From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= Subject: Re: [PATCH v4 00/15] acpi/pwm/i915: Convert pwm-crc and i915 driver's PWM code to use the atomic PWM API Date: Sat, 11 Jul 2020 08:19:01 +0200 Message-ID: <20200711061901.njwx3xofo4awcflg@pengutronix.de> References: <20200708211432.28612-1-hdegoede@redhat.com> <20200709141407.GA226971@ravnborg.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="nypanwwsq5jw6gz2" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-acpi-owner@vger.kernel.org To: Hans de Goede Cc: Sam Ravnborg , Thierry Reding , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Ville =?utf-8?B?U3lyasOkbMOk?= , "Rafael J . Wysocki" , Len Brown , linux-pwm@vger.kernel.org, linux-acpi@vger.kernel.org, intel-gfx , dri-devel@lists.freedesktop.org, Andy Shevchenko , Mika Westerberg List-Id: linux-pwm@vger.kernel.org --nypanwwsq5jw6gz2 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Hans, On Thu, Jul 09, 2020 at 04:40:56PM +0200, Hans de Goede wrote: > On 7/9/20 4:14 PM, Sam Ravnborg wrote: > > On Wed, Jul 08, 2020 at 11:14:16PM +0200, Hans de Goede wrote: > > > Here is v4 of my patch series converting the i915 driver's code for > > > controlling the panel's backlight with an external PWM controller to > > > use the atomic PWM API. See below for the changelog. > >=20 > > Why is it that i915 cannot use the pwm_bl driver for backlight? > > I have not studied the code - just wondering. >=20 > The intel_panel.c code deals with 7 different types of PWM controllers > which are built into the GPU + support for external PWM controllers > through the kernel's PWM subsystem. >=20 > pwm_bl will work for the external PWM controller case, but not for > the others. On top of that the intel_panel code integrates which > the video BIOS, getting things like frequency, minimum value > and if the range is inverted (0% duty =3D=3D backlight brightness max). > I'm not even sure if pwm_bl supports all of this, but even if it > does the intel_panel code handles this in a unified manner for > all supported PWM controllers, including the ones which are > an integral part of the GPU. pwm_bl handles inverted PWM just fine. I'm unsure what "integrates which the video BIOS" means, but I don't see how "handling 7 different types of PWM controllers explicitly and others using the PWM API" can be seen as "unified manner" compared to "provide a pwm driver for whatever might be in the GPU and then use generic code (PWM API, pwm_bl) to drive it". Maybe I'm not understanding some involved complexity here? Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig | Industrial Linux Solutions | https://www.pengutronix.de/ | --nypanwwsq5jw6gz2 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEfnIqFpAYrP8+dKQLwfwUeK3K7AkFAl8JWdEACgkQwfwUeK3K 7AnPNAf+MKmUG9Hx1mJmN2GjjMQrjge/K+GBb1l7uYqiy1ixtStSudPDHN1cqVfB /efzIuhjOG13a/TcwBf6FE+2IpqcJzB0fH5lRlki3jIk8LKEKYxd6yESQkdAmf6Q b3wBrveA8ogMLODq3SG/JWpONSMAZ0Dimi0bJgYIMTi5j5M4k5rloIAi+VbuKf8O gDxDo2yMtEF3mVyFoClxJ0GYCqShchZLRa7oalK/yD+uJNcAebZN+BWuhwXFpSQM JG9F4kI7SJvjJzZjwQlWr8RMh4LTdfHB2LlA6i4mEUAgvrB1Rg68sSDV4ZLXCpD4 LRN1sSRmYdYmK2gvSwJ7xIOQYTx+Tg== =UoeA -----END PGP SIGNATURE----- --nypanwwsq5jw6gz2--