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* [PATCH v4] dmaengine: qcom: bam_dma: Avoid writing unavailable register
@ 2024-12-20  9:42 Md Sadre Alam
  2024-12-24 10:41 ` Vinod Koul
                   ` (2 more replies)
  0 siblings, 3 replies; 12+ messages in thread
From: Md Sadre Alam @ 2024-12-20  9:42 UTC (permalink / raw)
  To: vkoul, robin.murphy, u.kleine-koenig, martin.petersen, fenghua.yu,
	av2082000, linux-arm-msm, dmaengine, linux-kernel
  Cc: quic_mmanikan, quic_srichara, quic_varada, quic_mdalam

Avoid writing unavailable register in BAM-Lite mode.
BAM_DESC_CNT_TRSHLD register is unavailable in BAM-Lite
mode. Its only available in BAM-NDP mode. So only write
this register for clients who is using BAM-NDP.

Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
---
Change in [v4]

* Added in_range() macro

Change in [v3]

* Removed BAM_LITE macro

* Updated commit message

* Adjusted if condition check

* Renamed BAM-NDP macro to BAM_NDP_REVISION_START and
   BAM_NDP_REVISION_END

Change in [v2]

* Replace 0xff with REVISION_MASK in the statement
   bdev->bam_revision = val & REVISION_MASK

Change in [v1]

* Added initial patch

 drivers/dma/qcom/bam_dma.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index bbc3276992bb..c14557efd577 100644
--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -59,6 +59,9 @@ struct bam_desc_hw {
 #define DESC_FLAG_NWD BIT(12)
 #define DESC_FLAG_CMD BIT(11)
 
+#define BAM_NDP_REVISION_START	0x20
+#define BAM_NDP_REVISION_END	0x27
+
 struct bam_async_desc {
 	struct virt_dma_desc vd;
 
@@ -398,6 +401,7 @@ struct bam_device {
 
 	/* dma start transaction tasklet */
 	struct tasklet_struct task;
+	u32 bam_revision;
 };
 
 /**
@@ -441,8 +445,10 @@ static void bam_reset(struct bam_device *bdev)
 	writel_relaxed(val, bam_addr(bdev, 0, BAM_CTRL));
 
 	/* set descriptor threshold, start with 4 bytes */
-	writel_relaxed(DEFAULT_CNT_THRSHLD,
-			bam_addr(bdev, 0, BAM_DESC_CNT_TRSHLD));
+	if (in_range(bdev->bam_revision, BAM_NDP_REVISION_START,
+		     BAM_NDP_REVISION_END))
+		writel_relaxed(DEFAULT_CNT_THRSHLD,
+			       bam_addr(bdev, 0, BAM_DESC_CNT_TRSHLD));
 
 	/* Enable default set of h/w workarounds, ie all except BAM_FULL_PIPE */
 	writel_relaxed(BAM_CNFG_BITS_DEFAULT, bam_addr(bdev, 0, BAM_CNFG_BITS));
@@ -1000,9 +1006,10 @@ static void bam_apply_new_config(struct bam_chan *bchan,
 			maxburst = bchan->slave.src_maxburst;
 		else
 			maxburst = bchan->slave.dst_maxburst;
-
-		writel_relaxed(maxburst,
-			       bam_addr(bdev, 0, BAM_DESC_CNT_TRSHLD));
+		if (in_range(bdev->bam_revision, BAM_NDP_REVISION_START,
+			     BAM_NDP_REVISION_END))
+			writel_relaxed(maxburst,
+				       bam_addr(bdev, 0, BAM_DESC_CNT_TRSHLD));
 	}
 
 	bchan->reconfigure = 0;
@@ -1192,10 +1199,11 @@ static int bam_init(struct bam_device *bdev)
 	u32 val;
 
 	/* read revision and configuration information */
-	if (!bdev->num_ees) {
-		val = readl_relaxed(bam_addr(bdev, 0, BAM_REVISION));
+	val = readl_relaxed(bam_addr(bdev, 0, BAM_REVISION));
+	if (!bdev->num_ees)
 		bdev->num_ees = (val >> NUM_EES_SHIFT) & NUM_EES_MASK;
-	}
+
+	bdev->bam_revision = val & REVISION_MASK;
 
 	/* check that configured EE is within range */
 	if (bdev->ee >= bdev->num_ees)
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2025-01-10 12:23 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-12-20  9:42 [PATCH v4] dmaengine: qcom: bam_dma: Avoid writing unavailable register Md Sadre Alam
2024-12-24 10:41 ` Vinod Koul
2025-01-07 21:30 ` Georgi Djakov
2025-01-08 11:10   ` Vinod Koul
2025-01-08 11:14     ` Md Sadre Alam
2025-01-10  5:23     ` Md Sadre Alam
2025-01-08 11:14   ` Md Sadre Alam
2025-01-10  5:21   ` Md Sadre Alam
2025-01-10 10:29 ` Stephan Gerhold
2025-01-10 11:59   ` Md Sadre Alam
2025-01-10 12:07     ` Stephan Gerhold
2025-01-10 12:23       ` Md Sadre Alam

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