Re: [PATCH] dmaengine: qcom: bam_dma: Avoid writing unavailable register

Md Sadre Alam <quic_mdalam@xxxxxxxxxxx> · Tue, 26 Nov 2024 10:27:13 +0530

On 11/23/2024 10:06 AM, Varadarajan Narayanan wrote:
On Fri, Nov 22, 2024 at 12:46:49PM +0530, Md Sadre Alam wrote:
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 avoid writing
this register for clients who is using BAM-Lite mode.

Signed-off-by: Md Sadre Alam <quic_mdalam@xxxxxxxxxxx>
---
  drivers/dma/qcom/bam_dma.c | 22 ++++++++++++++--------
  1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index d43a881e43b9..13a08c03746b 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_LITE	0x13
+#define BAM_NDP		0x20
+
  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 +445,9 @@ 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 (bdev->bam_revision >= BAM_LITE && bdev->bam_revision < BAM_NDP)
+		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 +1005,9 @@ 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 (bdev->bam_revision >= BAM_LITE && bdev->bam_revision < BAM_NDP)
+			writel_relaxed(maxburst,
+				       bam_addr(bdev, 0, BAM_DESC_CNT_TRSHLD));
  	}

  	bchan->reconfigure = 0;
@@ -1192,10 +1197,11 @@ 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 & 0xff;

Use REVISION_MASK instead of 0xff
Ok

-Varada

  	/* check that configured EE is within range */
  	if (bdev->ee >= bdev->num_ees)
--
2.34.1








