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Message-ID: <61ff6865-41bb-85af-2fdd-ff80e3c2b67f@kontron.de>
Date:   Wed, 3 May 2023 17:18:40 +0200
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Subject: Re: [PATCH V3 2/7] drm: bridge: samsung-dsim: Fix PMS Calculator on
 imx8m[mnp]
Content-Language: en-US, de-DE
To:     Adam Ford <aford173@gmail.com>, dri-devel@lists.freedesktop.org
Cc:     marex@denx.de, aford@beaconembedded.com,
        Lucas Stach <l.stach@pengutronix.de>,
        Chen-Yu Tsai <wenst@chromium.org>,
        Andrzej Hajda <andrzej.hajda@intel.com>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Robert Foss <rfoss@kernel.org>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Inki Dae <inki.dae@samsung.com>,
        Jagan Teki <jagan@amarulasolutions.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        linux-kernel@vger.kernel.org
References: <20230502010759.17282-1-aford173@gmail.com>
 <20230502010759.17282-3-aford173@gmail.com>
From:   Frieder Schrempf <frieder.schrempf@kontron.de>
In-Reply-To: <20230502010759.17282-3-aford173@gmail.com>
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On 02.05.23 03:07, Adam Ford wrote:
> According to Table 13-45 of the i.MX8M Mini Reference Manual, the min
> and max values for M and the frequency range for the VCO_out
> calculator were incorrect.  This information was contradicted in other
> parts of the mini, nano and plus manuals.  After reaching out to my
> NXP Rep, when confronting him about discrepencies in the Nano manual,
> he responded with:
>  "Yes it is definitely wrong, the one that is part
>   of the NOTE in MIPI_DPHY_M_PLLPMS register table against PMS_P,
>   PMS_M and PMS_S is not correct. I will report this to Doc team,
>   the one customer should be take into account is the Table 13-40
>   DPHY PLL Parameters and the Note above."
> 
> These updated values also match what is used in the NXP downstream
> kernel.
> 
> To fix this, make new variables to hold the min and max values of m
> and the minimum value of VCO_out, and update the PMS calculator to
> use these new variables instead of using hard-coded values to keep
> the backwards compatibility with other parts using this driver.
> 
> Fixes: 4d562c70c4dc ("drm: bridge: samsung-dsim: Add i.MX8M Mini/Nano support")
> Signed-off-by: Adam Ford <aford173@gmail.com>
> Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
> Tested-by: Chen-Yu Tsai <wenst@chromium.org>

Tested on Kontron BL i.MX8MM with SN65DSI84 and ADV7535 bridges.

Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>