From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <1501605706.29303.339.camel@linux.intel.com> Subject: Re: [PATCH v2 1/2] iio: adc: ti-ads7950: Allow to use on ACPI platforms From: Andy Shevchenko To: David Lechner , Jonathan Cameron Cc: Hartmut Knaack , Lars-Peter Clausen , linux-iio@vger.kernel.org Date: Tue, 01 Aug 2017 19:41:46 +0300 In-Reply-To: <51d5783f-4a7d-b51e-fd45-e4d84576f1c3@lechnology.com> References: <20170728222015.43574-1-andriy.shevchenko@linux.intel.com> <20170728222015.43574-2-andriy.shevchenko@linux.intel.com> <9d74cad7-be8e-9893-58bd-9fdd50298723@lechnology.com> <20170730143158.3b907e8f@kernel.org> <1501602326.29303.332.camel@linux.intel.com> <51d5783f-4a7d-b51e-fd45-e4d84576f1c3@lechnology.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 List-ID: On Tue, 2017-08-01 at 11:21 -0500, David Lechner wrote: > On 08/01/2017 10:45 AM, Andy Shevchenko wrote: > >     > > > > > + /* Use hard coded value for reference voltage in ACPI > > > > > case */ > > > > > + if (ACPI_COMPANION(&spi->dev)) > > > > > + st->vref_mv = TI_ADS7950_VA_MV_ACPI_DEFAULT; > > > > > > > > Instead of checking or ACPI, you could just say "if we have a > > > > dummy > > > > regulator, then use the default value". > > > > > > > Agreed. Sounds sensible to me.  Hopefully in DT people will > > > provide the right regulator, but chances are this won't > > > always happen. > > > > There is no call like > > regulator_is_dummy() > > (and, looking into the code of regulator framework, can't be) > > > > Can you elaborate a bit, maybe I'm missing something obvious? > > > > I haven't tested this, but shouldn't regulator_get_voltage() return > an  > error for a dummy regulator? You could use this as your test. While it would work it's very fragile. _regulator_get_voltage() will return error code even for normal regulators if something happened there. And user gets an impression that everything is okay while it's not. So, I wouldn't go this way. > > static int ti_ads7950_get_range(struct ti_ads7950_state *st) > { > int vref; > > vref = regulator_get_voltage(st->reg); > if (vref < 0) > - return vref; > + vref = 2500000; > > vref /= 1000; > > if (st->settings & TI_ADS7950_CR_RANGE_5V) > vref *= 2; > > return vref; > } > -- Andy Shevchenko Intel Finland Oy