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Subject: Re: [PATCH v5 0/9] phy: Add configuration interface for MIPI D-PHY
 devices
To:     Maxime Ripard <maxime.ripard@bootlin.com>
CC:     Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        <linux-media@vger.kernel.org>,
        Archit Taneja <architt@codeaurora.org>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Chen-Yu Tsai <wens@csie.org>, <linux-kernel@vger.kernel.org>,
        <dri-devel@lists.freedesktop.org>,
        <linux-arm-kernel@lists.infradead.org>,
        Krzysztof Witos <kwitos@cadence.com>,
        Rafal Ciepiela <rafalc@cadence.com>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Sean Paul <seanpaul@chromium.org>
References: <cover.fbf0776c70c0cfb7b7fd88ce6a96b4597d620cac.1548085432.git-series.maxime.ripard@bootlin.com>
From:   Kishon Vijay Abraham I <kishon@ti.com>
Message-ID: <fc5427d3-674e-cebc-99b9-11493f976a20@ti.com>
Date:   Mon, 4 Feb 2019 15:33:31 +0530
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On 21/01/19 9:15 PM, Maxime Ripard wrote:
> Hi,
> 
> Here is a set of patches to allow the phy framework consumers to test and
> apply runtime configurations.
> 
> This is needed to support more phy classes that require tuning based on
> parameters depending on the current use case of the device, in addition to
> the power state management already provided by the current functions.
> 
> A first test bed for that API are the MIPI D-PHY devices. There's a number
> of solutions that have been used so far to support these phy, most of the
> time being an ad-hoc driver in the consumer.
> 
> That approach has a big shortcoming though, which is that this is quite
> difficult to deal with consumers integrated with multiple variants of phy,
> of multiple consumers integrated with the same phy.
> 
> The latter case can be found in the Cadence DSI bridge, and the CSI
> transceiver and receivers. All of them are integrated with the same phy, or
> can be integrated with different phy, depending on the implementation.
> 
> I've looked at all the MIPI DSI drivers I could find, and gathered all the
> parameters I could find. The interface should be complete, and most of the
> drivers can be converted in the future. The current set converts two of
> them: the above mentionned Cadence DSI driver so that the v4l2 drivers can
> use them, and the Allwinner MIPI-DSI driver.

Can the PHY changes go independently of the consumer drivers? or else I'll need
ACKs from the GPU MAINTAINER.

Thanks
Kishon

> 
> Let me know what you think,
> Maxime
> 
> Changes from v4:
>   - Removed regression on the variable calculation
>   - Fixed the wakeup unit
>   - Collected Sean Acked-by on the last patch
>   - Collected Sakari Reviewed-by on the first patch
> 
> Changes from v3
>   - Rebased on 5.0-rc1
>   - Added the fixes suggested by Sakari
> 
> Changes from v2:
>   - Rebased on next
>   - Changed the interface to accomodate for the new submodes
>   - Changed the timings units from nanoseconds to picoseconds
>   - Added minimum and maximum boundaries to the documentation
>   - Moved the clock enabling to phy_power_on in the Cadence DPHY driver
>   - Exported the phy_configure and phy_validate symbols
>   - Rework the phy pll divider computation in the cadence dphy driver
> 
> Changes from v1:
>   - Rebased on top of 4.20-rc1
>   - Removed the bus mode and timings parameters from the MIPI D-PHY
>     parameters, since that shouldn't have any impact on the PHY itself.
>   - Reworked the Cadence DSI and D-PHY drivers to take this into account.
>   - Remove the mode parameter from phy_configure
>   - Added phy_configure and phy_validate stubs
>   - Return -EOPNOTSUPP in phy_configure and phy_validate when the operation
>     is not implemented
> 
> Maxime Ripard (9):
>   phy: dphy: Remove unused header
>   phy: dphy: Change units of wakeup and init parameters
>   phy: dphy: Clarify lanes parameter documentation
>   sun6i: dsi: Convert to generic phy handling
>   phy: Move Allwinner A31 D-PHY driver to drivers/phy/
>   drm/bridge: cdns: Separate DSI and D-PHY configuration
>   dt-bindings: phy: Move the Cadence D-PHY bindings
>   phy: Add Cadence D-PHY support
>   drm/bridge: cdns: Convert to phy framework
> 
>  Documentation/devicetree/bindings/display/bridge/cdns,dsi.txt |  21 +-
>  Documentation/devicetree/bindings/phy/cdns,dphy.txt           |  20 +-
>  drivers/gpu/drm/bridge/Kconfig                                |   1 +-
>  drivers/gpu/drm/bridge/cdns-dsi.c                             | 538 +------
>  drivers/gpu/drm/sun4i/Kconfig                                 |   3 +-
>  drivers/gpu/drm/sun4i/Makefile                                |   5 +-
>  drivers/gpu/drm/sun4i/sun6i_mipi_dphy.c                       | 292 +----
>  drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c                        |  31 +-
>  drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h                        |  17 +-
>  drivers/phy/allwinner/Kconfig                                 |  12 +-
>  drivers/phy/allwinner/Makefile                                |   1 +-
>  drivers/phy/allwinner/phy-sun6i-mipi-dphy.c                   | 318 ++++-
>  drivers/phy/cadence/Kconfig                                   |  13 +-
>  drivers/phy/cadence/Makefile                                  |   1 +-
>  drivers/phy/cadence/cdns-dphy.c                               | 389 +++++-
>  drivers/phy/phy-core-mipi-dphy.c                              |   8 +-
>  include/linux/phy/phy-mipi-dphy.h                             |  13 +-
>  17 files changed, 894 insertions(+), 789 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/phy/cdns,dphy.txt
>  delete mode 100644 drivers/gpu/drm/sun4i/sun6i_mipi_dphy.c
>  create mode 100644 drivers/phy/allwinner/phy-sun6i-mipi-dphy.c
>  create mode 100644 drivers/phy/cadence/cdns-dphy.c
> 
> base-commit: bfeffd155283772bbe78c6a05dec7c0128ee500c
>