Re: [PATCH v5 00/16] acpi/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: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: linux-pwm@vger.kernel.org,
	intel-gfx <intel-gfx@lists.freedesktop.org>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	linux-acpi@vger.kernel.org,
	"Thierry Reding" <thierry.reding@gmail.com>,
	dri-devel@lists.freedesktop.org,
	"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Mika Westerberg" <mika.westerberg@linux.intel.com>,
	"Len Brown" <lenb@kernel.org>
Subject: Re: [PATCH v5 00/16] acpi/pwm/i915: Convert pwm-crc and i915 driver's PWM code to use the atomic PWM API
Date: Sat, 1 Aug 2020 16:38:16 +0200	[thread overview]
Message-ID: <e8f93474-1775-b20c-f9f2-e33592a02028@redhat.com> (raw)
In-Reply-To: <20200729105436.GT3703480@smile.fi.intel.com>

Hi,

On 7/29/20 12:54 PM, Andy Shevchenko wrote:
> On Fri, Jul 17, 2020 at 03:37:37PM +0200, Hans de Goede wrote:
>> Hi All,
>>
>> Here is v5 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.
>>
>> This series 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
>>
>> The involved acpi_lpss and pwm drivers do not see a whole lot of churn,
>> so the plan is to merge this all through drm-intel-next-queued (dinq)
>> once all the patches are reviewed / have acks.
>>
>> Specifically patches 5-9, 11 still need an Acked- / Reviewed-by
>>
>> Andy, can you please take a look at the unreviewed patches? Specifically
>> patches 5-6 should address your review remarks from v4 of this set
>> and I've addressed your review remarks on patches 7-9 in v3 already.
>> A review of patch 11 would also be welcome
> 
> Done. Sorry for a delay.
> 
> One comment to consider, though. There are three channels in that PWM AFAIU.
> One of them is backlight control, another one can be attached to haptics. The
> concern is how this series may (or may not?) affect haptics behaviour.

When you say "in that PWM" do you mean the LPSS one or the CRC one ?

The LPSS patches are all fixes, they don't change behavior, so those
should be fine for the haptics.

The CRC PWM driver patches do make it honor the requested output frequency,
where before, because of a bug, it would stick with the out frequency
setup by the firmware (or the power-on-reset value if no value is set
by the firmware). This fix causing this is very clearly correct, but
it could have unexpected side-effects.

However I guess that you are talking about the LPSS PWM controllers
and there I expect no impact on haptic or other non backlight users
from these changes.

Regards,

Hans

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