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-rw-r--r--resources/libreboot/patch/coreboot/2a3434757ef425dbdfedf1fc69e1a033a6e7310d/grub/t60/0003-i945-gma.c-use-latest-linux-code-to-calculate-diviso.patch174
1 files 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
new file mode 100644
index 00000000..86bd6cb0
--- /dev/null
+++ 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
+
generated by cgit v1.2.3-70-g09d2 (git 2.47.0) at 2024-11-22 07:26:19 +0000