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commit 3de8da2ef12bacf3a20ab83c348ac2a679ba1333
parent c726bc7dca967177f00e141087282f7f03e22d1d
Author: Leah Rowe <info@minifree.org>
Date:   Thu,  8 Sep 2016 23:02:48 +0100

Fix low-res screens on T60 (patch from Arthur Heymans)

Diffstat:
resources/libreboot/patch/coreboot/2a3434757ef425dbdfedf1fc69e1a033a6e7310d/grub/t60/0003-i945-gma.c-use-latest-linux-code-to-calculate-diviso.patch | 174+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 174 insertions(+), 0 deletions(-)

diff --git a/resources/libreboot/patch/coreboot/2a3434757ef425dbdfedf1fc69e1a033a6e7310d/grub/t60/0003-i945-gma.c-use-latest-linux-code-to-calculate-diviso.patch b/resources/libreboot/patch/coreboot/2a3434757ef425dbdfedf1fc69e1a033a6e7310d/grub/t60/0003-i945-gma.c-use-latest-linux-code-to-calculate-diviso.patch @@ -0,0 +1,174 @@ +From 34f8cdbc30f1fdf4700c73aad26e0fc159af70ab Mon Sep 17 00:00:00 2001 +From: Arthur Heymans <arthur@aheymans.xyz> +Date: Fri, 2 Sep 2016 22:35:32 +0200 +Subject: [PATCH] i945/gma.c use latest linux code to calculate divisors. + +The code to compute n, m1, m2, p1 divisors is not correct in coreboot and +on some targets hits a working mode at lower refresh rate, which is why +display is working on some targets. +This patch also fixes reference frequency. + +This patch reuses linux code to correctly compute divisors. + +The result is that some previously not working displays (Lenovo T60 with +1024x786, 1400x1050, 2048x1536) + +TESTED on T60 with 1024x786. + +Change-Id: I2c7f3bb0024ac005029eaebe3ecdc70c38ac777e +Signed-off-by: Arthur Heymans <arthur@aheymans.xyz> +--- + src/northbridge/intel/i945/gma.c | 82 +++++++++++++++++++--------------------- + 1 file changed, 38 insertions(+), 44 deletions(-) + +diff --git a/src/northbridge/intel/i945/gma.c b/src/northbridge/intel/i945/gma.c +index 02caa0a..3f0b5b4 100644 +--- a/src/northbridge/intel/i945/gma.c ++++ b/src/northbridge/intel/i945/gma.c +@@ -26,6 +26,8 @@ + #include <string.h> + #include <pc80/vga.h> + #include <pc80/vga_io.h> ++#include <commonlib/helpers.h> ++ + + #include "i945.h" + #include "chip.h" +@@ -43,7 +45,7 @@ + #define PGETBL_CTL 0x2020 + #define PGETBL_ENABLED 0x00000001 + +-#define BASE_FREQUENCY 120000 ++#define BASE_FREQUENCY 100000 + + #if CONFIG_MAINBOARD_DO_NATIVE_VGA_INIT + +@@ -85,10 +87,10 @@ static int intel_gma_init(struct northbridge_intel_i945_config *conf, + u8 edid_data[128]; + unsigned long temp; + int hpolarity, vpolarity; +- u32 candp1, candn; +- u32 best_delta = 0xffffffff; ++ u32 smallest_err = 0xffffffff; + u32 target_frequency; + u32 pixel_p1 = 1; ++ u32 pixel_p2; + u32 pixel_n = 1; + u32 pixel_m1 = 1; + u32 pixel_m2 = 1; +@@ -158,43 +160,37 @@ static int intel_gma_init(struct northbridge_intel_i945_config *conf, + write32(pmmio + PORT_HOTPLUG_EN, conf->gpu_hotplug); + write32(pmmio + INSTPM, 0x08000000 | INSTPM_AGPBUSY_DIS); + +- target_frequency = mode->lvds_dual_channel ? mode->pixel_clock +- : (2 * mode->pixel_clock); +- +- /* Find suitable divisors. */ +- for (candp1 = 1; candp1 <= 8; candp1++) { +- for (candn = 5; candn <= 10; candn++) { +- u32 cur_frequency; +- u32 m; /* 77 - 131. */ +- u32 denom; /* 35 - 560. */ +- u32 current_delta; +- +- denom = candn * candp1 * 7; +- /* Doesnt overflow for up to +- 5000000 kHz = 5 GHz. */ +- m = (target_frequency * denom +- + BASE_FREQUENCY / 2) / BASE_FREQUENCY; +- +- if (m < 77 || m > 131) +- continue; +- +- cur_frequency = (BASE_FREQUENCY * m) / denom; +- if (target_frequency > cur_frequency) +- current_delta = target_frequency - cur_frequency; +- else +- current_delta = cur_frequency - target_frequency; +- +- if (best_delta > current_delta) { +- best_delta = current_delta; +- pixel_n = candn; +- pixel_p1 = candp1; +- pixel_m2 = ((m + 3) % 5) + 7; +- pixel_m1 = (m - pixel_m2) / 5; ++ pixel_p2 = mode->lvds_dual_channel ? 7 : 14; ++ target_frequency = mode->pixel_clock; ++ ++ /* Find suitable divisors, m1, m2, p1, n. */ ++ /* refclock * (5 * (m1 + 2) + (m1 + 2)) / (n + 2) / p1 / p2 */ ++ /* should be closest to target frequency as possible */ ++ u32 candn, candm1, candm2, candp1; ++ for (candm1 = 8; candm1 <= 18; candm1++) { ++ for (candm2 = 3; candm2 <= 7; candm2++) { ++ for (candn = 1; candn <= 6; candn++) { ++ for (candp1 = 1; candp1 <= 8; candp1++) { ++ u32 m = 5 * (candm1 + 2) + (candm2 + 2); ++ u32 p = candp1 * pixel_p2; ++ u32 vco = DIV_ROUND_CLOSEST(BASE_FREQUENCY * m, candn + 2); ++ u32 dot = DIV_ROUND_CLOSEST(vco, p); ++ u32 this_err = ABS(dot - target_frequency); ++ if ((m < 70) || (m > 120)) ++ continue; ++ if (this_err < smallest_err) { ++ smallest_err = this_err; ++ pixel_n = candn; ++ pixel_m1 = candm1; ++ pixel_m2 = candm2; ++ pixel_p1 = candp1; ++ } ++ } + } + } + } + +- if (best_delta == 0xffffffff) { ++ if (smallest_err == 0xffffffff) { + printk (BIOS_ERR, "Couldn't find GFX clock divisors\n"); + return -1; + } +@@ -216,8 +212,8 @@ static int intel_gma_init(struct northbridge_intel_i945_config *conf, + printk(BIOS_DEBUG, "Pixel N=%d, M1=%d, M2=%d, P1=%d\n", + pixel_n, pixel_m1, pixel_m2, pixel_p1); + printk(BIOS_DEBUG, "Pixel clock %d kHz\n", +- BASE_FREQUENCY * (5 * pixel_m1 + pixel_m2) / pixel_n +- / (pixel_p1 * 7)); ++ BASE_FREQUENCY * (5 * (pixel_m1 + 2) + (pixel_m2 + 2)) / ++ (pixel_n + 2) / (pixel_p1 * pixel_p2)); + + #if !IS_ENABLED(CONFIG_FRAMEBUFFER_KEEP_VESA_MODE) + write32(pmmio + PF_WIN_SZ(0), vactive | (hactive << 16)); +@@ -242,8 +238,8 @@ static int intel_gma_init(struct northbridge_intel_i945_config *conf, + write32(pmmio + PP_CONTROL, PANEL_UNLOCK_REGS + | (read32(pmmio + PP_CONTROL) & ~PANEL_UNLOCK_MASK)); + write32(pmmio + FP0(1), +- ((pixel_n - 2) << 16) +- | ((pixel_m1 - 2) << 8) | pixel_m2); ++ (pixel_n << 16) ++ | (pixel_m1 << 8) | pixel_m2); + write32(pmmio + DPLL(1), + DPLL_VGA_MODE_DIS | + DPLL_VCO_ENABLE | DPLLB_MODE_LVDS +@@ -252,8 +248,7 @@ static int intel_gma_init(struct northbridge_intel_i945_config *conf, + | (conf->gpu_lvds_use_spread_spectrum_clock + ? DPLL_INTEGRATED_CLOCK_VLV | DPLL_INTEGRATED_CRI_CLK_VLV + : 0) +- | (pixel_p1 << 16) +- | (pixel_p1)); ++ | (0x10000 << pixel_p1)); + mdelay(1); + write32(pmmio + DPLL(1), + DPLL_VGA_MODE_DIS | +@@ -261,8 +256,7 @@ static int intel_gma_init(struct northbridge_intel_i945_config *conf, + | (mode->lvds_dual_channel ? DPLLB_LVDS_P2_CLOCK_DIV_7 + : DPLLB_LVDS_P2_CLOCK_DIV_14) + | ((conf->gpu_lvds_use_spread_spectrum_clock ? 3 : 0) << 13) +- | (pixel_p1 << 16) +- | (pixel_p1)); ++ | (0x10000 << pixel_p1)); + mdelay(1); + write32(pmmio + HTOTAL(1), + ((hactive + right_border + hblank - 1) << 16) +-- +2.9.3 +