linux-kernel - [PATCH 0/3] pwm-backlight: add subdrivers & Tegra support

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Message-Id: <1358591420-7790-1-git-send-email-acourbot@nvidia.com>
Date:	Sat, 19 Jan 2013 19:30:17 +0900
From:	Alexandre Courbot <acourbot@...dia.com>
To:	Thierry Reding <thierry.reding@...onic-design.de>,
	Stephen Warren <swarren@...dotorg.org>
Cc:	linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-tegra@...r.kernel.org, Mark Zhang <markz@...dia.com>,
	gnurou@...il.com, Alexandre Courbot <acourbot@...dia.com>
Subject: [PATCH 0/3] pwm-backlight: add subdrivers & Tegra support

This series introduces a way to use pwm-backlight hooks with platforms
that use the device tree through a subdriver system. It also adds support
for the Tegra-based Ventana board, adding the last missing block to enable
its panel. Support for other Tegra board can thus be easily added.

I have something else in mind to properly support this (power
sequences), but this work relies on the GPIO subsystem redesign which will
take some time. The pwm-backlight subdrivers can do the job by the meantime.

There are a few design points that might need to be discussed:
1) Link order is important: subdrivers register themselves in their
module_init function, which must be called before pwm-backlight's probe.
This forbids linking subdrivers as separate modules from pwm-backlight.
2) The subdriver's data is temporarily passed through the backlight
device's driver data. This should not hurt, but maybe there is a better way
to do this.
3) Subdrivers must add themselves into pwm-backlight's own of_device_id
table. It would be cleaner to not have to list subdrivers into
pwm-backlight's main file, but I cannot think of a way to do otherwise.

Suggestions for the 3 points listed above are very welcome - in any case,
I hope to make this converge into something mergeable quickly.

Note that these patches are the last missing block to get a functional
panel on Tegra boards. Using 3.8rc4 and these patches, the internal panel
on Ventana is usable out-of-the-box. Yay.

Alexandre Courbot (3):
  pwm-backlight: add subdriver mechanism
  tegra: pwm-backlight: add tegra pwm-bl driver
  tegra: ventana: of: add host1x device to DT

 arch/arm/boot/dts/tegra20-ventana.dts  |  29 +++++-
 arch/arm/configs/tegra_defconfig       |   1 +
 drivers/video/backlight/Kconfig        |   7 ++
 drivers/video/backlight/Makefile       |   4 +
 drivers/video/backlight/pwm_bl.c       |  70 ++++++++++++++-
 drivers/video/backlight/pwm_bl_tegra.c | 159 +++++++++++++++++++++++++++++++++
 include/linux/pwm_backlight.h          |  15 ++++
 7 files changed, 281 insertions(+), 4 deletions(-)
 create mode 100644 drivers/video/backlight/pwm_bl_tegra.c

-- 
1.8.1.1

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