lib: Remove redundant sbi_platform_ipi_clear() calls

The sbi_platform_ipi_clear() called from wait_for_coldboot() and sbi_hsm_hart_wait() is redundant because IPI will be automatically cleared by sbi_platform_ipi_init() called from sbi_ipi_init(). Further, wait_for_coldboot() is common for warm startup and warm resume path so the sbi_platform_ipi_clear() called in warm resume path cause resuming HART to miss an IPI injected other HART to wakeup the HART. Signed-off-by: Anup Patel <[email protected]> Reviewed-by: Atish Patra <[email protected]>
pxk27 · Mar 3, 2021 · 50d4fde · 50d4fde
1 parent b9cf617
commit 50d4fde
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Showing 3 changed files with 16 additions and 7 deletions.
diff --git a/lib/sbi/sbi_hsm.c b/lib/sbi/sbi_hsm.c
@@ -107,7 +107,6 @@ void sbi_hsm_prepare_next_jump(struct sbi_scratch *scratch, u32 hartid)
 static void sbi_hsm_hart_wait(struct sbi_scratch *scratch, u32 hartid)
 {
 	unsigned long saved_mie;
-	const struct sbi_platform *plat = sbi_platform_ptr(scratch);
 	struct sbi_hsm_data *hdata = sbi_scratch_offset_ptr(scratch,
 							    hart_data_offset);
 	/* Save MIE CSR */
@@ -124,8 +123,10 @@ static void sbi_hsm_hart_wait(struct sbi_scratch *scratch, u32 hartid)
 	/* Restore MIE CSR */
 	csr_write(CSR_MIE, saved_mie);
 
-	/* Clear current HART IPI */
-	sbi_platform_ipi_clear(plat, hartid);
+	/*
+	 * No need to clear IPI here because the sbi_ipi_init() will
+	 * clear it for current HART via sbi_platform_ipi_init().
+	 */
 }
 
 int sbi_hsm_init(struct sbi_scratch *scratch, u32 hartid, bool cold_boot)

diff --git a/lib/sbi/sbi_init.c b/lib/sbi/sbi_init.c
@@ -130,7 +130,6 @@ static unsigned long coldboot_done;
 static void wait_for_coldboot(struct sbi_scratch *scratch, u32 hartid)
 {
 	unsigned long saved_mie, cmip;
-	const struct sbi_platform *plat = sbi_platform_ptr(scratch);
 
 	/* Save MIE CSR */
 	saved_mie = csr_read(CSR_MIE);
@@ -167,8 +166,14 @@ static void wait_for_coldboot(struct sbi_scratch *scratch, u32 hartid)
 	/* Restore MIE CSR */
 	csr_write(CSR_MIE, saved_mie);
 
-	/* Clear current HART IPI */
-	sbi_platform_ipi_clear(plat, hartid);
+	/*
+	 * The wait for coldboot is common for both warm startup and
+	 * warm resume path so clearing IPI here would result in losing
+	 * an IPI in warm resume path.
+	 *
+	 * Also, the sbi_platform_ipi_init() called from sbi_ipi_init()
+	 * will automatically clear IPI for current HART.
+	 */
 }
 
 static void wake_coldboot_harts(struct sbi_scratch *scratch, u32 hartid)

diff --git a/lib/sbi/sbi_ipi.c b/lib/sbi/sbi_ipi.c
@@ -230,7 +230,10 @@ int sbi_ipi_init(struct sbi_scratch *scratch, bool cold_boot)
 	ipi_data = sbi_scratch_offset_ptr(scratch, ipi_data_off);
 	ipi_data->ipi_type = 0x00;
 
-	/* Platform init */
+	/*
+	 * Initialize platform IPI support. This will also clear any
+	 * pending IPIs for current/calling HART.
+	 */
 	ret = sbi_platform_ipi_init(sbi_platform_ptr(scratch), cold_boot);
 	if (ret)
 		return ret;