[PATCH 2/2] dmaengine: qcom: bam_dma: Do not touch remote BAM in remove()

[Mostafa Saleh <smostafa@google.com>]

Unbinding the crypto BAM through sysfs on X1P42100 resets the board.
bam_dma_remove() clears BAM_IRQ_SRCS_MSK_EE unconditionally. For a BAM
that is controlled or powered remotely the register may not be
accessible: the clock and power of the block belong to the remote side
or to the consumer of the BAM, which is why bam_init() already avoids
every register access for such a BAM when the DT provides num-channels
and qcom,num-ees.

The write is also unnecessary. On a remotely controlled BAM the driver
only ever sets per channel bits in the EE mask, in bam_chan_init_hw(),
and bam_free_chan() clears them again. Both run on behalf of a
consumer, which keeps the block clocked while they do.

Skip the write for both kinds of remotely managed BAM, using the same
condition as bam_init().

Fixes: 5172c9eb89d4 ("dmaengine: qcom: bam_dma: add controlled-remotely dt property")
Signed-off-by: Mostafa Saleh <smostafa@google.com>
---
 drivers/dma/qcom/bam_dma.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index bd583f78e0c1..d818fa1dba57 100644
--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -1407,8 +1407,15 @@ static void bam_dma_remove(struct platform_device *pdev)
 	dma_async_device_unregister(&bdev->common);
 
 	pm_runtime_get_sync(&pdev->dev);
-	/* mask all interrupts for this execution environment */
-	writel_relaxed(0, bam_addr(bdev, 0,  BAM_IRQ_SRCS_MSK_EE));
+
+	/*
+	 * Mask all interrupts for this execution environment. A remotely
+	 * controlled or powered BAM is left alone: it may be unclocked, and
+	 * the only bits this driver sets in its mask are the per channel
+	 * ones that bam_free_chan() cleared.
+	 */
+	if (!bdev->controlled_remotely && !bdev->powered_remotely)
+		writel_relaxed(0, bam_addr(bdev, 0,  BAM_IRQ_SRCS_MSK_EE));
 
 	free_irq(bdev->irq, bdev);
 
-- 
2.56.0.212.g129ede20d9-goog