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* [PATCH v3 0/3] phy: Add exynos-simple-phy driver
@ 2014-05-14 19:17 Rahul Sharma
  2014-05-14 19:17 ` [PATCH v3 1/3] " Rahul Sharma
                   ` (2 more replies)
  0 siblings, 3 replies; 24+ messages in thread
From: Rahul Sharma @ 2014-05-14 19:17 UTC (permalink / raw)
  To: linux-kernel, linux-samsung-soc, dri-devel
  Cc: a.hajda, t.stanislaws, devicetree, kgene.kim, kishon,
	kyungmin.park, robh+dt, grant.likely, sylvester.nawrocki, joshi,
	Rahul Sharma

From: Rahul Sharma <Rahul.Sharma@samsung.com>

Hi All,

This series has been originally proposed by Tomasz Stanislawski. With
his permission, I have addressed the following review comments in V3.

Changelog:
v3:
	* Implement lazy-init of PHYs.
	* Use MACROs instead of numbers to represent phys.
	* Use regmap interface to access PMU registers.

It is based on "Next" branch in Kishon Vijay Abraham's tree at
https://git.kernel.org/cgit/linux/kernel/git/kishon/linux-phy.git/

/* Original Message from Tomasz Stanislawski <t.stanislaws@samsung.com> */

The Samsung SoCs from Exynos family are enhanced with a bunch of devices that
provide functionality of a physical layer for interfaces like USB, HDMI, SATA,
etc. They are controlled by a simple interface, often a single bit that enables
and/or resets the physical layer.

An IP driver should to control such a controller in an abstract manner.
Therefore, such 'enablers' were implemented as clocks in older versions of
Linux kernel.  With the dawn of PHY subsystems, PHYs become a natural way of
exporting the 'enabler' functionality to drivers.  However, there is an
unexpected consequence. Some of those 1-bit PHYs were implemented as separate
drivers.  This means that one has to create a struct device, struct phy, its
phy provider and 100-150 lines of driver code to basically set one bit.

The DP phy driver is a good example:
https://lkml.org/lkml/2013/7/18/53

And simple-phy RFC (shares only driver code but not other resources):
https://lkml.org/lkml/2013/10/21/313

To avoid waste of resources I propose to create all such 1-bit phys from Exynos
SoC using a single device, driver and phy provider.

This patchset contains a proposed solution.

All comment are welcome.

Hopefully in future the functionality introduced by this patch may be merged
into a larger Power Management Unit (PMU) gluer driver.  On Samsusng SoC , the
PMU part contains a number of register barely linked to power management (like
clock gating, clock dividers, CPU resetting, etc.).  It may be tempting to
create a hybrid driver that export clocks/phys/etc that are controlled by PMU
unit.

Alternative solutions might be:
* exporting a regmap to the IP driver and allow the driver to control the PHY layer
  like in the patch:
  http://thread.gmane.org/gmane.linux.kernel.samsung-soc/28617/focus=28648

* create a dedicated power domain for hdmiphy

Regards,
Tomasz Stanislawski

v2:
	* rename to exynos-simple-phy
	* fix usage of devm_ioremap()
	* add documentation for DT bindings
	* add patches to client drivers

v1: initial version

Tomasz Stanislawski (3):
  phy: Add exynos-simple-phy driver
  drm: exynos: hdmi: use hdmiphy as PHY
  s5p-tv: hdmi: use hdmiphy as PHY

 .../devicetree/bindings/phy/samsung-phy.txt        |   56 ++++++
 drivers/gpu/drm/exynos/exynos_hdmi.c               |   11 +-
 drivers/media/platform/s5p-tv/hdmi_drv.c           |   11 +-
 drivers/phy/Kconfig                                |    5 +
 drivers/phy/Makefile                               |    1 +
 drivers/phy/exynos-simple-phy.c                    |  189 ++++++++++++++++++++
 include/dt-bindings/phy/exynos-simple-phy.h        |   27 +++
 7 files changed, 290 insertions(+), 10 deletions(-)
 create mode 100644 drivers/phy/exynos-simple-phy.c
 create mode 100644 include/dt-bindings/phy/exynos-simple-phy.h

-- 
1.7.9.5


^ permalink raw reply	[flat|nested] 24+ messages in thread

end of thread, other threads:[~2014-05-20  5:12 UTC | newest]

Thread overview: 24+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-05-14 19:17 [PATCH v3 0/3] phy: Add exynos-simple-phy driver Rahul Sharma
2014-05-14 19:17 ` [PATCH v3 1/3] " Rahul Sharma
2014-05-14 20:01   ` Tomasz Figa
2014-05-15  4:01     ` Rahul Sharma
2014-05-15 21:44       ` Tomasz Figa
2014-05-16  9:42         ` Rahul Sharma
2014-05-16 10:35           ` Rahul Sharma
2014-05-16 10:50             ` Tomasz Figa
2014-05-16 14:30               ` Rahul Sharma
2014-05-16 14:49                 ` Tomasz Figa
2014-05-19  7:10                   ` Rahul Sharma
2014-05-19 10:54                     ` Tomasz Figa
2014-05-20  5:12                       ` Rahul Sharma
2014-05-14 22:14   ` Thierry Reding
2014-05-15  5:19     ` Rahul Sharma
2014-05-15  7:42       ` Thierry Reding
2014-05-15  8:17         ` Rahul Sharma
2014-05-15  9:23           ` Thierry Reding
2014-05-15 13:31   ` Bartlomiej Zolnierkiewicz
2014-05-15 13:35     ` Rahul Sharma
2014-05-15 13:41       ` Kishon Vijay Abraham I
2014-05-15 13:45         ` Rahul Sharma
2014-05-14 19:17 ` [PATCH v3 2/3] drm: exynos: hdmi: use hdmiphy as PHY Rahul Sharma
2014-05-14 19:17 ` [PATCH v3 3/3] s5p-tv: " Rahul Sharma

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