arm: mach-k3: am6_init: Prioritize MSMC traffic over DDR in NAVSS Northbridge

NB0 is bridge to SRAM and NB1 is bridge to DDR.

To ensure that SRAM transfers are not stalled due to delays during DDR
refreshes, SRAM traffic should be higher priority (threadmap=2) than
DDR traffic (threadmap=0).

This fixup is critical to provide deterministic access latency to
MSMC from ICSSG, it applies to all AM65 silicon revisions and is due
to incorrect reset values (has no erratum id) and statically setting
things up should be done independent of usecases and board.

This specific style of Northbridge configuration is specific only to
AM65x devices, follow-on K3 devices have different data prioritization
schemes (ASEL and the like) and hence the fixup applies purely to
AM65x.

Without this fix, ICSSG TX lock-ups due to delays in MSMC transfers in
case of SR1 devices, on SR2 devices, lockups were not observed so far
but high retry rates of ICSSG Ethernet (icssg-eth) and, thus, lower
throughput.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Acked-by: Andrew F. Davis <afd@ti.com>
Acked-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Benoit Parrot <bparrot@ti.com>
[Jan: rebased, dropped used define, extended commit log]
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
[Nishanth: Provide relevant context in the commit message]
Signed-off-by: Nishanth Menon<nm@ti.com>

diff --git a/arch/arm/mach-k3/am6_init.c b/arch/arm/mach-k3/am6_init.c
index 425b3f93c865b6addf7807b583d014a3762fd0ac..ffb7aaded2e731be97e2a906bbe6c04432d5df51 100644 (file)
--- a/arch/arm/mach-k3/am6_init.c
+++ b/arch/arm/mach-k3/am6_init.c
@@ -151,6 +151,19 @@ int fdtdec_board_setup(const void *fdt_blob)
        return fixup_usb_boot();
 }
 #endif
+
+static void setup_am654_navss_northbridge(void)
+{
+       /*
+        * NB0 is bridge to SRAM and NB1 is bridge to DDR.
+        * To ensure that SRAM transfers are not stalled due to
+        * delays during DDR refreshes, SRAM traffic should be higher
+        * priority (threadmap=2) than DDR traffic (threadmap=0).
+        */
+       writel(0x2, NAVSS0_NBSS_NB0_CFG_BASE + NAVSS_NBSS_THREADMAP);
+       writel(0x0, NAVSS0_NBSS_NB1_CFG_BASE + NAVSS_NBSS_THREADMAP);
+}
+
 void board_init_f(ulong dummy)
 {
 #if defined(CONFIG_K3_LOAD_SYSFW) || defined(CONFIG_K3_AM654_DDRSS)
@@ -168,6 +181,8 @@ void board_init_f(ulong dummy)
        /* Make all control module registers accessible */
        ctrl_mmr_unlock();
 
+       setup_am654_navss_northbridge();
+
 #ifdef CONFIG_CPU_V7R
        disable_linefill_optimization();
        setup_k3_mpu_regions();

diff --git a/arch/arm/mach-k3/include/mach/am6_hardware.h b/arch/arm/mach-k3/include/mach/am6_hardware.h
index 1908a13f0ff2d6bf1f2f0d36ace2617a85c7d65c..f533e22e061704b12887a36ba8ff341b887a0c3b 100644 (file)
--- a/arch/arm/mach-k3/include/mach/am6_hardware.h
+++ b/arch/arm/mach-k3/include/mach/am6_hardware.h
@@ -52,4 +52,10 @@
 /* MCU SCRATCHPAD usage */
 #define TI_SRAM_SCRATCH_BOARD_EEPROM_START CONFIG_SYS_K3_MCU_SCRATCHPAD_BASE
 
+/* NAVSS Northbridge config */
+#define        NAVSS0_NBSS_NB0_CFG_BASE                        0x03802000
+#define        NAVSS0_NBSS_NB1_CFG_BASE                        0x03803000
+
+#define        NAVSS_NBSS_THREADMAP                            0x10
+
 #endif /* __ASM_ARCH_AM6_HARDWARE_H */