On Tue, 5 Nov 2013 22:42:28 +0200
ville.syrjala@xxxxxxxxxxxxxxx wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> We're currently miscalculating the VLV graphics clock a little bit.
> This is caused by rounding the step to integer MHz, which does not
> match reality. Change the formula to match the GUnit HAS to give
> more accurate answers.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_pm.c | 35 ++++++++++++-----------------------
> 1 file changed, 12 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index a5778e5..865035b 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5947,57 +5947,46 @@ int sandybridge_pcode_write(struct drm_i915_private *dev_priv, u8 mbox, u32 val)
>
> int vlv_gpu_freq(int ddr_freq, int val)
> {
> - int mult, base;
> + int div;
>
> + /* 4 x czclk */
> switch (ddr_freq) {
> case 800:
> - mult = 20;
> - base = 120;
> + div = 10;
> break;
> case 1066:
> - mult = 22;
> - base = 133;
> + div = 12;
> break;
> case 1333:
> - mult = 21;
> - base = 125;
> + div = 16;
> break;
> default:
> return -1;
> }
>
> - return ((val - 0xbd) * mult) + base;
> + return DIV_ROUND_CLOSEST(ddr_freq * (val + 6 - 0xbd), 4 * div);
> }
>
> int vlv_freq_opcode(int ddr_freq, int val)
> {
> - int mult, base;
> + int mul;
>
> + /* 4 x czclk */
> switch (ddr_freq) {
> case 800:
> - mult = 20;
> - base = 120;
> + mul = 10;
> break;
> case 1066:
> - mult = 22;
> - base = 133;
> + mul = 12;
> break;
> case 1333:
> - mult = 21;
> - base = 125;
> + mul = 16;
> break;
> default:
> return -1;
> }
>
> - val /= mult;
> - val -= base / mult;
> - val += 0xbd;
> -
> - if (val > 0xea)
> - val = 0xea;
> -
> - return val;
> + return DIV_ROUND_CLOSEST(4 * mul * val, ddr_freq) + 0xbd - 6;
> }
>
> void intel_pm_init(struct drm_device *dev)
Yeah these values look better at 1066 and 1333. No differences at 800
though.
Reviewed-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
--
Jesse Barnes, Intel Open Source Technology Center
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