drivers/analogix/anx7625: prevent video clock jitter on IVO panels
The MIPI source video data has a large variation (e.g. 59Hz ~ 61Hz),
anx7625 defines K ratio for matching MIPI input video clock and
DP output video clock. A bigger k value can match a bigger video data
variation. IVO panel has smaller variation than DP CTS spec, so decrease
k value to 0x3b.
BUG=b:194659777
BRANCH=none
TEST=Display is normal on Asurada
Change-Id: If3a09811999babda45e9a9a559dd447920109204
Signed-off-by: Xin Ji <xji@analogixsemi.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57439
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
diff --git a/src/drivers/analogix/anx7625/anx7625.c b/src/drivers/analogix/anx7625/anx7625.c
index e37e047..11e9ed1 100644
--- a/src/drivers/analogix/anx7625/anx7625.c
+++ b/src/drivers/analogix/anx7625/anx7625.c
@@ -381,7 +381,7 @@
ret |= anx7625_reg_write(bus, RX_P1_ADDR, MIPI_PLL_N_NUM_7_0,
(n & 0xff));
/* diff */
- ret |= anx7625_reg_write(bus, RX_P1_ADDR, MIPI_DIGITAL_ADJ_1, 0x3d);
+ ret |= anx7625_reg_write(bus, RX_P1_ADDR, MIPI_DIGITAL_ADJ_1, dt->k_val);
ret |= anx7625_odfc_config(bus, post_divider - 1);
@@ -804,6 +804,20 @@
dt->vback_porch = (edid->mode.vbl - edid->mode.vso -
edid->mode.vspw - edid->mode.vborder);
+ /*
+ * The k_val is a ratio to match MIPI input and DP output video clocks.
+ * Most panels can follow the default value (0x3d).
+ * IVO panels have smaller variation than DP CTS spec and need smaller
+ * k_val (0x3b).
+ */
+ if (!strncmp(edid->manufacturer_name, "IVO", 3)) {
+ dt->k_val = 0x3b;
+ ANXINFO("detected IVO panel, use k value 0x3b\n");
+ } else {
+ dt->k_val = 0x3d;
+ ANXINFO("set default k value to 0x3d for panel\n");
+ }
+
ANXINFO("pixelclock(%d).\n"
" hactive(%d), hsync(%d), hfp(%d), hbp(%d)\n"
" vactive(%d), vsync(%d), vfp(%d), vbp(%d)\n",
diff --git a/src/drivers/analogix/anx7625/anx7625.h b/src/drivers/analogix/anx7625/anx7625.h
index c0b33b2..bba42cb 100644
--- a/src/drivers/analogix/anx7625/anx7625.h
+++ b/src/drivers/analogix/anx7625/anx7625.h
@@ -350,6 +350,7 @@
unsigned int vfront_porch;
unsigned int vback_porch;
unsigned int vsync_len;
+ unsigned int k_val;
};
int anx7625_dp_start(uint8_t bus, const struct edid *edid);