[PATCH 1/2] dmaengine: fsl-edma: Do not suspend and resume the masked dma channel when the system is sleeping

[Xiaolei Wang <xiaolei.wang@windriver.com>]

Some channels may be masked. When the system is suspended,
if these masked channels are not filtered out, this will
lead to null pointer operations and system crash:

Unable to handle kernel NULL pointer dereference at virtual address
Mem abort info:
ESR = 0x0000000096000004
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x04: level 0 translation fault
Data abort info:
ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=0000000894300000
[00000000000002a0] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 989 Comm: sh Tainted: G B 6.6.0-16203-g557fb7a3ec4c-dirty #70
Hardware name: Freescale i.MX8QM MEK (DT)
pstate: 400000c5 (nZcv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  pc: fsl_edma_disable_request+0x3c/0x78
  lr: fsl_edma_disable_request+0x3c/0x78
  sp:ffff800089ae7690
  x29: ffff800089ae7690 x28: ffff000807ab5440 x27: ffff000807ab5830
  x26: 0000000000000008 x25: 0000000000000278 x24: 0000000000000001
  23: ffff000807ab4328 x22: 0000000000000000 x21: 0000000000000009
  x20: ffff800082616940 x19: 0000000000000000 x18: 0000000000000000
  x17: 3d3d3d3d3d3d3d3d x16: 3d3d3d3d3d3d3d3d x15: 3d3d3d3d3d3d3d3d
  x14: 3d3d3d3d3d3d3d3d x13: 3d3d3d3d3d3d3d3d x12: 1ffff00010d45724
  x11: ffff700010d45724 x10: dfff800000000000 x9: dfff800000000000
  x8: 00008fffef2ba8dc x7: 0000000000000001 x6: ffff800086a2b927
  x5: ffff800086a2b920 x4: ffff700010d45725 x3: ffff8000800d5bbc
  x2 : 0000000000000000 x1 : ffff000800c1d880 x0 : 0000000000000001
  Call trace:
   fsl_edma_disable_request+0x3c/0x78
   fsl_edma_suspend_late+0x128/0x12c
  dpm_run_callback+0xd4/0x304
   __device_suspend_late+0xd0/0x240
  dpm_suspend_late+0x174/0x59c
  suspend_devices_and_enter+0x194/0xd00
  pm_suspend+0x3c4/0x910

Fixes: 82d149b86d31 ("dmaengine: fsl-edma: add PM suspend/resume support")
Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
---
 drivers/dma/fsl-edma-main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/dma/fsl-edma-main.c b/drivers/dma/fsl-edma-main.c
index 4635e16d7705..52577fffc62b 100644
--- a/drivers/dma/fsl-edma-main.c
+++ b/drivers/dma/fsl-edma-main.c
@@ -631,6 +631,8 @@ static int fsl_edma_suspend_late(struct device *dev)
 
 	for (i = 0; i < fsl_edma->n_chans; i++) {
 		fsl_chan = &fsl_edma->chans[i];
+		if (fsl_edma->chan_masked & BIT(i))
+			continue;
 		spin_lock_irqsave(&fsl_chan->vchan.lock, flags);
 		/* Make sure chan is idle or will force disable. */
 		if (unlikely(!fsl_chan->idle)) {
@@ -655,6 +657,8 @@ static int fsl_edma_resume_early(struct device *dev)
 
 	for (i = 0; i < fsl_edma->n_chans; i++) {
 		fsl_chan = &fsl_edma->chans[i];
+		if (fsl_edma->chan_masked & BIT(i))
+			continue;
 		fsl_chan->pm_state = RUNNING;
 		edma_write_tcdreg(fsl_chan, 0, csr);
 		if (fsl_chan->slave_id != 0)
-- 
2.25.1