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cci: Wait before reading status register 

The functions cci_enable_snoop_dvm_reqs and cci_disable_snoop_dvm_reqs write
in the SNOOP_CTRL_REGISTER of the slave interface and it polls the status
register to be sure that the operation is finished before leaving the
functions. If the write in SNOOP_CTRL_REGISTER is reordered after the first
read in the status register then these functions can finish before
enabling/disabling snoops and DVM messages.

The CCI500 TRM specifies:

	Wait for the completion of the write to the Snoop Control Register
	before testing the change_pending bit.

Change-Id: Idc7685963f412be1c16bcd3c6e3cca826e2fdf38
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>
This commit is contained in:
Roberto Vargas 2018-07-18 11:14:20 +01:00
parent f790cc0a9c
commit ae551a1370
1 changed files with 13 additions and 0 deletions
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13
drivers/arm/cci/cci.c
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@ -5,6 +5,7 @@
*/
#include <arch.h>
#include <arch_helpers.h>
#include <assert.h>
#include <cci.h>
#include <debug.h>
@ -142,6 +143,12 @@ void cci_enable_snoop_dvm_reqs(unsigned int master_id)
SLAVE_IFACE_OFFSET(slave_if_id) + SNOOP_CTRL_REG,
DVM_EN_BIT | SNOOP_EN_BIT);
/*
* Wait for the completion of the write to the Snoop Control Register
* before testing the change_pending bit
*/
dmbish();
/* Wait for the dust to settle down */
while (mmio_read_32(cci_base + STATUS_REG) & CHANGE_PENDING_BIT)
;
@ -163,6 +170,12 @@ void cci_disable_snoop_dvm_reqs(unsigned int master_id)
SLAVE_IFACE_OFFSET(slave_if_id) + SNOOP_CTRL_REG,
~(DVM_EN_BIT | SNOOP_EN_BIT));
/*
* Wait for the completion of the write to the Snoop Control Register
* before testing the change_pending bit
*/
dmbish();
/* Wait for the dust to settle down */
while (mmio_read_32(cci_base + STATUS_REG) & CHANGE_PENDING_BIT)
;