Re: [PATCH v2 4.1/5] drm/i915: calculate the port clock rate along with other PLL params

Ville Syrjälä
2015-06-24T12:53:35Z

On Mon, Jun 22, 2015 at 11:35:51PM +0300, Imre Deak wrote:
> Depending on the platform the port clock fed to the pipe can be the PLL's
> post-divided fast clock rate or a /5 divided version of it. To make this
> more obvious across the platforms calculate this port clock along with
> the rest of the PLL parameters.
>
> This is also needed by the next patch where we can reuse the CHV helper
> for the BXT PLL HW readout code; so export the corresponding helper.
>
> While at it also add a more descriptive name to the helpers and a
> comment explaining what's being calculated.
>
> No functional change.
>
> Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>

I'm not sure I entirely like the new name, but the old name wasn't
good either, and I can't think of anything better.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
> drivers/gpu/drm/i915/intel_display.c | 61 +++++++++++++++++++++---------------
> drivers/gpu/drm/i915/intel_drv.h | 2 ++
> 2 files changed, 38 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index fb7fd5f..a11ce7fa 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -553,15 +553,25 @@ intel_limit(struct intel_crtc_state *crtc_state, int refclk)
> return limit;
> }
>
> +/*
> + * Platform specific helpers to calculate the port PLL loopback- (clock.m),
> + * and post-divider (clock.p) values, pre- (clock.vco) and post-divided fast
> + * (clock.dot) clock rates. This fast dot clock is fed to the port's IO logic.
> + * The helpers' return value is the rate of the clock that is fed to the
> + * display engine's pipe which can be the above fast dot clock rate or a
> + * divided-down version of it.
> + */
> /* m1 is reserved as 0 in Pineview, n is a ring counter */
> -static void pineview_clock(int refclk, intel_clock_t *clock)
> +static int pnv_calc_dpll_params(int refclk, intel_clock_t *clock)
> {
> clock->m = clock->m2 + 2;
> clock->p = clock->p1 * clock->p2;
> if (WARN_ON(clock->n == 0 || clock->p == 0))
> - return;
> + return 0;
> clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
> clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
> +
> + return clock->dot;
> }
>
> static uint32_t i9xx_dpll_compute_m(struct dpll *dpll)
> @@ -569,35 +579,41 @@ static uint32_t i9xx_dpll_compute_m(struct dpll *dpll)
> return 5 * (dpll->m1 + 2) + (dpll->m2 + 2);
> }
>
> -static void i9xx_clock(int refclk, intel_clock_t *clock)
> +static int i9xx_calc_dpll_params(int refclk, intel_clock_t *clock)
> {
> clock->m = i9xx_dpll_compute_m(clock);
> clock->p = clock->p1 * clock->p2;
> if (WARN_ON(clock->n + 2 == 0 || clock->p == 0))
> - return;
> + return 0;
> clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n + 2);
> clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
> +
> + return clock->dot;
> }
>
> -static void vlv_clock(int refclk, intel_clock_t *clock)
> +static int vlv_calc_dpll_params(int refclk, intel_clock_t *clock)
> {
> clock->m = clock->m1 * clock->m2;
> clock->p = clock->p1 * clock->p2;
> if (WARN_ON(clock->n == 0 || clock->p == 0))
> - return;
> + return 0;
> clock->vco = DIV_ROUND_CLOSEST(refclk * clock->m, clock->n);
> clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
> +
> + return clock->dot / 5;
> }
>
> -static void chv_clock(int refclk, intel_clock_t *clock)
> +int chv_calc_dpll_params(int refclk, intel_clock_t *clock)
> {
> clock->m = clock->m1 * clock->m2;
> clock->p = clock->p1 * clock->p2;
> if (WARN_ON(clock->n == 0 || clock->p == 0))
> - return;
> + return 0;
> clock->vco = DIV_ROUND_CLOSEST_ULL((uint64_t)refclk * clock->m,
> clock->n << 22);
> clock->dot = DIV_ROUND_CLOSEST(clock->vco, clock->p);
> +
> + return clock->dot / 5;
> }
>
> #define INTELPllInvalid(s) do { /* DRM_DEBUG(s); */ return false; } while (0)
> @@ -692,7 +708,7 @@ i9xx_find_best_dpll(const intel_limit_t *limit,
