Commit 4a80c201 authored by Joel Stanley's avatar Joel Stanley
Browse files

fsi: aspeed: Run the bus at maximum speed 



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: default avatarEddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20200728025527.174503-4-joel@jms.id.au


Signed-off-by: default avatarJoel Stanley <joel@jms.id.au>
parent f369a29b

drivers/fsi/fsi-master-aspeed.c

+14 −3
Original line number Diff line number Diff line
@@ -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 {

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