linux-kernel - Re: [PATCH 34/49] media: tegra-video: replace bitmap_weight with bitmap_weight

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Date:   Thu, 28 Apr 2022 09:31:15 +0200
From:   Hans Verkuil <hverkuil-cisco@...all.nl>
To:     Yury Norov <yury.norov@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        David Laight <David.Laight@...lab.com>,
        Joe Perches <joe@...ches.com>, Dennis Zhou <dennis@...nel.org>,
        Emil Renner Berthing <kernel@...il.dk>,
        Nicholas Piggin <npiggin@...il.com>,
        Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
        Alexey Klimov <aklimov@...hat.com>,
        linux-kernel@...r.kernel.org,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Sowjanya Komatineni <skomatineni@...dia.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-staging@...ts.linux.dev
Subject: Re: [PATCH 34/49] media: tegra-video: replace bitmap_weight with
 bitmap_weight_le

On 10/02/2022 23:49, Yury Norov wrote:
> tegra_channel_enum_format() calls bitmap_weight() to compare the weight
> of bitmap with a given number. We can do it more efficiently with
> bitmap_weight_le() because conditional bitmap_weight may stop traversing
> the bitmap earlier, as soon as condition is (or can't be) met.
> 
> Signed-off-by: Yury Norov <yury.norov@...il.com>

Acked-by: Hans Verkuil <hverkuil-cisco@...all.nl>

Regards,

	Hans

> ---
>  drivers/staging/media/tegra-video/vi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/media/tegra-video/vi.c b/drivers/staging/media/tegra-video/vi.c
> index d1f43f465c22..4e79a80e9307 100644
> --- a/drivers/staging/media/tegra-video/vi.c
> +++ b/drivers/staging/media/tegra-video/vi.c
> @@ -436,7 +436,7 @@ static int tegra_channel_enum_format(struct file *file, void *fh,
>  	if (!IS_ENABLED(CONFIG_VIDEO_TEGRA_TPG))
>  		fmts_bitmap = chan->fmts_bitmap;
>  
> -	if (f->index >= bitmap_weight(fmts_bitmap, MAX_FORMAT_NUM))
> +	if (bitmap_weight_le(fmts_bitmap, MAX_FORMAT_NUM, f->index))
>  		return -EINVAL;
>  
>  	for (i = 0; i < f->index + 1; i++, index++)