linux-kernel - Re: [PATCH V3 0/7] drm: bridge: samsung-dsim: Support variable clocking

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Message-ID: <05fb14ea-1083-8efd-dad0-a0e707af8131@samsung.com>
Date:   Tue, 2 May 2023 10:35:31 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Adam Ford <aford173@...il.com>, dri-devel@...ts.freedesktop.org
Cc:     marex@...x.de, aford@...conembedded.com,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert Foss <rfoss@...nel.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Inki Dae <inki.dae@...sung.com>,
        Jagan Teki <jagan@...rulasolutions.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 0/7] drm: bridge: samsung-dsim: Support variable
 clocking

On 02.05.2023 03:07, Adam Ford wrote:
> This series fixes the blanking pack size and the PMS calculation.  It then
> adds support to allows the DSIM to dynamically DPHY clocks, and support
> non-burst mode while allowing the removal of the hard-coded clock values
> for the PLL for imx8m mini/nano/plus, and it allows the removal of the
> burst-clock device tree entry when burst-mode isn't supported by connected
> devices like an HDMI brige.  In that event, the HS clock is set to the value
> requested by the bridge chip.
>
> This has been tested on both an i.MX8M Nano and i.MX8M Plus, and should work
> on i.MX8M Mini as well.
>
> Adam Ford (6):
>    drm: bridge: samsung-dsim: Fix PMS Calculator on imx8m[mnp]
>    drm: bridge: samsung-dsim: Fetch pll-clock-frequency automatically
>    drm: bridge: samsung-dsim: Select GENERIC_PHY_MIPI_DPHY
>    drm: bridge: samsung-dsim: Dynamically configure DPHY timing
>    drm: bridge: samsung-dsim: Support non-burst mode
>    drm: bridge: samsung-dsim: Let blanking calcuation work in non-burst
>      mode
>
> Lucas Stach (1):
>    drm: bridge: samsung-dsim: fix blanking packet size calculation
>
>   drivers/gpu/drm/bridge/Kconfig        |   1 +
>   drivers/gpu/drm/bridge/samsung-dsim.c | 150 ++++++++++++++++++++++----
>   include/drm/bridge/samsung-dsim.h     |   5 +
>   3 files changed, 136 insertions(+), 20 deletions(-)

Works fine (= doesn't break) on Exynos.

Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>


>
> ---
> V3:  When checking if the bust-clock is present, only check for it
>       in the device tree, and don't check the presence of the
>       MIPI_DSI_MODE_VIDEO_BURST flag as it breaks an existing Exynos
>       board.
>       
>       Add a new patch to the series to select GENERIC_PHY_MIPI_DPHY in
>       Kconfig otherwise the build breaks on the 32-bit Exynos.
>       
>       Change vco_min variable name to min_freq
>
>       Added tested-by from Chen-Yu Tsai
>
> V2:  Instead of using my packet blanking calculation, this integrates
>       on from Lucas Stach which gets modified later in the series to
>       cache the value of the HS-clock instead of having to do the
>       calucations again.
>
>       Instead of completely eliminating the PLL clock frequency from
>       the device tree, this makes it optional to avoid breaking some
>       Samsung devices.  When the samsung,pll-clock-frequency is not
>       found, it reads the value of the clock named "sclk_mipi"
>       This also maintains backwords compatibility with older device
>       trees.
>
>       This also changes the DPHY calcuation from a Look-up table,
>       a reverse engineered algorithm which uses
>       phy_mipi_dphy_get_default_config to determine the standard
>       nominal values and calculates the cycles necessary to update
>       the DPHY timings accordingly.
>       

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland