Re: pwm/i915: Convert pwm-crc and i915 driver's PWM code to use the atomic PWM API

From: Hans de Goede <hdegoede@redhat.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Daniel Vetter" <daniel@ffwll.ch>
Cc: "Thierry Reding" <thierry.reding@gmail.com>,
	"Jani Nikula" <jani.nikula@linux.intel.com>,
	"Joonas Lahtinen" <joonas.lahtinen@linux.intel.com>,
	"Ville Syrjälä" <ville.syrjala@linux.intel.com>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	"Len Brown" <lenb@kernel.org>,
	linux-pwm@vger.kernel.org, linux-acpi@vger.kernel.org,
	intel-gfx <intel-gfx@lists.freedesktop.org>,
	dri-devel@lists.freedesktop.org,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"Mika Westerberg" <mika.westerberg@linux.intel.com>
Subject: Re: pwm/i915: Convert pwm-crc and i915 driver's PWM code to use the atomic PWM API
Date: Fri, 12 Jun 2020 19:04:51 +0200	[thread overview]
Message-ID: <58972efb-003d-ca87-0637-ece4c93aeeb5@redhat.com> (raw)
In-Reply-To: <20200611212144.i7ma7kriznidds4r@taurus.defre.kleine-koenig.org>

Hi,

On 6/11/20 11:21 PM, Uwe Kleine-König wrote:
> Hello,
> 
> On Mon, Jun 08, 2020 at 04:35:00PM +0200, Daniel Vetter wrote:
>> On Sat, Jun 06, 2020 at 10:25:45PM +0200, Hans de Goede wrote:
>>> Hi All,
>>>
>>> This patch series converts the i915 driver's cpde for controlling the
>>> panel's backlight with an external PWM controller to use the atomic PWM API.
>>>
>>> Initially the plan was for this series to consist of 2 parts:
>>> 1. convert the pwm-crc driver to support the atomic PWM API and
>>> 2. convert the i915 driver's PWM code to use the atomic PWM API.
>>>
>>> But during testing I've found a number of bugs in the pwm-lpss and I
>>> found that the acpi_lpss code needs some special handling because of
>>> some ugliness found in most Cherry Trail DSDTs.
>>>
>>> So now this series has grown somewhat large and consists of 4 parts:
>>>
>>> 1. acpi_lpss fixes workarounds for Cherry Trail DSTD nastiness
>>> 2. various fixes to the pwm-lpss driver
>>> 3. convert the pwm-crc driver to support the atomic PWM API and
>>> 4. convert the i915 driver's PWM code to use the atomic PWM API
>>>
>>> So we need to discuss how to merge this (once it passes review).
>>> Although the inter-dependencies are only runtime I still think we should
>>> make sure that 1-3 are in the drm-intel-next-queued (dinq) tree before
>>> merging the i915 changes. Both to make sure that the intel-gfx CI system
>>> does not become unhappy and for bisecting reasons.
>>
>> Simplest is if acpi acks the acpi patches for merging through
>> drm-intel.git. Second simplest is topic branch (drm-intel maintainers can
>> do that) with the entire pile, which then acpi and drm-intel can both pull
>> in.
>>
>> Up to the two maintainer teams to figure this one out.
> 
> I'm unclear about the dependencies

There is a runtime dependency of the i915 changes on the PWM changes
and since the intel-gfx folks use a lot of CI, we this need to get the
PWM changes into the drm-intel tree before the i915 changes can land.

> , but the changes to drivers/pwm need
> an ack (or processing) by the PWM team.

Of course, I asked for an Acked-by from the PWM team
(once this passes review) for merging this through
the drm-intel tree, as the i915 driver is the main
(only AFAIK) consumer of the PWMs controlled by these
2 drivers.  Daniel <snip>-ed that bit when he replied.

Regards,

Hans