linux-kernel - Re: [PATCH V6 6/6] drm: bridge: samsung-dsim: Support non-burst mode

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Date:   Thu, 18 May 2023 17:37:09 +0530
From:   Jagan Teki <jagan@...rulasolutions.com>
To:     Adam Ford <aford173@...il.com>
Cc:     dri-devel@...ts.freedesktop.org, aford@...conembedded.com,
        Chen-Yu Tsai <wenst@...omium.org>,
        Frieder Schrempf <frieder.schrempf@...tron.de>,
        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>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Marek Vasut <marex@...x.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V6 6/6] drm: bridge: samsung-dsim: Support non-burst mode

On Tue, May 16, 2023 at 5:27 AM Adam Ford <aford173@...il.com> wrote:
>
> The high-speed clock is hard-coded to the burst-clock
> frequency specified in the device tree.  However, when
> using devices like certain bridge chips without burst mode
> and varying resolutions and refresh rates, it may be
> necessary to set the high-speed clock dynamically based
> on the desired pixel clock for the connected device.
>
> This also removes the need to set a clock speed from
> the device tree for non-burst mode operation, since the
> pixel clock rate is the rate requested from the attached
> device like a bridge chip.  This should have no impact
> for people using burst-mode and setting the burst clock
> rate is still required for those users.  If the burst
> clock is not present, change the error message to
> dev_info indicating the clock use the pixel clock.
>
> Signed-off-by: Adam Ford <aford173@...il.com>
> Tested-by: Chen-Yu Tsai <wenst@...omium.org>
> Tested-by: Frieder Schrempf <frieder.schrempf@...tron.de>
> Reviewed-by: Frieder Schrempf <frieder.schrempf@...tron.de>
> ---
>  drivers/gpu/drm/bridge/samsung-dsim.c | 27 +++++++++++++++++++++------
>  1 file changed, 21 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
> index 3944b7cfbbdf..03b21d13f067 100644
> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> @@ -655,16 +655,28 @@ static unsigned long samsung_dsim_set_pll(struct samsung_dsim *dsi,
>
>         dsi->hs_clock = fout;
>
> +       dsi->hs_clock = fout;

I dropped this and tested it.

Reviewed-by: Jagan Teki <jagan@...rulasolutions.com>
Tested-by: Jagan Teki <jagan@...rulasolutions.com> # imx8mm-icore