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From:   Adam Ford <aford173@gmail.com>
Date:   Mon, 17 Apr 2023 06:53:07 -0500
Message-ID: <CAHCN7x+hFu15TM0w5DXzmWZRKEN6=MNNTVLNtpNxbirVGrapdg@mail.gmail.com>
Subject: Re: [PATCH 4/6] drm: bridge: samsung-dsim: Dynamically configure DPHY timing
To:     Lucas Stach <l.stach@pengutronix.de>
Cc:     dri-devel@lists.freedesktop.org,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        aford@beaconembedded.com,
        Frieder Schrempf <frieder.schrempf@kontron.de>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Andrzej Hajda <andrzej.hajda@intel.com>,
        Fabio Estevam <festevam@gmail.com>, m.szyprowski@samsung.com,
        marex@denx.de, Robert Foss <rfoss@kernel.org>,
        David Airlie <airlied@gmail.com>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Jagan Teki <jagan@amarulasolutions.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        devicetree@vger.kernel.org, Daniel Vetter <daniel@ffwll.ch>,
        Jonas Karlman <jonas@kwiboo.se>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Inki Dae <inki.dae@samsung.com>,
        Rob Herring <robh+dt@kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        Neil Armstrong <neil.armstrong@linaro.org>,
        linux-kernel@vger.kernel.org,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Shawn Guo <shawnguo@kernel.org>
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On Mon, Apr 17, 2023 at 3:38=E2=80=AFAM Lucas Stach <l.stach@pengutronix.de=
> wrote:
>
> Hi Adam,
>
> Am Samstag, dem 15.04.2023 um 05:41 -0500 schrieb Adam Ford:
> > NXP uses a lookup table to determine the various values for
> > the PHY Timing based on the clock rate in their downstream
> > kernel.  Since the input clock can be variable, the phy
> > settings need to be variable too.  Add an additional variable
> > to the driver data to enable this feature to prevent breaking
> > boards that don't support it.
> >
>
> I haven't checked if this generates values close to the ones in this
> table, but I guess it should be worth a try to use
> phy_mipi_dphy_get_default_config() instead.

I didn't know that was a thing.  I like that idea much better than the
table.  I just pulled what NXP had and tweaked it to fit the mainline.
I'll give it a try in the next few days, when I have some more time.

adam
>
> Regards,
> Lucas
>
> > Signed-off-by: Adam Ford <aford173@gmail.com>
> > ---
> >  drivers/gpu/drm/bridge/samsung-dsim.c |  85 +++++++--
> >  drivers/gpu/drm/bridge/samsung-dsim.h | 254 ++++++++++++++++++++++++++
> >  include/drm/bridge/samsung-dsim.h     |   1 +
> >  3 files changed, 326 insertions(+), 14 deletions(-)
> >  create mode 100644 drivers/gpu/drm/bridge/samsung-dsim.h
> >
<snip>
>