linux-kernel - Re: [PATCH v2 3/7] drm/msm/dsi: Use DIV_ROUND_UP instead of conditional increment on modulo

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Message-ID: <ec1a7af7-e9c9-9c62-040a-b12f0095da2b@quicinc.com>
Date:   Wed, 5 Oct 2022 14:34:53 -0700
From:   Abhinav Kumar <quic_abhinavk@...cinc.com>
To:     Marijn Suijten <marijn.suijten@...ainline.org>,
        <phone-devel@...r.kernel.org>, Rob Clark <robdclark@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Vinod Koul <vkoul@...nel.org>
CC:     <~postmarketos/upstreaming@...ts.sr.ht>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Martin Botka <martin.botka@...ainline.org>,
        Jami Kettunen <jami.kettunen@...ainline.org>,
        Daniel Vetter <daniel@...ll.ch>, Sean Paul <sean@...rly.run>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Alex Deucher <alexander.deucher@....com>,
        Douglas Anderson <dianders@...omium.org>,
        Vladimir Lypak <vladimir.lypak@...il.com>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <freedreno@...ts.freedesktop.org>,
        David Airlie <airlied@...ux.ie>
Subject: Re: [PATCH v2 3/7] drm/msm/dsi: Use DIV_ROUND_UP instead of
 conditional increment on modulo



On 10/5/2022 11:16 AM, Marijn Suijten wrote:
> This exact same math is used to compute bytes_in_slice above in
> dsi_update_dsc_timing(), also used to fill slice_chunk_size.
> 
> Fixes: b9080324d6ca ("drm/msm/dsi: add support for dsc data")
> Signed-off-by: Marijn Suijten <marijn.suijten@...ainline.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
> ---
>   drivers/gpu/drm/msm/dsi/dsi_host.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index c746ed5d61f9..48c966375ffa 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -1829,9 +1829,7 @@ static int dsi_populate_dsc_params(struct drm_dsc_config *dsc)
>   	 * params are calculated
>   	 */
>   	groups_per_line = DIV_ROUND_UP(dsc->slice_width, 3);
> -	dsc->slice_chunk_size = dsc->slice_width * dsc->bits_per_pixel / 8;
> -	if ((dsc->slice_width * dsc->bits_per_pixel) % 8)
> -		dsc->slice_chunk_size++;
> +	dsc->slice_chunk_size = DIV_ROUND_UP(dsc->slice_width * dsc->bits_per_pixel, 8);
>   
>   	/* rbs-min */
>   	min_rate_buffer_size =  dsc->rc_model_size - dsc->initial_offset +