From: Mika Kahola Date: Wed, 19 May 2021 00:06:18 +0000 (-0700) Subject: drm/i915/adl_p: Tx escape clock with DSI X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=510b2814889141656ec9aace9058165403894858;p=linux.git drm/i915/adl_p: Tx escape clock with DSI Today when the DSI controller is paired with the Combo-PHY it uses the high-speed (HS) Word clock for its low power (LP) transmit PPI communication to the DPHY. The interface signaling only changes state at an Escape clock frequency (i.e. its effectively running on a virtual Tx Escape clock that is controlled by counters w/in the controller), but all the interface flops are running off the HS clock. This has the following drawbacks: * It is a deviation from the PPI spec which assumes signaling is running on a physical Escape clock * The PV timings are over constrained (HS timed to 312.5MHz vs. an Escape clock of 20MHz max) This feature is proposing to change the LP Tx communication between the controller and the DPHY from a virtual Tx Escape clock to a physical clock. To do this we need to program two "M" divisors. One for the usual DSI_ESC_CLK_DIV and DPHY_ESC_CLK_DIV register and one for MIPIO_DWORD8. For DSI_ESC_CLK_DIV and DPHY_ESC_CLK_DIV registers the "M" is calculated as following Nt = ceil(f_link/160) (theoretical word clock) Nact = max[3, Nt + (Nt + 1)%2] (actual word clock) M = Nact * 8 For MIPIO_DWORD8 register, the divisor "M" is calculated as following M = (Nact - 1)/2 BSpec: 55171 Cc: Vandita Kulkarni Signed-off-by: Mika Kahola Signed-off-by: Clinton Taylor Signed-off-by: Matt Roper Reviewed-by: Vandita Kulkarni Signed-off-by: Lucas De Marchi Link: https://patchwork.freedesktop.org/patch/msgid/20210519000625.3184321-11-lucas.demarchi@intel.com --- diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c index ce544e20f35c4..16812488c5ddc 100644 --- a/drivers/gpu/drm/i915/display/icl_dsi.c +++ b/drivers/gpu/drm/i915/display/icl_dsi.c @@ -363,10 +363,19 @@ static void gen11_dsi_program_esc_clk_div(struct intel_encoder *encoder, struct intel_dsi *intel_dsi = enc_to_intel_dsi(encoder); enum port port; int afe_clk_khz; - u32 esc_clk_div_m; + int theo_word_clk, act_word_clk; + u32 esc_clk_div_m, esc_clk_div_m_phy; afe_clk_khz = afe_clk(encoder, crtc_state); - esc_clk_div_m = DIV_ROUND_UP(afe_clk_khz, DSI_MAX_ESC_CLK); + + if (IS_ALDERLAKE_S(dev_priv) || IS_ALDERLAKE_P(dev_priv)) { + theo_word_clk = DIV_ROUND_UP(afe_clk_khz, 8 * DSI_MAX_ESC_CLK); + act_word_clk = max(3, theo_word_clk + (theo_word_clk + 1) % 2); + esc_clk_div_m = act_word_clk * 8; + esc_clk_div_m_phy = (act_word_clk - 1) / 2; + } else { + esc_clk_div_m = DIV_ROUND_UP(afe_clk_khz, DSI_MAX_ESC_CLK); + } for_each_dsi_port(port, intel_dsi->ports) { intel_de_write(dev_priv, ICL_DSI_ESC_CLK_DIV(port), @@ -379,6 +388,14 @@ static void gen11_dsi_program_esc_clk_div(struct intel_encoder *encoder, esc_clk_div_m & ICL_ESC_CLK_DIV_MASK); intel_de_posting_read(dev_priv, ICL_DPHY_ESC_CLK_DIV(port)); } + + if (IS_ALDERLAKE_S(dev_priv) || IS_ALDERLAKE_P(dev_priv)) { + for_each_dsi_port(port, intel_dsi->ports) { + intel_de_write(dev_priv, ADL_MIPIO_DW(port, 8), + esc_clk_div_m_phy & TX_ESC_CLK_DIV_PHY); + intel_de_posting_read(dev_priv, ADL_MIPIO_DW(port, 8)); + } + } } static void get_dsi_io_power_domains(struct drm_i915_private *dev_priv, diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h index 649b733d27fcf..7d8c11b7ff3ee 100644 --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -11319,6 +11319,12 @@ enum skl_power_gate { #define ICL_ESC_CLK_DIV_SHIFT 0 #define DSI_MAX_ESC_CLK 20000 /* in KHz */ +#define _ADL_MIPIO_REG 0x180 +#define ADL_MIPIO_DW(port, dw) _MMIO(_ICL_COMBOPHY(port) + _ADL_MIPIO_REG + 4 * (dw)) +#define TX_ESC_CLK_DIV_PHY_SEL REGBIT(16) +#define TX_ESC_CLK_DIV_PHY_MASK REG_GENMASK(23, 16) +#define TX_ESC_CLK_DIV_PHY REG_FIELD_PREP(TX_ESC_CLK_DIV_PHY_MASK, 0x7f) + #define _DSI_CMD_FRMCTL_0 0x6b034 #define _DSI_CMD_FRMCTL_1 0x6b834 #define DSI_CMD_FRMCTL(port) _MMIO_PORT(port, \