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

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Date:   Mon, 13 Nov 2023 21:11:04 +0800
From:   Xiaolei Wang <xiaolei.wang@...driver.com>
To:     Frank.Li@....com, vkoul@...nel.org
Cc:     imx@...ts.linux.dev, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] dmaengine: fsl-edma: Do not suspend and resume the masked dma channel when the system is sleeping

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@...driver.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