Testing of Tacoma has shown that the ASPEED master can be run at maximum
speed.
The exception is when wired externally with a cable, in which case we
use a divisor of two to ensure reliable operation.
Reviewed-by: Eddie James <eajames@xxxxxxxxxxxxx>
Signed-off-by: Joel Stanley <joel@xxxxxxxxx>
---
drivers/fsi/fsi-master-aspeed.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/drivers/fsi/fsi-master-aspeed.c b/drivers/fsi/fsi-master-aspeed.c
index c282de76e6e7..f503f64ab32b 100644
--- a/drivers/fsi/fsi-master-aspeed.c
+++ b/drivers/fsi/fsi-master-aspeed.c
@@ -83,7 +83,11 @@ static const u32 fsi_base = 0xa0000000;
#define FSI_LINK_ENABLE_SETUP_TIME 10 /* in mS */
-#define DEFAULT_DIVISOR 14
+/* Run the bus at maximum speed by default */
+#define FSI_DIVISOR_DEFAULT 1
+#define FSI_DIVISOR_CABLED 2
+static u16 aspeed_fsi_divisor = FSI_DIVISOR_DEFAULT;
+
#define OPB_POLL_TIMEOUT 10000
static int __opb_write(struct fsi_master_aspeed *aspeed, u32 addr,
@@ -385,9 +389,11 @@ static int aspeed_master_init(struct fsi_master_aspeed *aspeed)
opb_writel(aspeed, ctrl_base + FSI_MECTRL, reg);
reg = cpu_to_be32(FSI_MMODE_ECRC | FSI_MMODE_EPC | FSI_MMODE_RELA
- | fsi_mmode_crs0(DEFAULT_DIVISOR)
- | fsi_mmode_crs1(DEFAULT_DIVISOR)
+ | fsi_mmode_crs0(aspeed_fsi_divisor)
+ | fsi_mmode_crs1(aspeed_fsi_divisor)
| FSI_MMODE_P8_TO_LSB);
+ dev_info(aspeed->dev, "mmode set to %08x (divisor %d)\n",
+ be32_to_cpu(reg), aspeed_fsi_divisor);
opb_writel(aspeed, ctrl_base + FSI_MMODE, reg);
reg = cpu_to_be32(0xffff0000);
@@ -446,6 +452,11 @@ static int tacoma_cabled_fsi_fixup(struct device *dev)
/* If the routing GPIO is high we should set the mux to low. */
if (gpio) {
+ /*
+ * Cable signal integrity means we should run the bus
+ * slightly slower
+ */
+ aspeed_fsi_divisor = FSI_DIVISOR_CABLED;
gpiod_direction_output(mux_gpio, 0);
dev_info(dev, "FSI configured for external cable\n");
} else {
--
2.27.0
