This should be 1/2. this patch is required for "radeon kms: enable
frac fb divs on rs600/rs690/rs740"
On Mon, Jul 13, 2009 at 11:08 AM, Alex Deucher<alexdeuc...@gmail.com> wrote:
> This is needed when using fractional feedback dividers on some IGP
> chips.
>
> Signed-off-by: Alex Deucher <alexdeuc...@gmail.com>
> ---
> drivers/gpu/drm/radeon/radeon_display.c | 6 +++++-
> drivers/gpu/drm/radeon/radeon_mode.h | 1 +
> 2 files changed, 6 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_display.c
> b/drivers/gpu/drm/radeon/radeon_display.c
> index 3efcf1a..bc312f3 100644
> --- a/drivers/gpu/drm/radeon/radeon_display.c
> +++ b/drivers/gpu/drm/radeon/radeon_display.c
> @@ -491,7 +491,11 @@ void radeon_compute_pll(struct radeon_pll *pll,
> tmp += (uint64_t)pll->reference_freq *
> 1000 * frac_feedback_div;
> current_freq = radeon_div(tmp, ref_div
> * post_div);
>
> - error = abs(current_freq - freq);
> + if (flags &
> RADEON_PLL_PREFER_CLOSEST_LOWER) {
> + error = freq - current_freq;
> + error = error < 0 ?
> 0xffffffff : error;
> + } else
> + error = abs(current_freq -
> freq);
> vco_diff = abs(vco - best_vco);
>
> if ((best_vco == 0 && error <
> best_error) ||
> diff --git a/drivers/gpu/drm/radeon/radeon_mode.h
> b/drivers/gpu/drm/radeon/radeon_mode.h
> index 9173b68..e9b95ed 100644
> --- a/drivers/gpu/drm/radeon/radeon_mode.h
> +++ b/drivers/gpu/drm/radeon/radeon_mode.h
> @@ -124,6 +124,7 @@ struct radeon_tmds_pll {
> #define RADEON_PLL_PREFER_LOW_POST_DIV (1 << 8)
> #define RADEON_PLL_PREFER_HIGH_POST_DIV (1 << 9)
> #define RADEON_PLL_USE_FRAC_FB_DIV (1 << 10)
> +#define RADEON_PLL_PREFER_CLOSEST_LOWER (1 << 11)
>
> struct radeon_pll {
> uint16_t reference_freq;
> --
> 1.5.6.3
>
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