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Date:   Wed, 26 Jul 2023 09:21:50 +0800
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Subject: Re: [Intel-gfx] [PATCH v2] drm/i915/tv: avoid possible division by
 zero
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To:     Dan Carpenter <dan.carpenter@linaro.org>
Cc:     Andi Shyti <andi.shyti@linux.intel.com>,
        jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com,
        rodrigo.vivi@intel.com, tvrtko.ursulin@linux.intel.com,
        airlied@gmail.com, daniel@ffwll.ch, nathan@kernel.org,
        ndesaulniers@google.com, trix@redhat.com, andrzej.hajda@intel.com,
        intel-gfx@lists.freedesktop.org, llvm@lists.linux.dev,
        kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org, mripard@kernel.org
From:   Su Hui <suhui@nfschina.com>
In-Reply-To: <5d096bcf-c394-4dad-b307-3d7e33ab6e6f@kadam.mountain>
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On 2023/7/25 13:51, Dan Carpenter wrote:
> The reason why the first five attempts had bugs is because we are
> trying to write it in the most complicated way possible, shifting by
> logical not what?
Wonderful! Should I add your name as signed-of-by?
I will send a v3 patch later.
Really thanks for your help!

Su Hui

> regards,
> dan carpenter
>
> diff --git a/drivers/gpu/drm/i915/display/intel_tv.c b/drivers/gpu/drm/i915/display/intel_tv.c
> index 36b479b46b60..6997b6cb1df2 100644
> --- a/drivers/gpu/drm/i915/display/intel_tv.c
> +++ b/drivers/gpu/drm/i915/display/intel_tv.c
> @@ -988,7 +988,13 @@ intel_tv_mode_to_mode(struct drm_display_mode *mode,
>   		      const struct tv_mode *tv_mode,
>   		      int clock)
>   {
> -	mode->clock = clock / (tv_mode->oversample >> !tv_mode->progressive);
> +	int div = tv_mode->oversample;
> +
> +	if (!tv_mode->progressive)
> +		div >>= 1;
> +	if (div == 0)
> +		div = 1;
> +	mode->clock = clock / div;
>   
>   	/*
>   	 * tv_mode horizontal timings:
> @@ -1135,6 +1141,8 @@ intel_tv_get_config(struct intel_encoder *encoder,
>   		break;
>   	default:
>   		tv_mode.oversample = 1;
> +		WARN_ON_ONCE(!tv_mode.progressive);
> +		tv_mode.progressive = true;
>   		break;
>   	}
>   
>