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drm/nva3/clk: better pll calculation when no fractional fb div available
The core/mem/shader clocks don't support the fractional feedback divider, causing our calculated clocks to be off by quite a lot in some cases. To solve this we will switch to a search-based algorithm when fN is NULL. For my NVA8 at PL3, this actually generates identical cooefficients to the binary driver. Hopefully that's a good sign, and that does not break VPLL calculation for someone.. Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
This commit is contained in:
parent
96d1fcf8b5
commit
52eba8dd5e
4 changed files with 43 additions and 37 deletions
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@ -1353,7 +1353,7 @@ bool nv50_gpio_irq_enable(struct drm_device *, enum dcb_gpio_tag, bool on);
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/* nv50_calc. */
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int nv50_calc_pll(struct drm_device *, struct pll_lims *, int clk,
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int *N1, int *M1, int *N2, int *M2, int *P);
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int nv50_calc_pll2(struct drm_device *, struct pll_lims *,
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int nva3_calc_pll(struct drm_device *, struct pll_lims *,
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int clk, int *N, int *fN, int *M, int *P);
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#ifndef ioread32_native
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@ -23,7 +23,6 @@
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*/
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#include "drmP.h"
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#include "drm_fixed.h"
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#include "nouveau_drv.h"
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#include "nouveau_hw.h"
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@ -47,45 +46,52 @@ nv50_calc_pll(struct drm_device *dev, struct pll_lims *pll, int clk,
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}
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int
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nv50_calc_pll2(struct drm_device *dev, struct pll_lims *pll, int clk,
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int *N, int *fN, int *M, int *P)
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nva3_calc_pll(struct drm_device *dev, struct pll_lims *pll, int clk,
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int *pN, int *pfN, int *pM, int *P)
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{
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fixed20_12 fb_div, a, b;
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u32 refclk = pll->refclk / 10;
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u32 max_vco_freq = pll->vco1.maxfreq / 10;
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u32 max_vco_inputfreq = pll->vco1.max_inputfreq / 10;
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clk /= 10;
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u32 best_err = ~0, err;
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int M, lM, hM, N, fN;
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*P = max_vco_freq / clk;
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*P = pll->vco1.maxfreq / clk;
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if (*P > pll->max_p)
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*P = pll->max_p;
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if (*P < pll->min_p)
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*P = pll->min_p;
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/* *M = floor((refclk + max_vco_inputfreq) / max_vco_inputfreq); */
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a.full = dfixed_const(refclk + max_vco_inputfreq);
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b.full = dfixed_const(max_vco_inputfreq);
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a.full = dfixed_div(a, b);
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a.full = dfixed_floor(a);
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*M = dfixed_trunc(a);
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lM = (pll->refclk + pll->vco1.max_inputfreq) / pll->vco1.max_inputfreq;
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lM = max(lM, (int)pll->vco1.min_m);
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hM = (pll->refclk + pll->vco1.min_inputfreq) / pll->vco1.min_inputfreq;
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hM = min(hM, (int)pll->vco1.max_m);
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/* fb_div = (vco * *M) / refclk; */
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fb_div.full = dfixed_const(clk * *P);
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fb_div.full = dfixed_mul(fb_div, a);
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a.full = dfixed_const(refclk);
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fb_div.full = dfixed_div(fb_div, a);
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for (M = lM; M <= hM; M++) {
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u32 tmp = clk * *P * M;
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N = tmp / pll->refclk;
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fN = tmp % pll->refclk;
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if (!pfN && fN >= pll->refclk / 2)
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N++;
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/* *N = floor(fb_div); */
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a.full = dfixed_floor(fb_div);
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*N = dfixed_trunc(fb_div);
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if (N < pll->vco1.min_n)
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continue;
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if (N > pll->vco1.max_n)
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break;
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/* *fN = (fmod(fb_div, 1.0) * 8192) - 4096; */
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b.full = dfixed_const(8192);
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a.full = dfixed_mul(a, b);
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fb_div.full = dfixed_mul(fb_div, b);
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fb_div.full = fb_div.full - a.full;
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*fN = dfixed_trunc(fb_div) - 4096;
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*fN &= 0xffff;
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err = abs(clk - (pll->refclk * N / M / *P));
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if (err < best_err) {
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best_err = err;
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*pN = N;
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*pM = M;
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}
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if (pfN) {
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*pfN = (((fN << 13) / pll->refclk) - 4096) & 0xffff;
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return clk;
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}
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}
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if (unlikely(best_err == ~0)) {
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NV_ERROR(dev, "unable to find matching pll values\n");
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return -EINVAL;
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}
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return pll->refclk * *pN / *pM / *P;
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}
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@ -286,7 +286,7 @@ nv50_crtc_set_clock(struct drm_device *dev, int head, int pclk)
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nv_wr32(dev, pll.reg + 8, reg2 | (P << 28) | (M2 << 16) | N2);
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} else
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if (dev_priv->chipset < NV_C0) {
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ret = nv50_calc_pll2(dev, &pll, pclk, &N1, &N2, &M1, &P);
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ret = nva3_calc_pll(dev, &pll, pclk, &N1, &N2, &M1, &P);
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if (ret <= 0)
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return 0;
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@ -298,7 +298,7 @@ nv50_crtc_set_clock(struct drm_device *dev, int head, int pclk)
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nv_wr32(dev, pll.reg + 4, reg1 | (P << 16) | (M1 << 8) | N1);
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nv_wr32(dev, pll.reg + 8, N2);
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} else {
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ret = nv50_calc_pll2(dev, &pll, pclk, &N1, &N2, &M1, &P);
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ret = nva3_calc_pll(dev, &pll, pclk, &N1, &N2, &M1, &P);
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if (ret <= 0)
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return 0;
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@ -104,7 +104,7 @@ nva3_pm_clock_pre(struct drm_device *dev, struct nouveau_pm_level *perflvl,
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{
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struct nva3_pm_state *pll;
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struct pll_lims limits;
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int N, fN, M, P, diff;
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int N, M, P, diff;
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int ret, off;
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ret = get_pll_limits(dev, id, &limits);
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@ -136,7 +136,7 @@ nva3_pm_clock_pre(struct drm_device *dev, struct nouveau_pm_level *perflvl,
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}
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if (!pll->new_div) {
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ret = nv50_calc_pll2(dev, &limits, khz, &N, &fN, &M, &P);
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ret = nva3_calc_pll(dev, &limits, khz, &N, NULL, &M, &P);
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if (ret < 0)
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return ERR_PTR(ret);
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