linux-kernel - Re: [PATCH] drm/stm: ltdc: remove clk_round

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Message-ID: <c84e4be5-ec3d-aa6a-9571-4c6d2877fa5f@st.com>
Date:   Fri, 10 May 2019 16:40:05 +0000
From:   Philippe CORNU <philippe.cornu@...com>
To:     Yannick FERTRE <yannick.fertre@...com>,
        Benjamin GAIGNARD <benjamin.gaignard@...com>,
        Vincent ABRIOU <vincent.abriou@...com>,
        "David Airlie" <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre TORGUE <alexandre.torgue@...com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/stm: ltdc: remove clk_round_rate comment

Dear Yannick,
Thank you for your patch,

In your patch, you have removed clk_disable() & clk_enable().
Could you please double confirm ?

thanks
Philippe :-)


On 5/10/19 5:03 PM, Yannick Fertré wrote:
> Clk_round_rate returns rounded clock without changing
> the hardware in any way.
> This function couldn't replace set_rate/get_rate calls.
> Todo comment has been removed & a new log inserted.
> 
> Signed-off-by: Yannick Fertré <yannick.fertre@...com>
> ---
>   drivers/gpu/drm/stm/ltdc.c | 10 +++-------
>   1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> index 97912e2..2f8aa2e 100644
> --- a/drivers/gpu/drm/stm/ltdc.c
> +++ b/drivers/gpu/drm/stm/ltdc.c
> @@ -507,20 +507,16 @@ static bool ltdc_crtc_mode_fixup(struct drm_crtc *crtc,
>   	struct ltdc_device *ldev = crtc_to_ltdc(crtc);
>   	int rate = mode->clock * 1000;
>   
> -	/*
> -	 * TODO clk_round_rate() does not work yet. When ready, it can
> -	 * be used instead of clk_set_rate() then clk_get_rate().
> -	 */
> -
> -	clk_disable(ldev->pixel_clk);
>   	if (clk_set_rate(ldev->pixel_clk, rate) < 0) {
>   		DRM_ERROR("Cannot set rate (%dHz) for pixel clk\n", rate);
>   		return false;
>   	}
> -	clk_enable(ldev->pixel_clk);
>   
>   	adjusted_mode->clock = clk_get_rate(ldev->pixel_clk) / 1000;
>   
> +	DRM_DEBUG_DRIVER("requested clock %dkHz, adjusted clock %dkHz\n",
> +			 mode->clock, adjusted_mode->clock);
> +
>   	return true;
>   }
>   
>