From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Jani Nikula <jani.nikula@intel.com>
Cc: intel-gfx@lists.freedesktop.org,
Manasi Navare <manasi.d.navare@intel.com>
Subject: Re: [Intel-gfx] [PATCH v2] drm/i915/dp: fix integer overflow in 128b/132b data rate calculation
Date: Tue, 26 Oct 2021 12:38:45 +0300 [thread overview]
Message-ID: <YXfMpUTtd9MwTsU3@intel.com> (raw)
In-Reply-To: <20211026093407.11381-1-jani.nikula@intel.com>
On Tue, Oct 26, 2021 at 12:34:07PM +0300, Jani Nikula wrote:
> The intermediate value 1000000 * 10 * 9671 overflows 32 bits, so force
> promotion to a bigger type.
>
> >From the logs:
>
> [drm:intel_dp_compute_config [i915]] DP link rate required 3657063 available -580783288
>
> v2: Use mul_u32_u32() (Ville)
>
> Fixes: 48efd014f0ea ("drm/i915/dp: add max data rate calculation for UHBR rates")
> Cc: Manasi Navare <manasi.d.navare@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_dp.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index f5dc2126d140..537c689a1528 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -352,7 +352,7 @@ intel_dp_max_data_rate(int max_link_rate, int max_lanes)
> */
> int max_link_rate_kbps = max_link_rate * 10;
>
> - max_link_rate_kbps = DIV_ROUND_CLOSEST_ULL(max_link_rate_kbps * 9671, 10000);
> + max_link_rate_kbps = DIV_ROUND_CLOSEST_ULL(mul_u32_u32(max_link_rate_kbps, 9671), 10000);
> max_link_rate = max_link_rate_kbps / 8;
> }
>
> --
> 2.30.2
--
Ville Syrjälä
Intel
next prev parent reply other threads:[~2021-10-26 9:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-26 8:42 [Intel-gfx] [PATCH] drm/i915/dp: fix integer overflow in 128b/132b data rate calculation Jani Nikula
2021-10-26 9:13 ` Ville Syrjälä
2021-10-26 9:34 ` [Intel-gfx] [PATCH v2] " Jani Nikula
2021-10-26 9:38 ` Ville Syrjälä [this message]
2021-10-26 16:05 ` Jani Nikula
2021-10-26 9:56 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for drm/i915/dp: fix integer overflow in 128b/132b data rate calculation (rev2) Patchwork
2021-10-26 10:30 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork
2021-10-26 11:53 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for drm/i915/dp: fix integer overflow in 128b/132b data rate calculation (rev3) Patchwork
2021-10-26 12:27 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2021-10-26 14:10 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork
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