ARM: mx7: psci: fix suspend/resume e10133 workaround

The e10133 workaround was broken in two places:

- The code intended to temporarily mask all interrupts in GPC_IMRx_CORE0.
  While the old register values were saved, the actual masking was
  missing.
- imx_udelay() expects the system counter to run at its base frequency,
  but the system counter is switched to a lower frequency earlier in
  psci_system_suspend(), leading to a much longer delay than intended.
  Replace the call with an equivalent loop (linux-imx 5.15 does the same)

This fixes the SoC hanging forever when there was already a wakeup IRQ
pending while suspending.

Fixes: 57b620255e ("imx: mx7: add system suspend/resume support")
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>

diff --git a/arch/arm/mach-imx/mx7/psci-mx7.c b/arch/arm/mach-imx/mx7/psci-mx7.c
index f32945e..699a256 100644 (file)
--- a/arch/arm/mach-imx/mx7/psci-mx7.c
+++ b/arch/arm/mach-imx/mx7/psci-mx7.c
@@ -643,8 +643,10 @@ __secure void psci_system_suspend(u32 __always_unused function_id,
        /* disable GIC distributor */
        writel(0, GIC400_ARB_BASE_ADDR + GIC_DIST_OFFSET);
 
-       for (i = 0; i < 4; i++)
+       for (i = 0; i < 4; i++) {
                gpc_mask[i] = readl(GPC_IPS_BASE_ADDR + GPC_IMR1_CORE0 + i * 4);
+               writel(~0, GPC_IPS_BASE_ADDR + GPC_IMR1_CORE0 + i * 4);
+       }
 
        /*
         * enable the RBC bypass counter here
@@ -668,7 +670,7 @@ __secure void psci_system_suspend(u32 __always_unused function_id,
                writel(gpc_mask[i], GPC_IPS_BASE_ADDR + GPC_IMR1_CORE0 + i * 4);
 
        /*
-        * now delay for a short while (3usec)
+        * now delay for a short while (~3usec)
         * ARM is at 1GHz at this point
         * so a short loop should be enough.
         * this delay is required to ensure that
@@ -677,7 +679,8 @@ __secure void psci_system_suspend(u32 __always_unused function_id,
         * or in case an interrupt arrives just
         * as ARM is about to assert DSM_request.
         */
-       imx_udelay(3);
+       for (i = 0; i < 2000; i++)
+               asm volatile("");
 
        /* save resume entry and sp in CPU0 GPR registers */
        asm volatile("mov %0, sp" : "=r" (val));