> clock.p1 <= limit->p1.max; clock.p1++) {
> int this_err;
>
> - i9xx_clock(refclk, &clock);
> + i9xx_calc_dpll_params(refclk, &clock);
> if (!intel_PLL_is_valid(dev, limit,
> &clock))
> continue;
> @@ -737,7 +753,7 @@ pnv_find_best_dpll(const intel_limit_t *limit,
> clock.p1 <= limit->p1.max; clock.p1++) {
> int this_err;
>
> - pineview_clock(refclk, &clock);
> + pnv_calc_dpll_params(refclk, &clock);
> if (!intel_PLL_is_valid(dev, limit,
> &clock))
> continue;
> @@ -787,7 +803,7 @@ g4x_find_best_dpll(const intel_limit_t *limit,
> clock.p1 >= limit->p1.min; clock.p1--) {
> int this_err;
>
> - i9xx_clock(refclk, &clock);
> + i9xx_calc_dpll_params(refclk, &clock);
> if (!intel_PLL_is_valid(dev, limit,
> &clock))
> continue;
> @@ -877,7 +893,7 @@ vlv_find_best_dpll(const intel_limit_t *limit,
> clock.m2 = DIV_ROUND_CLOSEST(target * clock.p * clock.n,
> refclk * clock.m1);
>
> - vlv_clock(refclk, &clock);
> + vlv_calc_dpll_params(refclk, &clock);
>
> if (!intel_PLL_is_valid(dev, limit,
> &clock))
> @@ -940,7 +956,7 @@ chv_find_best_dpll(const intel_limit_t *limit,
>
> clock.m2 = m2;
>
> - chv_clock(refclk, &clock);
> + chv_calc_dpll_params(refclk, &clock);
>
> if (!intel_PLL_is_valid(dev, limit, &clock))
> continue;
> @@ -7926,10 +7942,7 @@ static void vlv_crtc_clock_get(struct intel_crtc *crtc,
> clock.p1 = (mdiv >> DPIO_P1_SHIFT) & 7;
> clock.p2 = (mdiv >> DPIO_P2_SHIFT) & 0x1f;
>
> - vlv_clock(refclk, &clock);
> -
> - /* clock.dot is the fast clock */
> - pipe_config->port_clock = clock.dot / 5;
> + pipe_config->port_clock = vlv_calc_dpll_params(refclk, &clock);
> }
>
> static void
> @@ -8025,10 +8038,7 @@ static void chv_crtc_clock_get(struct intel_crtc *crtc,
> clock.p1 = (cmn_dw13 >> DPIO_CHV_P1_DIV_SHIFT) & 0x7;
> clock.p2 = (cmn_dw13 >> DPIO_CHV_P2_DIV_SHIFT) & 0x1f;
>
> - chv_clock(refclk, &clock);
> -
> - /* clock.dot is the fast clock */
> - pipe_config->port_clock = clock.dot / 5;
> + pipe_config->port_clock = chv_calc_dpll_params(refclk, &clock);
> }
>
> static bool i9xx_get_pipe_config(struct intel_crtc *crtc,
> @@ -10481,6 +10491,7 @@ static void i9xx_crtc_clock_get(struct intel_crtc *crtc,
> u32 dpll = pipe_config->dpll_hw_state.dpll;
> u32 fp;
> intel_clock_t clock;
> + int port_clock;
> int refclk = i9xx_pll_refclk(dev, pipe_config);
>
> if ((dpll & DISPLAY_RATE_SELECT_FPA1) == 0)
> @@ -10521,9 +10532,9 @@ static void i9xx_crtc_clock_get(struct intel_crtc *crtc,
> }
>
> if (IS_PINEVIEW(dev))
> - pineview_clock(refclk, &clock);
> + port_clock = pnv_calc_dpll_params(refclk, &clock);
> else
> - i9xx_clock(refclk, &clock);
> + port_clock = i9xx_calc_dpll_params(refclk, &clock);
> } else {
> u32 lvds = IS_I830(dev) ? 0 : I915_READ(LVDS);
> bool is_lvds = (pipe == 1) && (lvds & LVDS_PORT_EN);
> @@ -10549,7 +10560,7 @@ static void i9xx_crtc_clock_get(struct intel_crtc *crtc,
> clock.p2 = 2;
> }
>
> - i9xx_clock(refclk, &clock);
> + port_clock = i9xx_calc_dpll_params(refclk, &clock);
> }
>
> /*
> @@ -10557,7 +10568,7 @@ static void i9xx_crtc_clock_get(struct intel_crtc *crtc,
> * port_clock to compute adjusted_mode.crtc_clock in the
> * encoder's get_config() function.
> */
> - pipe_config->port_clock = clock.dot;
> + pipe_config->port_clock = port_clock;
> }
>
> int intel_dotclock_calculate(int link_freq,
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index e2174fd..7a5b3bc 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1138,6 +1138,8 @@ ironlake_check_encoder_dotclock(const struct intel_crtc_state *pipe_config,
> int dotclock);
> bool bxt_find_best_dpll(struct intel_crtc_state *crtc_state, int target_clock,
> intel_clock_t *best_clock);
> +int chv_calc_dpll_params(int refclk, intel_clock_t *pll_clock);
> +
> bool intel_crtc_active(struct drm_crtc *crtc);
> void hsw_enable_ips(struct intel_crtc *crtc);
> void hsw_disable_ips(struct intel_crtc *crtc);
> --
> 2.1.4

--
Ville Syrjälä
Intel OTC