Re: [PATCH 10/12] drm/i915: Allow rate_to_index() to return non-exact matches

Daniel Vetter
2016-07-29T09:35:33Z

On Thu, Jul 28, 2016 at 05:50:46PM +0300, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Let's make rate_to_index() return the highest rate available that's
> less than or equal to the rate requested by the caller. The function
> can then be used to filter out rates higher than a certain maximum
> rate.
>
> Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
> Cc: Jim Bride <jim.bride@linux.intel.com>
> Cc: Manasi D Navare <manasi.d.navare@intel.com>
> Cc: Durgadoss R <durgadoss.r@intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Not sure what this will be used for, couldn't figure it out looking at
later patches?
-Daneil

> ---
> drivers/gpu/drm/i915/intel_dp.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 40cae6202160..08d95352ffd6 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1431,10 +1431,13 @@ static int rate_to_index(int find, const int *rates)
> int i = 0;
>
> for (i = 0; i < DP_MAX_SUPPORTED_RATES; ++i)
> - if (find == rates[i])
> + if (find < rates[i])
> break;
>
> - return i;
> + if (WARN_ON(i == 0))
> + return 0;
> +
> + return i - 1;
> }
>
> int
> --
> 2.7.4
>
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--
Daniel Vetter
Software Engineer, Intel Corporation