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fsi: aspeed: Run the bus at maximum speed

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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@linux.ibm.com>
Link: https://lore.kernel.org/r/20200728025527.174503-4-joel@jms.id.au
Signed-off-by: Joel Stanley <joel@jms.id.au>
This commit is contained in:
Joel Stanley 2020-07-28 12:25:25 +09:30
parent f369a29bdd
commit 4a80c2017b
1 changed files with 14 additions and 3 deletions
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17
drivers/fsi/fsi-master-aspeed.c
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@ -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 {