[coreboot-gerrit] [S] Change in coreboot[main]: arch/riscv/smp.c: Add comments and print messages

[Maximilian Brune (Code Review)]

Attention is currently required from: Philipp Hug.

Maximilian Brune has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/87300?usp=email )

Change subject: arch/riscv/smp.c: Add comments and print messages
......................................................................

arch/riscv/smp.c: Add comments and print messages

It should increase readability and make it easier to debug.

Signed-off-by: Maximilian Brune 
Change-Id: Ia9d77aa64482d5cd087a5b90c1fc80f8b3d6614c
---
M src/arch/riscv/smp.c
1 file changed, 10 insertions(+), 6 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/00/87300/1

diff --git a/src/arch/riscv/smp.c b/src/arch/riscv/smp.c
index a08e16b..2378e4e 100644
--- a/src/arch/riscv/smp.c
+++ b/src/arch/riscv/smp.c
@@ -27,6 +27,7 @@
 #define HART_SLEEPING 0x1
 #define HART_AWAKE    0x2

+// effectively only executed on harts that are not the working hart
 void smp_pause(int working_hartid)
 {
    int hartid = read_csr(mhartid);
@@ -37,6 +38,7 @@
    	set_msip(hartid, 0); // clear pending interrupts
    	write_csr(mie, MIP_MSIP); // enable only IPI (for smp_resume)
    	barrier();
+
    	atomic_set(&HLS()->entry.sync_a, HART_SLEEPING); // mark the hart as sleeping.

// pause hart
@@ -63,12 +65,13 @@
    }

int working_hartid = read_csr(mhartid);
+	printk(BIOS_DEBUG, "working_hartid: %d\n", working_hartid);

int hart_count = CONFIG_MAX_CPUS;
    if (CONFIG(RISCV_GET_HART_COUNT_AT_RUNTIME))
    	hart_count = smp_get_hart_count();

-	// check that all harts are present
+	// wake up all harts

u32 count_awake_harts = 0;
    for (int i = 0; i < hart_count; i++) {
@@ -96,21 +99,22 @@
    	}
    }

-	printk(BIOS_DEBUG, "waiting for all harts to wake up...\n");
-	// confirm that all harts are wake
+	printk(BIOS_SPEW, "waiting for all harts to wake up...\n");
+
    for (int i = 0; i < hart_count; i++) {
    	// The working hart never sleeps. It is a hard working hart.
    	if (i == working_hartid || !OTHER_HLS(i)->enabled)
    		continue;

-		// wait for hart to publish its waking state
+		printk(BIOS_SPEW, "waiting for hart %d\n", i);
    	while (atomic_read(&OTHER_HLS(i)->entry.sync_a) != HART_AWAKE)
-			;
+			; //TODO add timeout
+
    	// signal to hart that we noticed it woke up
    	atomic_set(&HLS()->entry.sync_b, HART_AWAKE);
    	count_awake_harts++;
    }
-	printk(BIOS_DEBUG, "all harts up and running...\n");
+	printk(BIOS_DEBUG, "all harts are up and running\n");

if ((hart_count - 1) != count_awake_harts) { // exclude working hart
    	/*