't really care that much if you just want to keep them as processed values. J > > [...] > Quentin >
WARNING: multiple messages have this Message-ID (diff)
From: jic23@kernel.org (Jonathan Cameron) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 2/4] iio: adc: add support for Allwinner SoCs ADC Date: Wed, 20 Jul 2016 15:59:20 +0100 [thread overview] Message-ID: <583cc331-69f9-bea4-486b-323c10c65447@kernel.org> (raw) In-Reply-To: <f6e32bf0-f043-0d34-5190-18b89920bbfd@free-electrons.com> On 20/07/16 13:37, Quentin Schulz wrote: > On 18/07/2016 15:18, Jonathan Cameron wrote: > [...] >>> + >>> + if (!wait_for_completion_timeout(&info->completion, >>> + msecs_to_jiffies(100))) { >>> + ret = -ETIMEDOUT; >>> + goto out; >>> + } >>> + >>> + if (info->flags & SUNXI_GPADC_ARCH_SUN4I) >>> + *val = info->temp_data * 133 - 257000; >> Why report as processed? I'd just report them as raw with the scale >> and offset provided. It's not a big thing, but if we can leave it so >> that the conversion only occurs when desired, why not? >> >> For in kernel users, this all happen 'automagically' anyway ;) >> > > Mmmmh, in the code above we apply the scale on the raw value and then > the offset. While in iio_convert_raw_to_processed > (http://lxr.free-electrons.com/source/drivers/iio/inkern.c#L507), the > offset is applied before the scale. > > The way would be to factorize the computation by scale: > Now: *val = raw * scale + offset > Then: *val = (raw + offset/scale) * scale > > But the offset is an integer and offset/scale is therefore rounded. > Currently, we have the following values: > sun4i: -257000/133 = -1932.3308270676691 > sun5i: -144700/100 = -1447 > sun6i: -271000/167 = -1622.754491017964 > > Do we accept such rounding? Yes - how accurate do you think a temp sensor is - really not a problem. > > If not, we either stay with the processed value in read_raw or patch > inkern to add an offset to apply after having applied the scale to the > raw value (val2 from iio_channel_read is yet unused with > IIO_CHAN_INFO_OFFSET for example, we could use that to specify an > offset2 to apply after the switch(scale_type)-case). I don't really care that much if you just want to keep them as processed values. J > > [...] > Quentin >
next prev parent reply other threads:[~2016-07-20 14:59 UTC|newest] Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-07-15 9:59 [PATCH v2 0/4] add support for Allwinner SoCs ADC Quentin Schulz 2016-07-15 9:59 ` Quentin Schulz 2016-07-15 9:59 ` [PATCH v2 1/4] hwmon: iio_hwmon: defer probe when no channel is found Quentin Schulz 2016-07-15 9:59 ` Quentin Schulz 2016-07-16 17:00 ` [v2,1/4] " Guenter Roeck 2016-07-16 17:00 ` Guenter Roeck 2016-07-18 10:02 ` Maxime Ripard 2016-07-18 10:02 ` Maxime Ripard 2016-07-18 13:29 ` Guenter Roeck 2016-07-18 13:29 ` Guenter Roeck 2016-07-15 9:59 ` [PATCH v2 2/4] iio: adc: add support for Allwinner SoCs ADC Quentin Schulz 2016-07-15 9:59 ` Quentin Schulz 2016-07-18 12:57 ` Maxime Ripard 2016-07-18 12:57 ` Maxime Ripard 2016-07-19 9:04 ` Quentin Schulz 2016-07-19 9:04 ` Quentin Schulz 2016-07-19 12:40 ` Maxime Ripard 2016-07-19 12:40 ` Maxime Ripard 2016-07-18 13:18 ` Jonathan Cameron 2016-07-18 13:18 ` Jonathan Cameron 2016-07-19 8:33 ` Quentin Schulz 2016-07-19 8:33 ` Quentin Schulz 2016-07-20 14:57 ` Jonathan Cameron 2016-07-20 14:57 ` Jonathan Cameron 2016-07-21 12:15 ` Quentin Schulz 2016-07-21 12:15 ` Quentin Schulz 2016-07-23 6:37 ` Jonathan Cameron 2016-07-23 6:37 ` Jonathan Cameron 2016-07-20 12:37 ` Quentin Schulz 2016-07-20 12:37 ` Quentin Schulz 2016-07-20 14:15 ` Crt Mori 2016-07-20 14:15 ` Crt Mori 2016-07-20 14:59 ` Jonathan Cameron [this message] 2016-07-20 14:59 ` Jonathan Cameron 2016-07-15 9:59 ` [PATCH v2 3/4] mfd: " Quentin Schulz 2016-07-15 9:59 ` Quentin Schulz 2016-07-18 13:02 ` Maxime Ripard 2016-07-18 13:02 ` Maxime Ripard 2016-07-19 12:04 ` Quentin Schulz 2016-07-19 12:04 ` Quentin Schulz 2016-07-18 13:25 ` Jonathan Cameron 2016-07-18 13:25 ` Jonathan Cameron 2016-07-19 7:31 ` Lee Jones 2016-07-19 7:31 ` Lee Jones 2016-07-20 15:01 ` Jonathan Cameron 2016-07-20 15:01 ` Jonathan Cameron 2016-07-21 12:12 ` Lee Jones 2016-07-21 12:12 ` Lee Jones 2016-07-21 20:08 ` Maxime Ripard 2016-07-21 20:08 ` Maxime Ripard 2016-07-22 13:55 ` Lee Jones 2016-07-22 13:55 ` Lee Jones 2016-07-23 6:42 ` Jonathan Cameron 2016-07-23 6:42 ` Jonathan Cameron 2016-07-25 9:55 ` Maxime Ripard 2016-07-25 9:55 ` Maxime Ripard 2016-07-19 8:35 ` Quentin Schulz 2016-07-19 8:35 ` Quentin Schulz 2016-07-15 9:59 ` [PATCH v2 4/4] hwmon: iio: add label for channels read by iio_hwmon Quentin Schulz 2016-07-15 9:59 ` Quentin Schulz 2016-07-15 14:03 ` Guenter Roeck 2016-07-15 14:03 ` Guenter Roeck 2016-07-15 14:36 ` Quentin Schulz 2016-07-15 14:36 ` Quentin Schulz 2016-07-16 2:53 ` Guenter Roeck 2016-07-16 2:53 ` Guenter Roeck 2016-07-18 12:24 ` Jonathan Cameron 2016-07-18 12:24 ` Jonathan Cameron 2016-07-19 6:55 ` Quentin Schulz 2016-07-19 6:55 ` Quentin Schulz 2016-07-20 14:49 ` Jonathan Cameron 2016-07-20 14:49 ` Jonathan Cameron
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=583cc331-69f9-bea4-486b-323c10c65447@kernel.org \ --to=jic23@kernel.org \ --cc=antoine.tenart@free-electrons.com \ --cc=jdelvare@suse.com \ --cc=knaack.h@gmx.de \ --cc=lars@metafoo.de \ --cc=lee.jones@linaro.org \ --cc=linux-arm-kernel@lists.infradead.org \ --cc=linux-hwmon@vger.kernel.org \ --cc=linux-iio@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux@roeck-us.net \ --cc=maxime.ripard@free-electrons.com \ --cc=pmeerw@pmeerw.net \ --cc=quentin.schulz@free-electrons.com \ --cc=thomas.petazzoni@free-electrons.com \ --cc=wens@csie.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.