From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH v4 06/16] pwm: lpss: Correct get_state result for base_unit == 0 Date: Thu, 9 Jul 2020 17:50:13 +0300 Message-ID: <20200709145013.GA3703480@smile.fi.intel.com> References: <20200708211432.28612-1-hdegoede@redhat.com> <20200708211432.28612-7-hdegoede@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20200708211432.28612-7-hdegoede@redhat.com> Sender: linux-acpi-owner@vger.kernel.org To: Hans de Goede Cc: Thierry Reding , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Ville =?iso-8859-1?Q?Syrj=E4l=E4?= , "Rafael J . Wysocki" , Len Brown , linux-pwm@vger.kernel.org, intel-gfx , dri-devel@lists.freedesktop.org, Mika Westerberg , linux-acpi@vger.kernel.org List-Id: linux-pwm@vger.kernel.org On Wed, Jul 08, 2020 at 11:14:22PM +0200, Hans de Goede wrote: > The datasheet specifies that programming the base_unit part of the > ctrl register to 0 results in a contineous low signal. > > Adjust the get_state method to reflect this by setting pwm_state.period > to 1 and duty_cycle to 0. ... > + if (freq == 0) { > + /* In this case the PWM outputs a continous low signal */ > + state->period = 1; I guess this should be something like half of the range (so base unit calc will give 128). Because with period = 1 (too small) it will give too small base unit (if apply) and as a result we get high frequency pulses. > + state->duty_cycle = 0; > + } else { > state->period = NSEC_PER_SEC / (unsigned long)freq; > + on_time_div *= state->period; > + do_div(on_time_div, 255); > + state->duty_cycle = on_time_div; > + } -- With Best Regards, Andy Shevchenko