linux-kernel - Re: [v2,03/10] drm/sun4i: Protect the TCON pixel clocks

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Message-ID: <7ed0fad9-6b3d-aafc-08a6-fb18761897aa@micronovasrl.com>
Date:   Sat, 24 Feb 2018 00:31:36 +0100
From:   Giulio Benetti <giulio.benetti@...ronovasrl.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>,
        Mark Brown <broonie@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [v2,03/10] drm/sun4i: Protect the TCON pixel clocks

Il 21/02/2018 10:20, Maxime Ripard ha scritto:
> From: Maxime Ripard <maxime.ripard@...e-electrons.com>
> 
> Both TCON clocks are very sensitive to clock changes, since any change
> might lead to improper timings.
> 
> Make sure our rate is never changed.
> 
> Signed-off-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
Tested-by: Giulio Benetti <giulio.benetti@...ronovasrl.com>

Tested on A20-LiNova1-4_3i-ctp with Mali r6p2 installed.
Before Mali changed dotclock, now it doesn't anymore.

> ---
>   drivers/gpu/drm/sun4i/sun4i_tcon.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> index b73acab74867..cbe87cee13d1 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -261,7 +261,7 @@ static void sun4i_tcon0_mode_set_common(struct sun4i_tcon *tcon,
>   					const struct drm_display_mode *mode)
>   {
>   	/* Configure the dot clock */
> -	clk_set_rate(tcon->dclk, mode->crtc_clock * 1000);
> +	clk_set_rate_exclusive(tcon->dclk, mode->crtc_clock * 1000);
>   
>   	/* Set the resolution */
>   	regmap_write(tcon->regs, SUN4I_TCON0_BASIC0_REG,
> @@ -419,7 +419,7 @@ static void sun4i_tcon1_mode_set(struct sun4i_tcon *tcon,
>   	WARN_ON(!tcon->quirks->has_channel_1);
>   
>   	/* Configure the dot clock */
> -	clk_set_rate(tcon->sclk1, mode->crtc_clock * 1000);
> +	clk_set_rate_exclusive(tcon->sclk1, mode->crtc_clock * 1000);
>   
>   	/* Adjust clock delay */
>   	clk_delay = sun4i_tcon_get_clk_delay(mode, 1);
>